(2024) 22:348
Bick et al. BMC Medicine
https://doi.org/10.1186/s12916-024-03558-x

BMC Medicine

RESEARCH

Open Access

Impact of a school‑based water and hygieneintervention on child health and school
attendance in Addis Ababa, Ethiopia:
a cluster‑randomised controlled trial
Sarah Bick1, Alem Ezezew2, Charles Opondo3, Baptiste Leurent4, Wossen Argaw5, Erin C. Hunter6,7,8,
Oliver Cumming1, Elizabeth Allen3 and Robert Dreibelbis1*
Abstract
Background School-based water, sanitation and hygiene (WASH) may improve the health and attendance of schoolchildren, particularly post-menarcheal girls, but existing evidence is mixed. We examined the impact of an urban
school-based WASH programme (Project WISE) on child health and attendance.
Methods The WISE cluster-randomised trial, conducted in 60 public primary schools in Addis Ababa, Ethiopia
over one academic year, enrolled 2–4 randomly selected classes per school (~ 100 pupils) from grades 2 to 8 (aged
7–16) in an ‘open cohort’. Schools were assigned 1:1 by stratified randomisation to receive the intervention during the 2021/2022 or the 2022/2023 academic year (waitlist control). The intervention included improvements
to drinking water storage, filtration and access, handwashing stations and behaviour change promotion. Planned
sanitation improvements were not realised. At four unannounced classroom visits post-intervention (March–June2022), enumerators recorded primary outcomes of roll-call absence, and pupil-reported respiratory illness and diarrhoea in the past 7 days among pupils present. Analysis was by intention-to-treat.
Results Of 83 eligible schools, 60 were randomly selected and assigned. In total, 6229 eligible pupils were enrolled(median per school 101.5; IQR 94–112), 5987 enrolled at study initiation (23rd November–22nd December 2021)
and the remaining 242 during follow-up. Data were available on roll-call absence for 6166 pupils (99.0%), and pupilreported illness for 6145 pupils (98.6%). We observed a 16% relative reduction in odds of pupil-reported respiratory
illness in the past 7 days during follow-up in intervention vs. control schools (aOR 0.84; 95% CI 0.71–1.00; p = 0.046).
There was no evidence of effect on pupil-reported diarrhoea in the past 7 days (aOR 1.15; 95% CI 0.84–1.59; p = 0.39)
nor roll-call absence (aOR 1.07; 95% 0.83–1.38; p = 0.59). There was a small increase in menstrual care self-efficacy(aMD 3.32 on 0–100 scale; 95% CI 0.05–6.59), and no evidence of effects on other secondary outcomes.
Conclusions This large-scale intervention to improve school WASH conditions city-wide had a borderline impact
on pupil-reported respiratory illness but no effect on diarrhoeal disease nor pupil absence. Future research should
establish relationships between WASH-related illness, absence and other educational outcomes.
Trial registration ClinicalTrials.gov, number NCT05024890.
Keywords School health, Hand hygiene, Water, Respiratory illness, Diarrhoea, School absence, Ethiopia*Correspondence:
Robert Dreibelbis
robert.dreibelbis@lshtm.ac.uk
Full list of author information is available at the end of the article© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which
permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to theoriginal author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images orother third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line
to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory
regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of thislicence, visit http://creativecommons.org/licenses/by/4.0/.

Bick et al. BMC Medicine(2024) 22:348

Background
School-aged children in low- and middle-income countries (LMICs) are particularly susceptible to water, sanitation and hygiene (WASH)-related morbidities including
gastrointestinal [1] and respiratory infections [2], often
due to frequent social mixing [3]. In low-resource settings, these health risks are particularly associated with
absence from school, lower test scores and dropout [4,5], with implications on downstream social, occupationaland health outcomes [6]. WASH interventions in schools
are often expected to have gendered impacts: while reasons for absence and dropout are varied [5], inadequate
WASH conditions in schools may present barriers toattendance, including through lack of hygienic menstrualmaterials, disposal facilities and privacy leaving girls
with limited options for menstrual hygiene management(MHM), and impacting educational progression [7].
Pupils’ academic performance may also be affected bydehydration where there is inadequate water supply [8].
Although WASH in schools interventions have been
hypothesised to improve children’s health and attendanceoutcomes, evidence of their impact has been mixed. A
systematic review of varied WASH in schools intervention studies in low-income countries, including provisionof water for drinking and handwashing, water quality,
sanitation, and hygiene promotion [9], found significant
reductions in pupil-reported diarrhoeal disease between
29 and 50%, and reduced incidence of respiratory illness.
Other studies, however, found no significant impacts or
saw positive impacts for only select disease outcomes[10, 11]. Mixed health effects are observed in other randomised trials in urban settings [12–14]. Impact on
absence is similarly ambiguous: WASH improvements
have been shown to reduce absence [9, 15], but only one[10] randomised controlled trial reports significantly
lower overall absence rates. Some studies observed specific impacts on girls’ absence alone [16], or on absence
due to diarrhoea [17].
Access to safe WASH facilities in school environments is included under Sustainable Development Goal
(SDG) 6 [18] as essential in ensuring dignity and equity,and promoting women’s equality and empowerment. To
achieve access to safe WASH, interventions must ensuresustained management of water and sanitation services over time [11], including consistent availability ofsoap and water for practising handwashing [19]. Several
publications highlight that combined WASH interventions versus single interventions—such as handwashingalone—may be necessary to transform school environments to the extent that the risk of illness and absence isreduced [9]. However, there is limited robust evidence forthe effectiveness of combined interventions delivered atscale in urban settings.

Page 2 of 12

The aim of this trial was to evaluate the effectivenessof a large-scale urban WASH in schools intervention,
including water and sanitation infrastructure, behaviour change promotion and targeted MHM services,in schools in Addis Ababa, Ethiopia. ‘Project WISE(WASH in Schools for Everyone)’, implemented by USbased NGO Splash in Addis Ababa public schools, isbeing delivered to pre-defined groups of schools on anannual basis. We hypothesised that the intervention
would improve child health and school attendance, withgreater impacts among post-menarcheal girls, and usedunannounced attendance checks to avoid bias commonly
associated with absence measurement [20].

Methods
Study design

The WISE evaluation was a parallel two-arm schoolbased cluster-randomised controlled trial, with 60
public primary schools in Addis Ababa, Ethiopia constituting the study clusters. We used a cluster-randomised
design because the intervention evaluated was deliveredat the school level and comprised changes to the whole
school environment. Seventeen additional kindergarten
schools were enrolled as part of a sub-study estimating
the impact of Project WISE on kindergarten pupils, to bereported in a separate publication.
The trial was conducted over the course of one Ethiopian academic year (November 2021 to July 2022; schools
were open from September to July) and followed an ‘open
cohort’ design to minimise participant attrition. Between
two and four sentinel classrooms of pupils were randomly selected for follow-up during the year, with pupils
who joined the class late, left the class, or were absent
from the first visit contributing data to analysis. Followup consisted of four unannounced visits to sentinel classrooms post-intervention (approximately every 4 weeks),
concurrently in intervention and control arms.
Participants

The study population comprised primary school pupils
aged 7–16 years attending schools due to receive the
WISE intervention in either the 2021/2022 or 2022/2023
academic years. In order to have sufficient pupils in theeligible age range, we excluded schools without pupils
in grades 2–8. We also excluded schools that received a
WASH intervention in the 3 years prior to study activities
and schools that provided education to vulnerable populations only. Sixty schools meeting these criteria wererandomly selected for participation.
Within each participating school, between two andfour classes were selected from grades 2–8. We obtained
enrolment data (number of pupils and classes) for allBick et al. BMC Medicine(2024) 22:348

grades in the school and estimated mean class size foreach grade. In order to have sufficient older pupils forage-specific secondary outcome measures, we followed astratified selection process, selecting one class each from
grades 2–5 and grades 6–8, then continued alternatingfrom younger grades and older grades until there were
estimated > 100 pupils.
All eligible schools had consented to the receipt of the
Project WISE intervention. Once the random allocation
had been determined, formal consent for participation in
the trial was sought from school principals in loco parentis, on behalf of all pupils in the school. School principals received guidance for communicating to parents,
and parental information sheets and opt-out forms were
distributed to all pupils in the sentinel classes at least
1 week before pupil enrolment; additional information
sheets were provided in case of unexpected variation inclass sizes and enrolment of additional pupils throughout the year. Pupils were excluded from data collection if
their parent or guardian returned the opt-out form at any
point and were required to give oral assent before eachdata collection activity.
Pupils were included in data collection regardless ofage in order to minimise risk of social exclusion in theclassroom if particular pupils were excluded, but only
pupils aged 7–16 at enrolment were included in the analysis. Some data collection activities were restricted tosubgroups of pupils by age and gender.
Randomisation and masking

Randomisation was conducted in July 2021, using a random number generator in Stata version 17.0 (StataCorp,
College Station, TX, USA). From the list of 143 schools
due to receive the intervention, we excluded ineligible
schools (as described above), and then randomly selected
60 schools of 83 eligible schools for participation. Randomisation was stratified by school size (< or ≥ 1200
pupils) and presence of a kindergarten (to facilitate thekindergarten sub-study). Within strata, the schools
were randomly ranked, and the first half of the schools
assigned to the intervention (implementation during
the 2021/2022 academic year). The remaining schools
were assigned to the waitlist control arm, to receive theintervention in the 2022/2023 academic year, after study
completion. Investigators performing the randomisation had no prior knowledge of any of the study schools.
Due to the visible, prominent nature of the intervention,masking of school administrators, participants, or thosedelivering the intervention was not possible. Outcome
assessors were not informed of treatment assignment,
but might have inferred it, for example, from the distinctive WASH infrastructure components.

Page 3 of 12

Intervention components

The Project WISE intervention combined infrastructure and behaviour change promotion activities, so that
handwashing and drinking exclusively from filtered water
become normative behaviours, and girls are able to manage menses at school. Intervention design was informedby the behaviour-centred design approach [21] to alter
behaviour through environmental cues, along with activity-based curricula, and pupil and teacher motivators.
The intervention was delivered at the school level, so all
children attending school were exposed to the intervention regardless of trial participation.
Infrastructure components included correcting water
storage capacity deficits through water storage tanks;
water filtration systems for drinking water; and durable
plastic drinking water and handwashing stations withspecific features differentiating their use and installedwith taps to meet sufficient tap-to-pupil ratios. Further
details and images (Figs. S1–S5) are provided in Additional File 1. The intervention also includes the provisionof new or rehabilitated toilet facilities to meet standards;
however, this component is managed by the Addis Ababa
Education Bureau on a separate timeline and was notdelivered to intervention schools until after the evaluation period.
Splash staff conducted a site engagement meeting with school administration and worked with theschool to organise a family ‘soap drive’ and ‘menstrual
pad drive’ during school registration, whereby familiesof pupils are encouraged to donate hygiene products tothe school to ensure availability of products throughout
the year. Two ‘focal teachers’ per school were trained topromote the WASH programme and organise a 20 to
30-pupil ‘hygiene club’ at each school. The 1-day training
for hygiene focal teachers covered safe water and water
conservation, handwashing, personal hygiene, sanitation,and hygiene clubs and action planning. Two additional
female focal teachers and one male focal teacher weretrained to organise a ‘gender club’ focussed on MHM,
which took place over 2 days with 20–30 girls and 20–30
boys trained on MHM. The gender club focal teachers
were trained in puberty, menstrual health and discussing
sensitive topics. Focal teachers then organised a parentteacher association orientation and delivered information
on MHM to parents. School janitors, maintenance staff,
and food handlers also received training on hygiene andoperation and maintenance of infrastructure.
Splash staff also supported focal teachers in training thehygiene club members to influence their peers throughmonitoring handwashing during breaks, ensuring soap
availability at handwashing stations, delivering hygiene
messaging during school announcements, and assistingBick et al. BMC Medicine(2024) 22:348

in planning event days promoting hygiene school-wide.
Members held monthly meetings to track progress andbring issues and requests to school leadership. Within the
menstrual health programme, all children aged 10 years
and older received an education session on puberty
and menstruation, including a Q&A session and product demonstration for girls, and a puberty workshop forboys. Peer mentoring of younger girls by older girls took
place over four sessions. Menstrual health event days
were also organised.
Interventions included behavioural ‘nudges’ [22] to
subtly guide pupils towards the intended behaviours,
such as mirrors and posters at handwashing stations, andbrightly coloured vests for hygiene club members to wear
during handwashing monitoring.
School engagement and training began in November
2021, and all infrastructure components were installed(excluding sanitation infrastructure) and core training
modules delivered by January 2022 in all 30 intervention schools. School and pupil enrolment activities took
place concurrent with intervention delivery (November to December 2021); therefore, outcomes assessedat enrolment were not included in the primary impact
assessment.
Data collection

Between May and July 2021, data collection tools andmethods for school and pupil enrolment and routine
follow-up surveys were piloted in five randomly selectedschools not included in the primary impact evaluation
where Splash implemented the WISE intervention in2020 / 2021. During piloting, in-country data collection
partners followed full study procedures outlined below,
with one minor variation: follow-up of sentinel classrooms occurred 3 weeks after enrolment and only one
round of follow-up occurred. The study pilot was used toassess the logistics of field data collection, verify assumptions made in sample size calculations, and test and adapt
MHM scales. Minor adjustments to class selection procedures were made as a result.
Data collection activities were completed in 1 day perschool. Following school enrolment and selection of sentinel classes, a team of trained enumerators visited theclassrooms and conducted a detailed enrolment survey
using tablets, one-to-one with assenting pupils (approximately 15 min), including demographic informationand household WASH access, self-reported number offull- and partial-days absent in the past week, causes ofabsence, and symptoms of infectious disease over thepreceding 2 and 7 days. These surveys were used to create a digital roster of pupils in sentinel classes, which was
automatically updated as new pupils were enrolled or left
the class during the academic year. A pupil identification

Page 4 of 12

number was assigned internally to all pupils on the roster
to anonymously link their data across surveys.
Between March and June 2022, enumerators conductedfour unannounced follow-up visits to sentinel classes ineach school. At the first three follow-ups, enumerators
took attendance using the digital rosters and conducteda brief survey with each pupil present (< 5 min) collecting data only on self-reported absence, causes of absence,
diarrhoea and respiratory illness in the past week. Pupils
absent from the initial enrolment survey completed theenrolment survey at the first follow-up visit they were
present for, and were retrospectively marked as absent
from all previous visits conducted while they had beenenrolled at the school. If a pupil was absent from twoconsecutive follow-ups, enumerators were automatically
prompted to ask teachers if the pupil had dropped out ofschool, and, if they had, to note the date of dropout andreason for dropout if known.
At the final follow-up, attendance was taken and all
outcomes were assessed, including wellbeing and menstrual health outcomes. Pupils meeting inclusion criteria for the Strengths and Difficulties Questionnaire [23](aged 11 and above), and the menstrual health measures(post-menarcheal girls aged ten and above) were identified and given their pupil identification number to link
their records with these self-completed paper-basedquestionnaires.
Age or date of birth (if known) and gender were selfreported by pupils at enrolment. At the final follow-up,
age and date of birth were double-checked to ensure
accuracy and updated. Age at enrolment was calculated
based on the updated records.
Outcomes

All outcomes were measured at the individual participant
level. The primary health outcomes were pupil-reported
diarrhoea (defined as the occurrence of at least threeloose stools in a 24-h period) and pupil-reported respiratory illness (defined as the occurrence of cough, sneezingor rhinorrhoea) in the past 7 days. Both were recorded
at each follow-up visit as dichotomous variables. The primary absence outcome was roll-call absence, recorded ateach follow-up as a dichotomous variable.
Secondary outcomes were pupil-reported absence(number of full days reported absent out of number ofdays of reporting in the past week); pupil-reported diarrhoea and pupil-reported respiratory illness in the past
2 days; Strengths and Difficulties Questionnaire (SDQ25) [23] total difficulties score, a widely used measure ofpupil behavioural and mental health challenges designed
for use among school-aged children that has been used
in a number of Sub-Saharan African countries [24],measured among children aged 11–16 at final follow-up;

Bick et al. BMC Medicine(2024) 22:348

Self-efficacy in Addressing Menstrual Needs Scale(SAMNS-26) [25] total score, a measure of girls’ confidence in addressing their menstrual needs; and Menstrual Practice Needs Scale (MPNS-36) [26] total score,a measure of how well current menstrual practices areperceived to meet the girls’ needs, with SAMNS-26 andMPNS-36 both measured among post-menarcheal girls
aged 10–16 at final follow-up.
Other outcomes were absence due to illness, diarrhoea,
and respiratory illness; 7- and 2-day occurrence of earache (negative control for illness outcomes, as earache is
not feasibly affected by the intervention); child subjective
wellbeing assessed through a smiley faces visual analogue(1–5 scale, with 5 being the best mood possible and 1
the worst); Sanitation-related Quality of Life (SanQoL-5)
applying attribute weights from a study in Ethiopia [preprint] [27]; change in gender parity in school enrolment
over the academic year using the adjusted gender parity
index [28]; and SAMNS-26 and MPNS-36 sub-scales.
Statistical analysis

Sample size calculations were based on estimating themean difference between arms in pupil-level proportionsof illness or absence across the follow-ups. Assuming themean pupil-level proportions of follow-ups reporting
diarrhoea in the control group was 0.08 (SD 0.05), a twosided type I error (α) of 0.05, and intracluster correlation
coefficient (ICC) of 0.15 (conservatively; ICC estimatesfor pupil-reported illness outcomes in our pilot study
ranged from 0.07–0.10), we estimated 50 schools (25per arm) with 100 children per school was sufficient todetect a reduction in the mean proportion of follow-ups
with diarrhoea of 0.016 (standardised effect size 0.32).
This standardised effect size equates to a reduction in
the mean proportion of follow-ups reporting respiratory
infection of 0.084 and a reduction of 0.022 in the mean
proportion of follow-ups absent as assessed through rollcall at each follow-up, based on SD estimates from pilot
data. Schools were oversampled to account for cluster
attrition; we randomised 60 schools to meet the sample
size of 50 schools with 17% attrition.
The statistical analysis plan was pre-registered on 1st
March 2023 [29] before allocation was revealed. Analyses
were done by intention-to-treat. Characteristics of thechildren and schools at enrolment were summarised by
the treatment arm. Statistical analyses of the outcomes
were conducted at the individual level with mixed effects
regression models, using logistic (for pupil-reported illness, roll-call absence and causes of absence outcomes),
binomial (pupil-reported absence, i.e. number of days
reported absent with offset of number of days of reporting), linear (SDQ-25, SAMNS-26, MPNS-36, SanQoL-5
and gender parity in enrolment), and ordered logistic

Page 5 of 12(subjective wellbeing) regression models as appropriate.
We additionally carried out a confirmatory analysis basedon the mean proportion of follow-ups with an episodeper pupil. Analyses included a random effect for school
and analyses based on repeated measures included an
additional random effect for pupil-level clustering, andassumed a constant treatment effect across time-points.
Primary estimates of effectiveness were calculated using
a basic model adjusting for stratification factors alone:school size and presence of kindergarten classes. Further
adjustments in secondary analyses were made for school
grade and gender, and a fully adjusted model was also
adjusted for school location by sub-city, and time-point
in analyses of repeated measures. Interaction tests wereused to examine the differential effect of the intervention
by gender, and across time-points on the three primary
outcomes. We examined factors associated with missing
outcome data (due to absence) at the final follow-up, andconducted exploratory sensitivity analyses of primary
outcomes adjusting for factors associated with missingness. Sensitivity analysis including all pupils enrolled in
the sentinel classes regardless of age was also performed.
We used Stata version 18.0 (StataCorp, College Station,
TX, USA) for all analyses.
This trial is registered with ClinicalTrials.gov, number
NCT05024890.

Results
Of the 143 schools due to receive the intervention in
2021/2022 or 2022/2023, 83 were eligible (Fig. 1) for thetrial. None of the 60 schools that were randomly selected
and consented to participation during school enrolment (2nd to 22nd November 2021) withdrew from thestudy. In total, 6455 pupils were enrolled at any point in
the trial, and 6,229 were later determined to be eligibleby age. Of those eligible, 5987 were enrolled during pupil
enrolment (23rd November to 22nd December 2021) andthe remaining 242 were enrolled during follow-up, due
to absence at enrolment (231) or joining the class midway through the academic year (11). Eighty-two pupils
left classes (dropped out of school) during the study,
most commonly due to transferring school or leaving thearea. The number of pupils contributing data to outcome
assessments is shown for each time-point in Fig. 1 andeach analysis table; a detailed summary of observations
for each outcome is found in Additional file 2: Table S1.
For roll-call attendance, 6166 (99.0%) pupils were registered in the sentinel classes (whether or not they were
present) during follow-up, i.e. had not dropped out
before the first follow-up. For pupil-reported repeatedmeasures, 6145 (98.6%) were present for at least one follow-up, balanced between study arms.

Bick et al. BMC Medicine

Fig. 1 Trial profile(2024) 22:348

Page 6 of 12

Bick et al. BMC Medicine(2024) 22:348

Of all eligible children enrolled, 52.6% were girls, themean age was 12.1 years (SD 2.5), few (27%) had at leasta basic sanitation service at home, but the majority (63%)
reported their household having at least a basic watersupply (Table 1). Pupils missing at the final follow-up
were similar to those present, except earning money forthe household was associated with missingness (datanot shown). There was a slight difference in school size
across arms; other characteristics were balanced. Of thegirls aged ten and above at the final follow-up, 48.5%(588/1212) in control schools and 45.3% (581/1063) inPage 7 of 12intervention schools had reached menarche, with themedian reported age at menarche 13 in both arms.
The mean proportion of follow-ups where pupils
reported diarrhoea in the past 7 days (co-primary healthoutcome) was 0.073 in control schools and 0.083 in intervention schools (Table 2), with no significant difference
between study arms in the primary analysis adjusting forclustering and stratification factors (aOR 1.15; 95% CI
0.84 to 1.59; p = 0.39). The mean proportion of follow-ups
reporting respiratory illness in the past 7 days (co-primary health outcome) was 0.278 in control schools andTable 1 Characteristics of participants and schools at enrolment
ControlIntervention

Characteristics of pupils
Number of pupils

3128

3101

Age in years, mean (SD)12.2 (2.5)

12.0 (2.5)

Female gender1674 (53.5%)1603 (51.7%)

Time taken to travel to school in min, median (IQR)

15 (10, 30)

15 (10, 30)

Household responsibilities  Collecting water

1666 (53.4%)

1741 (56.2%)   Earning money for household

75 (2.4%)

72 (2.3%)  Childcare973 (31.1%)

945 (30.5%)

Household members, median (IQR)

5 (4, 6)

5 (4, 6)

At least basic household water ­supplya

1912 (61.1%)

1993 (64.3%)

At least basic household s­ anitationb

857 (27.4%)

815 (26.3%)

30

30

Characteristics of schools
Number of schools
Sub-city  Addis Ketema

3 (10.0%)

2 (6.7%)  Akaky Kality

2 (6.7%)6 (20.0%)  Arada3 (10.0%)

4 (13.3%)  Bole2 (6.7%)

4 (13.3%)  Gulelle

3 (10.0%)

3 (10.0%)  Kirkos

5 (16.7%)

2 (6.7%)  Kolfe Keraniyo

5 (16.7%)

3 (10.0%)  Lemi Kura

1 (3.3%)1 (3.3%)  Lideta

1 (3.3%)3 (10.0%)   Nifas Silk Lafto

5 (16.7%)

2 (6.7%)

Number of grades, median (IQR)

8 (8, 8)8 (8, 8)

Number of pupils, median (IQR)

1112.5 (400, 1527)

935.5 (618, 1617)

Gender parity in ­enrolmentc, mean (SD)1.09 (0.11)

1.10 (0.10)

Number of disabled pupils, median (IQR)

33 (14, 75)

34 (18, 68)

Mean class size, mean (SD)48.8 (12.7)

46.3 (9.3)

Number of classes enrolled in the study  2

22 (73.3%)

19 (63.3%)  3

5 (16.7%)

10 (33.3%)  4

3 (10.0%)

1 (3.3%)aDefined as drinking water from an improved source, with collection time not more than 30 min roundtripbDefined as an improved facility not shared with other householdscAdjusted gender parity index [28]

Bick et al. BMC Medicine(2024) 22:348

Page 8 of 12

Table 2 Intervention effects on primary and secondary outcomesControlIntervention

Intervention effectOutcome

Pupils Mean proportion of follow-ups
with illness (SD)

Pupils Mean proportion of follow-ups
with illness (SD)aORa (95% CI)

p-value ICC

Pupil-reported diarrhoea
in the past 7 ­daysb

3075

0.073 (0.151)

3069

0.083 (0.160)

1.15 (0.83, 1.59)

0.39

0.088

Pupil-reported diarrhoea
in the past 2 days

3075

0.042 (0.112)3070

0.050 (0.127)

1.22 (0.82, 1.83)

0.32

0.13

Pupil-reported respiratory
illness in the past 7 ­daysb

3075

0.276 (0.269)

3070

0.248 (0.257)

0.84 (0.71, 1.00)

0.046

0.025

Pupil-reported respiratory
illness in the past 2 days

3075

0.187 (0.230)3070

0.171 (0.219)

0.88 (0.73, 1.06)

0.18

0.029

p-value ICC

Roll-call ­absenceb

Pupil-reported full-day
absence in past week

Pupils Mean proportion of follow-ups
absent (SD)

Pupils Mean proportion of follow-ups
absent (SD)aORa (95% CI)

3088

3078

1.07 (0.83, 1.38)

0.59

Pupils Mean proportion of school days
reported absent (SD)0.103 (0.171)

Pupils Mean proportion of school days
reported absent (SD)aORa (95% CI)

p-value ICC

3075

3070

1.01 (0.75, 1.36)

0.93

0.056 (0.090)

0.106 (0.171)

0.055 (0.082)

0.051

0.067

Pupils Mean score (SD)

Pupils Mean score (SD)aMD (95% CI)

p-value ICC

SDQ-15 total difficulties score(0–40)

1829

10.1 (6.0)

1675

10.0 (6.0)

0.03 (− 0.62, 0.68)

0.94

0.028

SAMNS-26 total score (0–100)545

69.1 (17.9)

438

72.3 (18.6)

3.32 (0.05, 6.59)

0.046

0.060

MPNS-36 total score (0–3)

530

1.92 (0.39)406

1.91 (0.39)− 0.01 (− 0.08, 0.06) 0.81

0.051

Note: Analyses include all eligible children with outcome data at the relevant follow-up. For repeated measures, we calculated a proportion of available follow-ups
with illness/absent for each participant, and the mean and SD of these proportions across participants are shown. Analyses were adjusted for stratification variables(school size < or ≥ 1200 pupils, and presence of a kindergarten), with further adjusted models reported in Additional file 2: Table S2. All analyses included a random
effect for school, and analyses based on repeated measures included an additional random effect for pupil-level clustering and assumed a constant treatment effectacross time-pointsaFor dichotomous outcomes, the estimated differences in means are reported in Additional file 2: Table S3bPrimary outcomes

0.248 in intervention schools, corresponding to a 16%
relative reduction in the odds of pupil-reported respiratory illness in the past 7 days during follow-up in the primary analysis (aOR 0.84; 95% CI 0.71 to 1.00; p = 0.046).
The mean proportion of follow-ups absent from roll-call
was similar between arms (0.103 in control schools vs.
0.106 in intervention schools), with no significant difference in odds of absence (aOR 1.07; 95% 0.83 to 1.38;
p = 0.59) in the primary analysis.
Models with further covariate adjustments produced
similar results (Additional file 2: Table S2), as did analysis based on mean differences in pupil-level proportions(Additional file 2: Table S3).
Among the secondary outcomes, effects on pupilreported diarrhoea and respiratory illness in the past
2 days were similar in direction to the respective 7-day
outcomes but with no evidence of differences between
arms (Table 2). Pupils reported absence at a much lower
rate than roll-call absence (the mean proportion ofschool days reported absent was 0.056 in control schools
and 0.055 in intervention schools), with no evidence of adifference between arms. We observed a small increase

in SAMNS-26 total score in the intervention arm vs. control of three points on a 0–100 scale (mean difference
3.32; 95% CI 0.05 to 6.59; p = 0.046). There was no evidence of differences in either the MPNS-36 total score or
the SDQ-25 total difficulties score between arms.
We observed no evidence of effects on other outcomes,
including causes of absence, pupil-reported earache (negative control for pupil-reported illness), subjective wellbeing measured through a smiley faces visual analogue
scale, menstrual health sub-scales, and gender parity inenrolment (Additional file 2: Table S4), with the exception of past-week absence due to diarrhoea (aOR 0.59;
95% CI 0.37 to 0.93; p = 0.024), which was very rarely
reported (mean proportion of follow-ups of 0.008 in controls schools vs. 0.005 in intervention schools).
There was some evidence of effect modification bygender (p = 0.021) for pupil-reported respiratory illness in the past 7 days, with a greater intervention effectobserved in boys (Fig. 2). Prevalence of pupil-reported
respiratory illness in the past week during pupil enrolment was similar between girls and boys in both intervention (32% vs. 31%; χ2 p = 0.42) and control (33% vs.

Bick et al. BMC Medicine(2024) 22:348

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Fig. 2 Gender-disaggregated intervention effects on primary outcomes

32%; χ2 p = 0.87) arms. Findings for pupil-reported diarrhoea and roll-call absence were consistent across genders (p-value for interaction 0.96 and 0.54, respectively).
There was no evidence of group-time interaction for
pupil-reported respiratory illness (p = 0.31), diarrhoea(p = 0.67) or roll-call absence (p = 0.89).
Sensitivity analyses including all children in enrolledclasses regardless of age, and adjusting for responsibility
for household income generation (predictor of missingness at final follow-up) both produced similar findings(Additional file 2: Table S5).

Discussion
In the WISE cluster-randomised trial, we found a borderline significant reduction in pupil-reported respiratory
illness in the past 7 days, and no evidence of reductions
in diarrhoea or absence from school. These results point
to the potential success of Project WISE at interrupting
the transmission of respiratory pathogens by increasing
handwashing with soap, as hand hygiene interventions
have been associated with reductions in risk of acute respiratory illness of 24% for school-aged children in LMICs[2]. This finding is notable in the context of the COVID19 pandemic, an active global threat during the study
period (2021–2022), suggesting that school-based WASH
can prevent disease amid social mixing at school, evenwhen pupils have limited WASH access at home.
The lack of impact on pupil-reported diarrhoea may
not be surprising given that schools received water andhygiene components but not intended upgraded toilet
facilities within the study duration—access to clean sanitation facilities that safely remove excreta can be criticalto interrupt transmission of faecal-oral pathogens [30].

Providing safe, private spaces to change may be more
important than menstrual products or sanitation technology in addressing menstruation-related absence[31]—one explanation for the lack of effect on girls’
absence and the inconsistent effects on menstrual healthoutcomes, with only a small increase in menstrual careself-efficacy observed. School absence and wellbeing are
multi-factorial; it seems feasible that the intervention(as received) may not have addressed enough factors to
observe psychosocial and educational impacts.
The mixed effects of the WISE intervention on illness
and absence are consistent with the existing literature[9], including multiple rigorous randomised trials [19,32–34]. Impacts of WASH in schools are often contextspecific and affected by factors such as local water accessor underlying disease prevalence in the population [9].
The high rates of past-week respiratory illness in thispopulation (mean proportion of follow-ups with theoutcome in the control arm 0.276) compared to otherprimary outcomes (0.073 and 0.103 for diarrhoea andabsence, respectively) may have contributed to observing
an effect for this outcome alone. We were unable to distinguish COVID-19 from other respiratory infections; it
is unknown whether this high prevalence would persist
in subsequent years.
Strengths of the study include the ‘open-cohort’design that allowed minimal participant attrition, andabsence triangulated through multiple measurement
approaches—we provide evidence that pupil-reported
absence is under-reported compared to roll-callabsence. The use of pupil-reported measures for healthoutcomes is a limitation; using more ‘objective’ measures, such as stool-based pathogen detection versus

Bick et al. BMC Medicine(2024) 22:348

self-reported diarrhoea [35], would help to minimise
reporting bias, and enable differentiation of COVID-19
versus other respiratory infections. Concerns aroundbias in measuring illness among attendees are mitigatedby the lack of differential absence rates between studyarms; however, it is possible some illnesses were missed
by not following absentees. Follow-up was limited
to one academic year for logistical reasons, so we areunable to evaluate the long-term impacts, or the additional effect of the sanitation component once received.
However, we note that cluster-randomised trials withmulti-year follow-up periods have also reported limited impacts on health outcomes [19, 32, 36]. With
one borderline significant effect among three primary
outcomes (without correction for multiple comparisons), we were unable to obtain strong evidence forthe effectiveness of the intervention. For practical reasons we were limited in the number of schools that
could be randomised; it is possible that the intervention had smaller effects only detectable with a larger
cluster-randomised trial. We are unable to explain thegreater impact of the intervention on respiratory illness among boys; there was no overall difference inodds of respiratory illness by gender at pupil enrolment(mid-intervention) nor during follow-up. More genderdisaggregated data on the impact of school-based programmes are needed to further explore this issue.

Conclusions
This study provides evidence that a school-based waterand hygiene intervention implemented on a large scale
across a city can impact respiratory illness among
schoolchildren and demonstrated the utility of unannounced visits for absence tracking. However, the greater
impact observed among boys remains unexplained, andfuture evaluations should include methods to differentiate pandemic and seasonal infection. Further researchis warranted to establish the relationships between
WASH-related illness and downstream educational outcomes—including illness-related and overall absence,educational progression, and gender parity in education—and strengthen understanding of the expected
impacts of WASH in schools across multiple domains.
Abbreviations
ICC	Intracluster correlation coefficient
LMIC	Low- and middle-income countries
MHM	Menstrual hygiene management
MPNS	Menstrual Practice Needs Scale
SAMNS	Self-efficacy in Addressing Menstrual Needs Scale
SanQoL	Sanitation-related quality of life
SDG	Sustainable Development Goals
SDQ	Strengths and Difficulties Questionnaire
WASH	Water, sanitation and hygiene
WISE	WASH in schools for everyone

Page 10 of 12

Supplementary Information
The online version contains supplementary material available at https://​doi.​
org/​10.​1186/​s12916-​024-​03558-x.
Additional file 1: Project WISE infrastructure and delivery, text accompanying Figures S1–S5. FigS1–Water storage tanks (left) and water filtration
system (right) installed in study schools. FigS2–Drinking water stations
installed in study schools. FigS3–Handwashing stations installed in study
schools. FigS4–Posters and signage at drinking water stations (left andcentre) and handwashing stations (right) installed in study schools. FigS5–
Approximate locations of 30 intervention (blue) and 30 control (orange)
schools enrolled in the WISE trial across Addis Ababa, Ethiopia.
Additional file 2. Tables S1–S5. Table S1–Number of participants andobservations included in assessment of each outcome at each time-point.
Table S2–Intervention effects on primary and secondary outcomes acrossthree models with various adjustments. Table S3–Analysis of mean differences for primary and secondary repeated binary outcomes aggregatedat the pupil level. Table S4–Intervention effects on other outcomes.
Table S5–Sensitivity analyses.
Acknowledgements
The authors would like to acknowledge the teachers, parents and pupilsof the 60 schools in Addis Ababa who participated in the study and gave
generously of their class time for this research. We also thank the Splash teams
in Addis Ababa and Seattle for their assistance in the conduct of the study
and coordination with schools. Lastly, we thank the survey staff from Holster
International Research and Development Consultancy for their considerable
efforts in data collection.
Authors’ contributions
SB contributed to methodology, formal analysis, accessed and verified underlying data, writing – original draft, writing – review & editing, decision to submit. AE contributed to project administration, methodology, writing – review& editing. CO, WA, EH and EA contributed to methodology, writing – review& editing. BL contributed to methodology, accessed and verified underlying data, writing – review & editing. OC contributed to conceptualisation,
methodology, writing – review & editing. RD contributed to conceptualisation,
methodology, supervision, writing – review & editing, decision to submit. All
authors read and approved the final manuscript.
Authors’ Twitter handles
Twitter handles: @SarahTBick (Sarah Bick); @ErinHunterPH (Erin C Hunter).
Funding
This study was funded by the Children’s Investment Fund Foundation, grant
number 1907–03868. The funder of the study had no role in study design,
data collection, data analysis, data interpretation, or writing of the report. The
corresponding author had full access to all the data in the study and had final
responsibility for the decision to submit for publication.
Availability of data and materials
Deidentified participant data, a data dictionary defining each field in theset, and code to reproduce analyses using Stata are available in the London
School of Hygiene & Tropical Medicine’s Data Repository (https://​doi.​org/​10.​
17037/​DATA.​00004​333).

Declarations
Ethics approval and consent to participate
The study protocol was approved by the London School of Hygiene & Tropical
Medicine Research Ethics Committee (reference 17761), and the National
Research Ethics Review Committee of Ethiopia (reference A/A/H/10H02/227)
prior to commencement of study activities. Under the direction of the study
investigators, Holster International Research and Development Consultancy
was responsible for data collection. School principals provided written
informed consent on behalf of all pupils in the school in loco parentis. Opt-out
forms were distributed to all parents/guardians of pupils in the selectedclasses. Pupils were excluded from data collection if their parent or guardian

Bick et al. BMC Medicine(2024) 22:348

returned the opt-out form at any point and were required to give oral assent
before each data collection activity.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Author details
1
Department of Disease Control, Faculty of Infectious and Tropical Diseases,
London School of Hygiene and Tropical Medicine, London, UK. 2 Holster
International Research and Development Consultancy, Addis Ababa, Ethiopia.
3
Department of Medical Statistics, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.
4
Department of Statistical Science, Faculty of Mathematical and PhysicalSciences, University College London, London, UK. 5 Independent Consultant, Addis Ababa, Ethiopia. 6 Department of Public Health Sciences, College
of Behavioral, Social and Health Sciences, Clemson University, Clemson, USA.
7
Department of International Health, Johns Hopkins Bloomberg Schoolof Public Health, Baltimore, USA. 8 Sydney School of Public Health, The University of Sydney, Sydney, Australia.
Received: 8 May 2024 Accepted: 13 August 2024

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