Public Health 222 (2023) 186e195

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Original Research

Inability to work following COVID-19 vaccinationea relevant aspect
for future booster vaccinations€user a, b, h, A. Gabel a, A. Ho€ hn a, T.-T. La^m c, L.B. Krone d, e,
J. Reusch a, b, h, I. Wagenha€ lken f, S. Frantz b, O. Kurzai c, g, U. Vogel a, c,
A. Frey b, A. Schubert-Unkmeir c, L. Do
a, c, ib, *, i, N. Petri
M. Kronea

Infection Control and Antimicrobial Stewardship Unit, University Hospital Wuerzburg, Wuerzburg, Germany
Department of Internal Medicine I, University Hospital Wuerzburg, Wuerzburg, Germany
Institute for Hygiene and Microbiology, University of Wuerzburg, Wuerzburg, GermanydDepartment of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UKe
University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, SwitzerlandfInstitute for Virology and Immunobiology, University of Wuerzburg, Wuerzburg, GermanygLeibniz Institute for Natural Product Research and Infection Biology e Hans-Knoell-Institute, Jena, Germanybca r t i c l e i n f o

a b s t r a c t

Article history:
Received 24 January 2023
Received in revised form
27 June 2023
Accepted 5 July 2023
Available online 8 August 2023

Objectives: COVID-19 vaccination is a key prevention strategy to reduce the spread and severity of SARSCoV-2 infections. However, vaccine-related inability to work among healthcare workers (HCWs) could
overstrain healthcare systems.
Study design: The study presented was conducted as part of the prospective CoVacSer cohort study.
Methods: This study examined sick leave and intake of pro re nata medication after the ﬁrst, second, andthird COVID-19 vaccination in HCWs. Data were collected by using an electronic questionnaire.
Results: Among 1704 HCWs enrolled, 595 (34.9%) HCWs were on sick leave following at least one COVID-19
vaccination, leading to a total number of 1550 sick days. Both the absolute sick days and the rate of HCWs on
sick leave signiﬁcantly increased with each subsequent vaccination. Comparing BNT162b2mRNA andmRNA-1273, the difference in sick leave was not signiﬁcant after the second dose, but mRNA-1273 induced asigniﬁcantly longer and more frequent sick leave after the third.
Conclusion: In the light of further COVID-19 infection waves and booster vaccinations, there is a risk ofadditional staff shortages due to postvaccination inability to work, which could negatively impact thealready strained healthcare system and jeopardise patient care. These ﬁndings will aid further vaccination campaigns to minimise the impact of staff absences on the healthcare system.
© 2023 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Keywords:
COVID-19 vaccination
Healthcare workers
Sick days
Inability to work

Introduction
The ongoing COVID-19 pandemic,1 with its high morbidity andaccompanying therapeutic demands, has drastically demonstrated
the urgency of a resilient public health system.2 Healthcare workers(HCWs) of all qualiﬁcations play a central role in the criticalAbbreviations: PCR, HCWs; PRN, VOC.
* Corresponding author. Department of Internal Medicine I, University Hospital
Wuerzburg, Oberdürrbacher Straße 6, 97080, Wuerzburg, Germany. Tel.: þ49 931
201 44987.
E-mail address: petri_n@ukw.de (N. Petri).
hboth authors contributed equally.
iboth authors contributed equally.

infrastructure needed to cope with the high SARS-CoV-2 infection
prevalence levels.3e6
The COVID-19 pandemic has a direct impact on the availabilityof public healthcare due to the persistent and non-negligible
burden of disease. The exceptional strain on health systems iscaused not only by the increasing number of patients but also by
the number of HCWs on sick leave due to a SARS-CoV-2 infection.7
COVID-19 vaccination has emerged as a key strategy to control
the spread and severity of SARS-CoV-2 infections, particularly among
HCWs. However, vaccine-related incapacity could overwhelm publichealthcare and must be addressed as part of this important prevention strategy. Vaccine-related staff absences must be consideredin light of future COVID-19 booster vaccination campaigns and thechallenges posed by the continuing COVID-19 pandemic.8

https://doi.org/10.1016/j.puhe.2023.07.008
0033-3506/© 2023 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

€user, A. Gabel et al.
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Public Health 222 (2023) 186e195

Previous studies have described increased staff absences afteradministration of mRNA-1273 compared to BNT162n2mRNA, as
well as in younger and female HCWs. All studies published to datehave examined only basic immunisation, including administrationof the ﬁrst and second COVID-19 vaccine doses. To date, evidence isinsufﬁcient to predict the impact of COVID-19 vaccine-related incapacity on healthcare systems.9e11
The main goal of this study was to examine the number of sickdays as well as the rate of staff absences after the ﬁrst, second, andthird dose of COVID-19 vaccination among HCWs. We also performed a detailed analysis to assess the intake of pro re nata (PRN)
medication following vaccinations and examined the impact ofvaccine type, gender, age, and profession on the inability to work
following COVID-19 vaccination.

were included, in accordance with the recommendations of theGerman Standing Committee on Vaccination (STIKO) during thedata-collection period.13
Mainly HCWs from a single tertiary hospital were involved inthis study, but HCWs from surrounding hospitals and medical
surgeries were also included.
The questionnaire including questions on sick leave and postvaccination medication needs was conducted using the platform
Research Electronic Data Capture (REDCap), projectredcap.org.14
Occupational groups were asked in the following sections:“nursing”, “physicians”, “other HCWs with patient contact”, and“other HCWs without any patient contact”.

Methods

The study protocol was approved by the Ethics committee of the
University of Wuerzburg in accordance with the Declaration of
Helsinki (ﬁle no. 79/21).

Ethical approval

Study design
The study presented was conducted as part of the prospective
CoVacSer cohort study, which examines the progression of AntiSARS-CoV-2-Spike IgG levels as well as quality of life and work
ability in HCWs after COVID-19 vaccination and/or SARS-CoV-2
infection.
Participants who met all of the following inclusion criteria wererecruited for the CoVacSer study: (i) age 18 years, (ii) written
informed consent, (iii) minimum interval of 14 days after ﬁrst
conﬁrmation of SARS-CoV-2 infection by polymerase chain reaction
and/or at least one dose of COVID-19 vaccination regardless of
vaccination schedule, and (iv) employment in healthcare sector.
Vaccination schedules with vaccines that were not licensed by theEuropean Medicines Agency (EMA) during the data collection
period were excluded from the data analysis according to the study
protocol.12
Under the study protocol, participants were followed up at set
intervals for 24 months after the last SARS-CoV-2 immunising
event, with the follow-up cycle restarting with each new SARSCoV-2 infection or COVID-19 vaccination. Serum blood samples incombination with pseudonymised digital questionnaires werecollected both at study enrolment and at each follow-up.
Since the 18th of November 2021, COVID-19 booster vaccinations
have been ofﬁcially offered at the earliest six months after the second
dose of COVID-19 vaccine or after the last SARS-CoV-2 infection,according to recommendation of the German Standing Committee
on Vaccination (STIKO). For immunocompetent adults aged 18e30
years, a single dose of BNT162b2mRNA (30 mg) was recommended;
for those aged 30 years, a single dose of BNT162b2mRNA (30 mg) or
half a dose of mRNA-1273 (50 mg). Both heterogeneous and homologous vaccine combinations were recommended.13

Statistics
For determining statistical differences, such as sick leave andintake of PRN medication, within pairwise comparisons of HCWs’
subpopulations, exact Fisher tests were performed. For comparing
the days of sick leave between HCWs grouped by COVID-19
vaccination doses, gender, and profession, Wilcoxon rank-sum
tests were performed. Mean days of sick leave after vaccinations
were presented as bar graphs with error bars indicating one
standard deviation. The percentage of HCWs were also presented
as bar graphs, whereas the error bars indicate the upper conﬁdence interval based on a binomial distribution. To account for
multiple testing, P-values were corrected based on the
BenjaminieYekutieli procedure.15 Using a second-order inhomogeneous Markov model, the relationships between the outcomes(healthy or sick leave) of various vaccination events (ﬁrst dose,
second dose, third dose) were estimated. The statistical analyses
were performed with the statistical programming language R(version 4.2.1).
The reproducible script and the statistical analysis can beaccessedunder
https://github.com/AlexGa/Inability-to-workfollowing-COVID-19-vaccination-among-healthcare-workers.
Results
Participant recruitment and characterisation of the study
population
From the 29th of September 2021 to the 27th of March 2022, 1831
individuals participated and completed the study questionnaire.
A total of 1704 (93.1%) individuals were eventually included in
the data analysis. Seventy-seven participants did not meet the
study inclusion criteria according to the study protocol, 42 wereconvalescent of SARS-CoV-2 infection prior to their ﬁrst COVID-19
vaccination, and eight had received a COVID-19 vaccine otherthan the ones considered. A detailed overview of excluded participants is provided in Fig. 1.
A total of 81.0% (1379/1704) of the included participants identiﬁed as female, 19.0% (325/1704) as male, with an overall medianage of 39 (interquartile range: 29e52) years.
Overall, all 1704 included participants received at least a ﬁrst
dose of COVID-19 vaccine, 99.6% (1698/1704) received a second
dose, and 79.5% (1355/1704) a third one, without any SARS-CoV-2
infection prior to the respective vaccine administration. A total of

Data collection
The data collection period ranged from the 29th of September
2021 to the 27th of March 2022.
Only participants who had been vaccinated at least once against
COVID-19 without convalescence of SARS-CoV-2 before their ﬁrst
vaccination were included into data analysis. All further follow-up
examinations were incorporated as long as participants were notyet infected with SARS-CoV-2.
For
the
ﬁrst
vaccination,
the
COVID-19
vaccines
BNT162b2mRNA, mRNA-1273, ChAdOx1-S, and Ad26. CoV2eS
were considered. For the second and third vaccinations, only participants who had received BNT162b2mRNA and/or mRNA-1273

187

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Public Health 222 (2023) 186e195

Sick leave after the ﬁrst dose of COVID-19 vaccination among HCWs
After the ﬁrst COVID-19 vaccination dose, a total of 3.8% (51/1704)
HCWs were on sick leave, 3.1% (51/1664) of those vaccinated with
BNT162b2mRNA (0.1 mean sick days, 95 absolute sick days), none incase of mRNA-1273 administration, 52.4% (11/21) among ChAdOx1S-administered HCWs (1.1 mean sick days, 22 absolute sick days),and 28.6% (2/7) of those vaccinated with Ad26. CoV2eS (1.0 meansick days, 7 absolute sick days).
The proportion of HWCs who were absent from work after a ﬁrst
dose of ChAdOx1-S was signiﬁcantly higher than that afteradministration of BNT162b2mRNA (P < 0.0001) or mRNA-1273(P < 0.05; Fig. 2A). Mean sick days after a ﬁrst dose of ChAdOx1-S
were signiﬁcantly more than that after administration of
BNT162b2mRNA (P < 0.0001) or mRNA-1273 (P < 0.05); mean sickdays after a ﬁrst dose of Ad26. CoV2eS were signiﬁcantly longer
than that after administration of BNT162b2mRNA (P < 0.001;
Fig. 2D).

97.7%(1664/1704)
participants
were
vaccinatedwith
BNT162b2mRNA for the ﬁrst administration, 0.7% (12/1704) with
mRNA-1273, 1.2% (21/1704) with ChAdOx1-S, and 0.4% (7/1704)
with Ad26. CoV2eS. BNT162b2mRNA accounts for 98.9% (1680/1698) of the second COVID-19 inoculations, whereas mRNA-1273
constitutes 1.1% (18/1698). In the third COVID-19 vaccinationdose, BNT162b2mRNA amounts to 81.0% (1100/1355) and mRNA1273 to 19.0% (255/1355; Fig. 1).
The enrolled HCWs were distributed among the four occupational groups as follows: 34.9% (594/1704) nursing, 18.6% (317/1704) physicians, 22.0% (375/1704) other HCWs with patient
contact, and 24.5% (417/1704) other HCWs without any patient
contact. A detailed characterisation by profession is presented inTable 1.
Sick leave separated by number of doses of COVID-19 vaccination
In total, absenteeism due to vaccine-related illness resulted in an
absolute number of 1550 sick days in the cohort of 1704 participants for the entirety of COVID-19 vaccinations administered.
The extent of sick leave following subsequent doses of COVID-19
vaccination can be expressed in the rate of cumulative sick days per1000 HCWs. In our representative cohort, we found 74.5 sick days
per 1000 HCWs for the ﬁrst vaccination dose, 437.5 for the second
dose, and 510.0 for the third dose.

Sick leave after the second dose of COVID-19 vaccination among
HCWs
In the case of the second COVID-19 vaccination, 21.8% (370/1698)
of HWCs reported incapacity for work, 21.7% (365/1680) within thegroup of HCWs vaccinated with BNT162b2mRNA (0.4 mean sickdays, 725 absolute sick days) and 27.8% (5/18) among HCWs

Fig. 1. Recruitment of study participants and characterisation of ﬁnal study population separated by number of doses and type of COVID-19 vaccine.
188€user, A. Gabel et al.
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Public Health 222 (2023) 186e195

Table 1
Characterisation of the study population separated by profession, percentages indicate the share of the study cohort. Age and body mass index are reported as medians withinterquartile ranges in brackets.
Characteristic

Nursing

Physicians

HCWs with a ﬁrst dose
594 (34.9%)317 (18.6%)
of COVID-19
vaccination without
SARS-CoV-2
convalescence592 (34.9%)317 (18.7%)
HCWs with a second
dose of COVID-19
vaccination without
SARS-CoV-2
convalescence
462 (34.1%)
248 (18.3%)
HCWs with a third
dose of COVID-19
vaccination without
SARS-CoV-2
convalescence
Gendermale
77 (13.0%)
127 (40.1%)
female517 (87.0%)
190 (59.9%)
Age (IQR) [years]
39 (27e51)
33 (30e42)24.3 (21.9e28.1)
22.7 (20.8e24.5)
BMI (IQR) [kg/m2]
smoking HCWs
120 (20.2%)
15 (4.7%)
Distribution of post-vaccination sick days
45
17
Cumulative absolute
number of sick days
after the ﬁrst
COVID-19
vaccination
269
82
Cumulative absolute
number of sick days
after the second
COVID-19
vaccination
259
65
Cumulative absolute
number of sick days
after the third
COVID-19
vaccination
0.1
0.1
Mean sick days afterﬁrst dose of COVID19 vaccination
0.5
0.3
Mean sick days after
second dose of
COVID-19
vaccination
0.4
0.2
Mean sick days after
third dose of
COVID-19
vaccination
Share of HCWs per occupational group with postvaccination PRN medication
First dose of COVID-19
159 (26.8%)
55 (17.4%)
vaccination
Second dose of COVID309 (52.2%)
128 (40.4%)
19 vaccination
Fhird dose of COVID403 (87.2%)
217 (87.5%)
19 vaccination
First COVID-19 vaccination: distribution of vaccines
BNT162b2mRNA
583 (34.2%)
310 (18.2%)
mRNA-1273
2 (0.1%)2 (0.1%)ChAdOx1-S
7 (0.4%)5 (0.3%)
Ad2.COV2eS
2 (0.1%)0
Second COVID-19 vaccination: distribution of vaccines
BNT162b2mRNA
586 (34.5%)314 (18.5%)
mRNA-1273
6 (0.4%)3 (0.2%)
Third COVID-19 vaccination: distribution of vaccines
BNT162b2mRNA
381 (28.1%)
232 (17.1%)
mRNA-1273
81 (6%)
16 (1.2%)

Other HCWs with patient contact

Other HCWs without any patient contact

375 (22.0%)417 (24.5%)374 (22.0%)414 (24.4%)

293 (17.6%)

351 (25.9%)

43 (11.5%)
332 (88.5%)
42 (30e55)
23.8 (21.2e27.2)
44 (11.7%)

77 (18.5%)340 (81.5%)
42 (32e54)
23.6 (21.5e26.6)
32 (7.7%)

44

18

217

167

200

167

0.1

0.0

0.6

0.4

0.5

0.4

283 (24.5%)

338 (18.9%)

179 (47.9%)

168 (40.6%)

255 (87.0%)

289 (82.3%)

366 (21.5%)
3 (0.2%)5 (0.3%)1 (0.1%)404 (23.7%)
5 (0.3%)4 (0.2%)4 (0.2%)371 (21.9%)
3 (0.2%)408 (24.0%)
6 (0.4%)235 (17.4%)
58 (4.3%)

251 (18.5%)
100 (7.4%)

BMI: body mass indes; HCWs: healthcare workers; IQR: interquartile range

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Fig. 2. Comparison of sick leave depending on the number of doses and type of COVID-19 vaccine. A portrays the relative proportion of healthcare workers on sick leave stratiﬁed bynumber of doses and type of COVID-19 vaccine. B pictures the average days on sick leave stratiﬁed by number of doses and gender, C by number of doses and profession, D by
number of doses and type of COVID-19 vaccine. E visualises the overall average sick leave days stratiﬁed by number of doses and F the relative share of HCWs on sick leave separated
by number of doses. A&F: Error bars indicate the corresponding conﬁdence interval: B-E: Bar height and error bars indicate group means and one standard deviation. *: P < 0.05, **:P < 0.01, ***: P < 0.001. ****: P < 0.0001.

Post-vaccination sick leave among HCWs, separated by gender
Separated by gender, 4.1% female HCWs (56/1379) were on sickleave after the ﬁrst COVID-19 vaccination, 23.7% (325/1374)
following the second, and 29.7% (234/1121) after the third vaccine
administration. In case of male HCWs, 1.5% (5/325) were on sickleave after the ﬁrst vaccination, 11.7% (38/324) after the second, and17.1% (40/194) after the third one (Fig. 2B).
Overall, 526 of 1379 (38.1%) female and 69 of 325 (21.2%) male
HCWs were on sick leave, showing a signiﬁcant ratio of absent female compared to male HCWs (P < 0.0001). Separated by dose of
COVID-19 vaccinations for all three administrations, female HCWs
showed signiﬁcantly higher mean sick days (P < 0.05 for the ﬁrst,
P < 0.0001 for the second, P < 0.001 for the third one; Fig. 2B).

administered with mRNA-1273 (0.6 mean sick days, 10 absolute sickdays).
After the second dose of COVID-19 vaccination, there was no
signiﬁcant difference in the proportion of HCWs on sick leave ormean sick days after administration of BNT162b2mRNA or mRNA1273 (Fig. 2A and D).
Sick leave after the third dose of COVID-19 vaccination among
HCWs
Following the third dose of COVID-19 vaccination, overall, 27.9%(378/1355) of HCWs were off sick, 24.7% (272/1100) of thosevaccinated with BNT162b2mRNA (0.4 mean sick days, 487 absolutesick days) and 41.6% (106/255) of participants who received mRNA1273 (0.8 mean sick days, 204 absolute sick days).
After a third COVID-19 vaccination dose, signiﬁcantly more
HCWs were on sick leave after mRNA-1273 administration thanafter BNT162b2mRNA administration (P < 0.0001; Fig. 2A), andmean sick days after mRNA-1273 were signiﬁcantly more than after
BNT162b2mRNA administration (P < 0.0001; Fig. 2A and D).

Post-vaccination sick leave among HCWs, separated by occupationalgroupsSeparated by occupational groups, among nursing HCWs, 3.4%
were on sick leave following the ﬁrst COVID-19 vaccination (0.1
mean sick days, 45 absolute sick days), 22.3% after the second (0.5190

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Public Health 222 (2023) 186e195

third doses; Fig. 2F) as well as in the mean sick leave (P < 0.0001,
comparing ﬁrst and second doses; P < 0.0001, comparing ﬁrst andthird doses; P < 0.001, comparing second and third doses; Fig. 2E).

mean sick days, 269 absolute sick days), and 25.6% after the third
one (0.4 mean sick days, 259 absolute sick days).
Among physicians, 2.8% were on sick leave after the ﬁrst (0.05
mean sick days, 17 absolute sick days), 15.5% after the second (0.3
mean sick days, 82 absolute sick days), and 17.3% after the third
vaccination (0.2 mean sick days, 65 absolute sick days).
Among other HCWs with patient contact, 5.3% were off sick after
the ﬁrst vaccination (0.1 mean sick days, 44 absolute sick days),
24.3% after the second (0.6 mean sick days, 217 absolute sick days),and 36.9% after the third one (0.5 mean sick days, 200 absolute sickdays).
Among HCWs without any patient contact, 2.9% were on sickleave following the ﬁrst vaccination (0.0 mean sick days, 18 absolute sick days), 22.7% after the second (0.4 mean sick days, 167
absolute sick days), and 29.6% after the third administration (0.4
mean sick days, 167 absolute sick days; Fig. 2D).
At the second COVID-19 vaccination, the mean number of sickdays was signiﬁcantly higher among nursing HCWs than among
physicians (P < 0.05); physicians were signiﬁcantly less likely to
be on sick leave than other HCWs with patient contact (P < 0.05)
and then other HCWs without any patient contact (P < 0.05;
Fig. 2C).
Following the third COVID-19 vaccination, nurses recorded
signiﬁcantly longer mean sick leave than physicians (P < 0.05) but
fewer mean sick days than other HCWs with patient contact(P < 0.05); physicians had signiﬁcantly shorter sick leave than other
HCWs with (P < 0.0001) and without patient contact (P < 0.01;
Fig. 2C).

Comparison of BNT162b2mRNA and mRNA-1273 as booster
vaccines in HCWs aged 30 years
Since mRNA-1273 was ofﬁcially recommended as a booster
vaccine in Germany only for individuals at least 30 years of age,13 anage-adjusted subgroup analysis of the third COVID-19 vaccinationconsidering only HCWs aged 30 years was conducted (Table 2).
Within this subgroup of HCWs aged 30 years, after the third
COVID-19 vaccination, 23.7% (191/806) inoculated with
BNT162b2mRNA were off sick (0.4 mean sick days, 341 absolutesick days) compared to 40.9% (103/252) of HCWs vaccinated with
mRNA-1273 (0.8 mean sick days, 204 absolute sick days).
Thus, mRNA-1273 administration was responsible for a signiﬁcantly higher proportion of HCWs on sick leave than
BNT162b2mRNA (P < 0.0001; Fig. 3A); also, the mean number ofsick days was signiﬁcantly higher among mRNA-1273 booster
vaccinees (0.8 mean sick days, 202 absolute sick days) than among
HCWs administered with BNT162b2mRNA (0.3 mean sick days, 902
absolute sick days) (P < 0.0001, Fig. 3B).
Post-vaccination sick leave in relation to PRN medication
After administration of the ﬁrst COVID-19 vaccine dose, a total of
22.6% (385/1704) HCWs reported intake of PRN medication, after
the second dose 46.2% (784/1698), and after the third dose 86.0%(1165/1355; Fig. 4A).
The proportion of HCWs using PRN medication after the ﬁrst
vaccine dose was 21.9% (365/1668) for BNT162b2mRNA, 8.3% (1/12)
for mRNA-1273, 76.2% (16/21) for ChAdOx1-S and 42.9% (3/7) for
Ad26. CoV2eS.
Following the second COVID-19 vaccination, 46.1% (774/1680) of
HCWs vaccinated with BNT162b3mRNA required PRN medication,
55.6% (10/18) in case of mRNA-1273.
After the third dose, the proportion of HCWs using PRN medication was 89.2% (981/1100) for BNT162b2mRNA-vaccinated and72.2% (184/255) for mRNA-1273-vaccinated.

Overall sick leave after the ﬁrst, second, and third dose of COVID-19
vaccination among HCWs
Overall, 3.8% (51/1704) of HCWs were on sick leave (0.1 averagesick days) after the ﬁrst dose of COVID-19 vaccination, 21.8% (370/1698; 0.4 average sick days) after the second, and 27.9% (378/1355;
0.5 average sick days) after the third one. An analysis of the relationships between the outcomes (healthy or sick leave) of thevarious vaccination events (ﬁrst dose, second dose, third dose) are
shown in the Supplementary Results. With each additional dose,
there was a signiﬁcant increase in the proportion of HCWs on sickleave (P < 0.0001, comparing ﬁrst and second doses; P < 0.0001,
comparing ﬁrst and third doses; P < 0.0001, comparing second andTable 2
Characterisation of the study population aged 30 years at the time of the third COVID-19 vaccination; percentages indicate the share of the subcohort of HCWs aged 30years, separated by vaccination. Age and body mass index are reported as medians with interquartile ranges in brackets.
HCWs with a third dose of COVID-19 vaccine, aged 30
years

BNT162b2mRNA

mRNA-1273

Absolute number of study participants
Gender806 (76%)
159 (19.7%)
647 (80.3%)
46 (37e55)
24.2 (21.8e27.5)
102 (12.7%)341

252 (24%)
34 (13.5%)
218 (86.5%)
46 (39e55)
23.8 (21.5e27.1)
24 (9.5%)204

193 (24.0%)

106 (42.1%)

75 (9.3%)

71 (28.2%)

258 (24.4%)
175 (16.6%)
175 (16.6%)
197 (18.6%)

80 (7.6%)
15 (1.4%)
58 (5.5%)
99 (9.4%)

Male
FemaleAge (IQR) [years]
BMI (IQR) [kg/m2]
Smoking [absolute number]
Cumulative number of postvaccination sick days after
COVID-19 booster vaccination
Number of HCWs on post-vaccination sick leave after
COVID-19 booster vaccination
HCWs with postvaccination PRN medication after
COVID-19 booster vaccination
Distribution to occupational groups
Nursing
Physicians
Other HCWs with patient contact
Other HCWs without any patient contact
BMI: body mass indes; HCWs: healthcare workers; IQR: interquartile range; PRN: pro re nata191

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comparison to the group of other HCWs with patient contact after
the second vaccination (P < 0.05; Fig. 4D).
Discussion
Overall, COVID-19 vaccination caused a relevant number of sickdays among HCWs. HCWs who were administered the mRNAbased vaccines BNT162b2mRNA and mRNA-1273 as their ﬁrst
dose of COVID-19 vaccination had little postvaccination sick leave.
In contrast, a higher number of HCWs who were administered
ChAdOx1-S or Ad26. CoV2eS as their ﬁrst COVID-19 vaccination
were subsequently on sick leave. The ﬁrst dose of ChAdOx1-S
caused a signiﬁcantly higher rate of sick leave than the mRNAbased vaccines, and we observed a similar, albeit not statisticallysigniﬁcant, result in the small group (n ¼ 7) of HCWs receiving
Ad26. CoV2eS. Comparing BNT162b2mRNA and mRNA-1273, theadministration of mRNA-1273 resulted in a signiﬁcantly higher
rate of postvaccination sick leave after the third vaccination dose,with a similar trend for the second vaccination dose. The higher
rate of sick leave might be explained by differences in vaccine
composition. Following mRNA-1273 vaccination, increased antipoly (ethylene) glycol antibodies have been associated withincreased reactogenicity.16 A comparatively higher rate of PRN
medication intake after BNT162b2mRNA vaccination could have
reduced the rate of sick leave. Previous studies report that theimmunogenicity of mRNA-1273 with its proportionally higher
dosage exceeds that of BNT162b2mRNA and leads to a more
pronounced vaccination response.17,18 Our ﬁnding that mRNA1273 causes more sick leave supports these results and is very
robust as the higher rate of sick leave is signiﬁcant in the overall
analysis and in the more homogenous subgroup analysis ofenrolled HCWs aged 30 years.
In contrast to the ﬁrst COVID-19 vaccine dose, the second dose
resulted in an increase both in the rate of HCWs on sick leave and in
the average duration of sick leave, which further intensiﬁed after
the third dose, respectively.
As illustrated by the cumulative sick days, COVID-19 vaccination
has a non-negligible impact on the staff availability in the healthsector. Albeit that COVID-19 vaccination is undeniably an important
infection prophylaxis for HCWs, which aims to avoid quarantineand infection-related staff shortages, the vaccination also causes a
temporary relevant impairment of staff availability due to sickness
absences. The economic leverage of these sickness-related absences, due to limited treatment capacities of hospitals, should befurther considered.19e21
The observed rise in sick leave with increasing repetitions of
COVID-19 vaccinations might be explained by an immune response
boost that is ampliﬁed with each subsequent vaccination. This
could lead to an augmentation of vaccine-related reactions causingside effects and incapacity for work, which is in line with previous
ﬁndings of increasing humoral and T-cellular immunogenicity as
well as with reports about more vaccine-related side effects withrepeated vaccinations.8,22 Comparison of different occupationalgroups among the HCWs revealed that physicians spent fewer dayson sick leave after the second and third vaccination than otherprofessions. In addition, the lowest rate of postvaccination drug
intake was reported among physicians. In comparison, the rates ofsick leave as well as PRN medication intake were higher amongnurses. The increased use of medication might be an indicator of
more severe side effects and hence inability to work. This difference
might be explained by demographic variables such as age, genderand health status (e.g., body mass index). In addition, the different
work routine of the nursing and medical staff, which entails ahigher physical burden for the nursing staff, might further explain
the higher sickness rate among nurses. Furthermore, signiﬁcantly

Fig. 3. Comparison of sick leave depending on the number of doses of COVID-19
vaccine, adjusted for healthcare workers aged 30 years. A portrays the relative
number of healthcare workers on sick leave administered with mRNA-1273, B theaverage days on sick leave separated by COVID-19 vaccine, both stratiﬁed by number ofdoses of COVID-19 vaccine. Bar height and error bars indicate group means and one
standard deviation. ****: P < 0.0001.

After the ﬁrst vaccine dose, HCWs reported a signiﬁcantly higher
rate of medication use after administration of ChAdOx1-S compared
to both BNT162b2mRNA (P < 0.0001) and mRNA-1273 (P < 0.01).
After the third dose, a signiﬁcantly higher percentage of HCWs
vaccinated with BNT162b2mRNA reported the use of PRN medication than HCWs vaccinated with mRNA1273 (P < 0.0001; Fig. 4B).
Separated by gender, 24.0% (331/1379) of female and 16.6% (54/325) of male HCWs took PRN medication after the ﬁrst COVID-19
vaccination, 49.6% (682/1374) female and 31.5% (102/324) male
HCWs after the second vaccine administration, and 86.0% (964/1121) female and 85.9% (201/234) male HCWs after the third one.
Female HCWs had a signiﬁcantly higher proportion of postvaccination medication use after the ﬁrst (P < 0.01) and second(P < 0.0001) administration of COVID-19 vaccination than male
HCWs. No signiﬁcant difference was found between female andmale HCWs for the third COVID-19 vaccination (Fig. 4C).
By occupation, 26.8% (159/594) of nurses, 17.4% (55/317) of
physicians, 24.5% (283/375) of other HCWs with, and 18.9% (338/417) of HCWs without any patient contact indicated the use of PRN
medication following the ﬁrst COVID-19 vaccination. For the second COVID-19 vaccination, 52.2% (309/592) of nurses, 40.4% (128/317) of physicians, 47.9% (179/374) of other HCWs with, and 40.6%(168/414) of HCWs without any patient contact reported the use of
PRN medication. Regarding the third COVID-19 vaccination, 87.2%(403/462) of nurses, 87.5% (217/248) of physicians, 87.0% (255/293)of other HCWs with, and 82.3% (289/351) of HCWs without patient
contact used PRN medication (Table 1).
A signiﬁcantly higher share of enrolled nurses than physicians
reported taking medication PRN after the ﬁrst (P < 0.05) and second(P < 0.05) administration of COVID-19 vaccine, as well as in192

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Public Health 222 (2023) 186e195

Fig. 4. Postvaccination pro re nata medication, separated by the number of doses, type of COVID-19 vaccine, gender, and profession. A portrays the percentage of healthcare workers
with pro re nata medication after COVID-19 vaccine administration, separated by the number of doses, B separated by the number of doses and type of vaccine, C separated bynumber of doses and gender, and D separated by the number of doses and profession. Bar height and error bars indicate group means and upper border of conﬁdence interval. *:P < 0.05, **: P < 0.01, ****: P < 0.0001.

and Ad26. CoV2eS (n ¼ 7) in our study was small, and these two
vaccines were only used for the ﬁrst COVID-19 vaccination dose. As
the focus of our study was on mRNA-based COVID-19 vaccines, ourresults on sick leave after administration of ChAdOx1-S and Ad26.
CoV2eS should be interpreted with caution. Individuals immunised with the COVID-19 subunit vaccine NVX-CoV2373 were notincluded in this study as it was approved by the EMA after the study
recruitment period and was not recommended for a third vaccine
dose in Germany in individuals without contraindication for theuse of mRNA vaccines. Furthermore, due to the study period, themeanwhile available Omicron variant of concerneadapted, bivalent
COVID-19 vaccines are not included in the study. However, all ofthese limitations mentioned are direct consequences of the real-life
study setting, which underlines the transferability of the data and isa particular strength of our study.
In conclusion, inability to work following COVID-19 vaccination
among HCWs is an important and not-negligible aspect of this vital
infectioneprevention measure. Staff absences related to vaccination are considerably shorter than those after COVID-19 infection.25
Therefore, vaccine-related absence from work cannot be an argument for nonvaccination. However, vaccination-related staff absences can have a direct impact on healthcare capacity and place anadditional burden on an already understaffed healthcare systemdealing with demographic change, the additional burden of COVID-

fewer male than female HCWs used PRN medication after the ﬁrst
and second COVID-19 vaccination.
Our study has some relevant limitations. Since HCWs wereselected as study population, the collective is predominantly female, with women accounting for 81.0% of all participants,
reﬂecting the typical sociodemographic composition of HCWs in
Germany.23 Data on side effects and sick leave were collected
retrospectively, so a potential inﬂuence of recall bias and subjectivity cannot be ruled out. Dosage and time of PRN medication
intake after vaccination was not queried. The number of sick days
after vaccination was not evaluated separately for working days andweekends or holidays, which could reduce the extent of sick leave if
HCWs were incapable on their days off. Due to varying vaccine
availability and the recommendations of the German Standing
Committee on Vaccination (STIKO),13,24 the frequencies of thedifferent COVID-19 vaccines in our cohort are unequally distributed
for the ﬁrst, second, and third vaccinations, respectively; however,this reﬂects a real-life scenario. Since the federal recommendation
for administration of mRNA-1273 as a booster vaccine wasrestricted to individuals who were 30 years of age,13 data on sickleave among HCWs younger than 30 years vaccinated with mRNA1273 as booster vaccine are lacking. Of all the COVID-19 vaccinesconsidered, BNT162b2mRNA was the most frequently administeredvaccine. The number of HCWs vaccinated with ChAdOx1-S (n ¼ 21)
193

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J. Reusch, I. Wagenha

Public Health 222 (2023) 186e195

the manuscript. We miss him as an enthusiastic colleague andfriend who showed a great dedication to his work, family, andfriends.

19 patients, and shortages of qualiﬁed staff, especially nurses. To
ensure patient safety and avoid work overload, staff shortages due
to SARS-CoV-2-infected HCWs must be avoided. Our study provides
important data to estimate the burden of sick leave among HCWs
following COVID-19 vaccination. Our results provide representative
data that will inform the planning of vaccination campaigns andprovide a rational for optimisation measures such as the staggeringof vaccination offers. In view of the planned COVID-19 booster
vaccinations with a fourth or ﬁfth dose, our data on the rise of sickleave with repeated vaccine doses highlight the need to closely
monitor vaccine-related incapacity to work during the early stagesof the vaccination campaigns.

Data-sharing Statement
The reproducible script of all statistical analyses can be accessedat https://github.com/AlexGa/Inability-to-work-following-COVID19-vaccination-among-healthcare-workers.
Additional data that underlie the results reported in this article,
after deidentiﬁcation (text, tables, ﬁgures, and appendices) as wellas the study protocol, statistical analysis plan, and analytic code are
made available to researchers who provide a methodologicallysound proposal to achieve aims in the approved proposal onrequest to the corresponding author.

Author statements
Ethical approval

Appendix A. Supplementary data

The study protocol was approved by the Ethics committee of the
University of Wuerzburg in accordance with the Declaration of
Helsinki (ﬁle no. 79/21).

Supplementary data to this article can be found online athttps://doi.org/10.1016/j.puhe.2023.07.008.

Funding
References
This study was partially funded by the German Federal Ministryof Education and Research (BMBF) as part of the Network University Medicine: „NaFoUniMedCovid19“ Grant No: 01KX2021, Project: “Bundesweites Forschungsnetz Angewandte Surveillance undTestung” (B-FAST). The study was further supported by the Free
State of Bavaria with COVID-research funds provided to the University of Würzburg, Germany. Nils Petri is supported by theGerman Research Foundation (DFG) funded scholarship UNION
CVD. Lukas B. Krone is supported by the Wellcome Trust (grant-No
203971/Z/16/Z) and Hertford College, Oxford, UK.

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Role of funding sourceThis study was initiated by the investigators. The sponsoring
institutions had no function in study design, data collection, analysis, and interpretation of data as well as in the writing of themanuscript. All authors had unlimited access to all data. Julia
Reusch, Isabell Wagenh€
auser, Alexander Gabel, Manuel Krone, andNils Petri had the ﬁnal responsibility for the decision to submit for
publication.
Competing interests
MK receives honoraria from GSK and Pﬁzer outside the submitted work. All other authors declare no potential conﬂicts ofinterest.
Author contributions
All authors had unlimited access to all data. JR, IW, AG, MK, andNP take responsibility for the integrity of the data and the accuracyof the data analysis.
Conception and design: TTL LK, AF, ASU, LD, SF, OK, UV MK, NP.
Trial management: JR, IW, AH, MK, NP.
Statistical analysis: JR, IW, AG.
Obtained funding: OK, UV.
First draft of the manuscript: JR, IW, AG, LK, MK, NP.
The manuscript was reviewed and approved by all authors
except Professor Ulrich Vogel. He had a major contribution to theconcept and design of the study as well as in obtaining funding. As
he passed away on the 4th of October 2022 during manuscript
drafting, he was not able to review and approve the ﬁnal version of194€user, A. Gabel et al.
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