The online questionnaire asked respondents to categorize the 86 health service interventions as essential, highly suitable, suitable or unsuitable for inclusion within SHS and whether this was applicable everywhere or in certain geographic areas only. These questions were mandatory, meaning that respondents needed to answer each question on a page of 2-6 questions (even if only to select "Do not know") before moving on to the next page sequentially. Respondents also had the option to write in up to three additional interventions that they believed were essential to include in SHS, again with qualification of whether each should be included everywhere or in certain geographic areas only. Finally, respondents were asked to answer seven optional questions about their sociodemographic background. The only multiple-choice questions in the questionnaire were some of these respondent sociodemographic questions, relating to nationality, geographic area of expertise, health area of expertise and profession.
The survey was designed to be closed and confidential. Each pre-selected expert was sent an email invitation with a unique link to the online questionnaire. Early drafts of the questionnaire were developed in English and administered by WHO using the programme LimeSurvey. The survey was pre-tested with WHO staff (n = 3) in April 2019 and then pilot-tested with SHS Guideline Steering Group members and Guideline Development Group (GDG) members at the May 2019 GDG meeting (n = 18). At the GDG meeting, participants reviewed the planned survey protocol, the draft questionnaire and the results of the pilot test and instructed WHO on revisions that should be made prior to finalization of the questionnaire.
At the May 2019 meeting, the GDG requested that, if feasible, the three main questionnaire sections (A. promotion, B. prevention and C. care and treatment) be randomly ordered so that respondents might receive any of six versions of the questionnaire (ABC, ACB, BAC, BCA, CAB, CBA).
The intention was to reduce the chance of bias related to answer order if, for instance, respondents only completed early questions fully, meaning all three sections would have an equal chance of full completion. However, at this meeting the GDG also requested WHO to administer the questionnaire in all six WHO languages. With the need for six different questionnaires to accommodate six languages, it became too difficult to also randomize sections, so section order randomization was not done.

# G.1.2 Selection of experts for the global survey on SHS
WHO employed multiple approaches to compile a list of email addresses of experts who would be invited to participate in the survey of expert opinion, including the following.
A search of journal article databases using the key term "school health", followed by review of the article lists to identify relevant titles and abstracts and then search for and inclusion of one author's email address per article.

# G.1.4 Quantitative and qualitative data analysis
For quantitative data analysis, a partial completion cut-off was established for inclusion within the final dataset. This cut-off was set at > 6% of the mandatory questions (the first page of questions or five of 86 mandatory intervention questions).
Of the 1293 experts who were emailed invitations to the survey, 442 (34%) completed at least the first page of five questions, of whom 417 (94%) completed all 86 mandatory questions. One hundred and eighty-eight respondents (44%) wrote at least one suggestion in response to the optional questions about additional essential interventions. In total there were 378 suggestions, approximately three fifths (63%) of which were in English and one fifth (22%) in French, followed by 7% Spanish, 6% Chinese, 2% Arabic and none in Russian.

# G.2 Select survey findings

# G.2.1 Respondent sociodemographic information
Survey respondents' ages ranged from 25 to 81 years, with a mean and median age of 51 years.
Respondents represented 81 nationalities, the 12 most common being: the Philippines (n = 56), United States of America (42), China (38), United Kingdom (26), Australia (18), Canada (13), India (13), South Africa (13), Tunisia (13), Germany (10), Jordan (9) and Sweden ( 9). Table G.1 details other self-reported sociodemographic characteristics of survey respondents.

# G.2.2 Interventions ranked as essential in SHS everywhere
Overall, the interventions that were ranked most highly by survey respondents as essential in SHS everywhere were in the general health areas of health promotion and health education. The top five specific interventions were: promotion of personal hygiene and handwashing with soap (80%); provision of sexual and reproductive health education (75%); promotion of health literacy (73%); health education about nutrition (73%); and promotion of oral health care (70%). However, five of the top seven interventions in this category were among the first six questions of the questionnaire, so the possibility of some bias in response patterns (such as an initially affirmative response to all questions, followed by more subtle distinctions in later responses) cannot be ruled out. To address this possibility, "Essential everywhere" rankings of clinical interventions were also examined separately.
Clinical interventions that were ranked most highly by survey respondents as essential in SHS everywhere were in the areas of immunization, screening, assessment and general care. The top five specific interventions were: administration of immunizations recommended for all children (68%); screening for vision problems (67%); provision of first aid (66%); screening for hearing problems (64%); and identification of developmental difficulties and disabilities (60%).

# G.2.3 Interventions ranked as essential in SHS in certain geographic areas only
The interventions that were ranked most highly by survey respondents as essential in SHS in certain geographic areas only address diverse conditions that have limited geographic range due to disease prevalence, population, resources, ecology and/ or climate. The interventions that were ranked most highly in this category were in the areas of immunization, mass drug administration and health promotion, followed by screening and referral for communicable and noncommunicable diseases. The top five specific interventions were: administration of immunizations recommended for children residing in certain regions (49%); provision and promotion of use of insecticide-treated bed nets (48%); administration of immunizations recommended for children in some high-risk populations (44%); mass drug administration (38%); and promotion of use of sunscreen to prevent sunburn and skin cancer (27%).

# G.2.4 Interventions ranked as unsuitable in SHS anywhere
The interventions that were ranked most highly by survey respondents as being UNSUITABLE IN SHS ANYWHERE mainly fell under the category of noncommunicable disease screening, although specific interventions from other health-care categories (general care, sexual and reproductive health preventive care, mental health, injury and immunization) also ranked highly. The top five specific interventions were: screening for hypertension (14%); administration of over-thecounter and prescribed medications (13%); and screening for diabetes (12%), scoliosis (12%) and other chronic conditions that may be undiagnosed (12%). Notably, the five interventions that were ranked most highly as "Unsuitable everywhere" were categorized in this way by only 12-14% of respondents and 2-3 times that proportion of respondents ranked each of these same interventions as "Essential everywhere" or "Essential in certain geographic areas only". Four fifths (81%) of the interventions in the questionnaire were only ranked "Unsuitable everywhere" by 0-4% of respondents.
There were no important differences in the results either by WHO region or by the profession of the respondent.

# G.2.5 Additional essential intervention suggestions

# G.3 Survey conclusions
The survey of expert opinion succeeded in collecting meaningful data on the suitability of potential SHS interventions from a large and diverse sample of experts. Responses to all of the interventions listed in the questionnaire generally were favourable and there were no interventions that received an overwhelmingly negative response. The high overall ranking of health promotion and education interventions as "Essential everywhere" indicates that these are considered to be very important roles for health workers to perform within a school setting. The clinical interventions that ranked most highly as "Essential everywhere" were in the areas of immunization and mass drug administration, screening, assessment and general care. Similarly, the most common write-in suggestions were in the areas of health education, other aspects of HPS and screening and care for noncommunicable conditions.