National and regional prevalence of SARS-CoV-2 antibodies in primary and secondary school children in England: the School Infection Survey, a national open cohort study, November 2021 (preprint)

Background Risk factors for infection and, therefore, antibody positivity rates will be different in children compared to adults. We aim to estimate national and regional prevalence of SARS-CoV-2 antibodies in primary (4-11-year-olds) and secondary (11-15-year-olds) school children between 10 November and 10 December 2021. Methods Cross-sectional surveillance in England using two stage sampling, firstly stratifying into regions and selecting local authorities, then selecting schools according to a stratified sample within selected local authorities. Participants were sampled using a novel oral fluid validated assay for SARS-CoV-2 spike and nucleocapsid IgG antibodies. Results 4,980 students from 117 state-funded schools (2,706 from 83 primary schools, 2,274 from 34 secondary schools) provided a valid sample. After weighting for age, sex and ethnicity, and adjusting for assay accuracy, the national prevalence of SARS-CoV-2 antibodies in primary school students, who were all unvaccinated, was 40.1% (95%CI; 37.3-43.0). Antibody prevalence increased with age (p<0.001) and were higher in urban than rural schools (p=0.01). In secondary school students, the adjusted, weighted national prevalence of SARS-CoV-2 antibodies was 82.4% (95%CI; 79.5-85.1); including 57.5% (95%CI; 53.9-61.1) in unvaccinated and 97.5% (95%CI; 96.1-98.5) in vaccinated students. Antibody prevalence increased with age (p<0.001), and was not significantly different in urban versus rural students (p=0.1). Conclusions Using a validated oral fluid assay, we estimated national and regional seroprevalence of SARS-CoV-2 antibodies in primary and secondary school students. In November 2021, 40% of primary school students and nearly all secondary school students in England had SARS-CoV2 antibodies through a combination of natural infection and vaccination.

A cross-sectional national investigation of COVID-19 outbreaks in nurseries during rapid spread of the Alpha (B.1.1.7) variant of SARS- CoV-2 in England (preprint)

Background: In England, the emergence the more transmissible SARS-CoV-2 variant Alpha (B.1.1.7) led to a third national lockdown from December 2020, including restricted attendance at schools. Nurseries, however, remained fully open. COVID-19 outbreaks (≥ 2 laboratory-confirmed cases within 14 days) in nurseries and assess the risk of SARS-CoV-2 infection and incidence rates in staff and children over a three-month period when community SARS-CoV-2 infections rates were high and the Alpha variant was spreading rapidly across England. Methods This was a cross-sectional national investigation of COVID-19 outbreaks in nurseries across England Nurseries reporting a COVID-19 outbreak to PHE between November 2020 and January 2021 were requested to complete a questionnaire about their outbreak. Results 324 nurseries, comprising 1% (324/32,852) of nurseries in England, reported a COVID-19 outbreak. Of the 315 (97%) nurseries contacted, 173 (55%) reported 1,657 SARS-CoV-2 cases, including 510 (31%) children and 1,147 (69%) staff. A child was the index case in 45 outbreaks (26%) and staff in 125 (72%) outbreaks. Overall, children had an incidence rate of 3.50% (95%CI, 3.21–3.81%) and was similar irrespective of whether the index case was a child (3.55%; 95%CI, 3.01–4.19%) or staff (3.44%; 95%CI, 3.10–3.82%). Among staff, incidence rates were lower if the index case was a child (26.28%; 95%CI, 23.54–29.21%%) compared to a staff member (32.98%; 95%CI, 31.19–34.82%), with the highest incidence rate when the index case was also a staff member (37.52%; 95%CI, 35.39–39.70%). Compared to November 2020, outbreak sizes and incidence rates were higher in January 2021, when the Alpha variant predominated. Nationally, SARS-CoV-2 infection rates in

Secondary Attack Rates in Primary and Secondary School Bubbles Following a Confirmed Case: Active, Prospective National Surveillance, November to December 2020, England (preprint)

Background: Following the full re-opening of schools in England and emergence of the SARS-CoV-2 Alpha variant, we investigated the risk of SARS-CoV-2 infection in students and staff who were contacts of a confirmed case in a school bubble (school groupings with limited interactions), along with their household members. Methods: Primary and secondary school bubbles were recruited into sKIDsBUBBLE after being sent home to self-isolate following a confirmed case of COVID-19 in the bubble. Bubble participants and their household members were sent home-testing kits comprising nasal swabs for RT-PCR testing and whole genome sequencing, and oral fluid swabs for SARS-CoV-2 antibodies. Results: During November-December 2020, 14 bubbles were recruited from 7 schools, including 269 bubble contacts (248 students, 21 staff) and 823 household contacts (524 adults, 299 children). The secondary attack rate was 10.0% (6/60) in primary and 3.9% (4/102) in secondary school students, compared to 6.3% (1/16) and 0% (0/1) among staff, respectively. The incidence rate for household contacts of primary school students was 6.6% (12/183) and 3.7% (1/27) for household contacts of primary school staff. In secondary schools, this was 3.5% (11/317) and 0% (0/1), respectively. Household contacts were more likely to test positive if their bubble contact tested positive although there were new infections among household contacts of uninfected bubble contacts. Interpretation: Compared to other institutional settings, the overall risk of secondary infection in school bubbles and their household contacts was low. Our findings are important for developing evidence-based infection prevention guidelines for educational settings.

Perceptions of Adolescents on the COVID-19 Pandemic and Returning to School: Qualitative Questionnaire Survey, England 2020 (preprint)

Background : Little is known about the views of adolescents returning to secondary school during the current COVID-19 pandemic. Methods: In September 2020, Public Health England (PHE) recruited staff and students in secondary schools to provide nasal swabs, oral fluid and blood samples for SARS-CoV-2 infection and antibody testing. Students aged 11-18 years in five London schools completed a short questionnaire about their perception of the pandemic, returning to school, risk to themselves and to others and infection control measures, and participating in school testing. Results: A questionnaire was completed by 64% (297/462) participants. Students were generally not anxious at all (19.7%; 58/294) or not really anxious (40.0%, 114/295) about returning to school, although 5.4% (n=16/295) were extremely nervous. Most students were very worried about transmitting the virus to their family (60.2%; 177/294) rather than other students (22.0%; 65/296) or school staff (19.3%; 57/296), or catching the infection themselves (12.5%; 37/296). Students better maintained physical distancing in the presence of school staff (84.6%; 247/292) and in public places (79.5%; 233/293) but not when with other students (46.8%; 137/293) or friends (40.8%; 120/294). A greater proportion of younger students (school years 7-9) reported not being anxious at all than 16-18 year olds (47/174 [27.0%] vs 3/63 [4.8%]; p=0.001). They were also less likely to adhere to physical distancing and wearing face masks. Most students reported positive experiences with testing in schools, with 92.3% (262/284) agreeing to have another blood test in future visits.Conclusions: Younger students were less concerned about catching and transmitting SARS-CoV-2 and were less likely to adhere to protective measures. Greater awareness of the potential risks of COVID-19 transmission between secondary school students potentially leading to increased risk of infection in their teachers and their household members may increase adherence to infection control measures within and outside schools.

Real World Data Demonstrating Increased Reactogenicity in Adults Receiving Heterologous Compared to Homologous Prime-Boost COVID-19 Vaccination: March-May 2021, England (preprint)

Adults receiving heterologous prime-boost COVID-19 immunisation schedules with mRNA (Pfizer-BioNTech) or adenoviral-vector (ChAdOx1-S/nCOV-19) vaccines had higher reactogenicity rates and were more likely to seek medical attention after their second dose than homologous schedules. Reactogenicity rates were generally higher among ≤50 than >50 year-olds and in adults with prior symptomatic or confirmed COVID-19. Adults receiving heterologous schedules because of severe first-dose reactions had lower reactogenicity after the second dose following ChAdOx1-S/Pfizer-BioNTech (93.4%[90.5-98.1] vs. 48%[41.0-57.7]) but not Pfizer-BioNTech/ChAdOx1-S (91.7%[77.5-98.2] vs. 75.0%[57.8-87.9]).

Implementation of COVID-19 Preventive Measures in Primary and Secondary Schools Following Reopening of Schools in Autumn 2020; A Cross-Sectional Study of Parents' and Teachers' Experiences in England (preprint)

Objective The main objective was to assess implementation of and ease of implementation of control measures in schools as reported by staff and parents. Design Cross-sectional study. Setting Staff and parents/guardian participants in the 132 primary schools and 20 secondary schools participating in sKIDs and sKIDsPLUS surveillances. Main outcome measure Prevalence of control measures implemented in Autumn 2020, parental and staff perception of ease of implementation and acceptability of conducting school surveillance studies. Results In total, 56/152 (37%) schools participating in Public Health England's sKIDs study of COVID in schools accepted the invitation to participate in the survey. By 28 December 2020, 1,953 parent and 986 staff respondents had completed the online questionnaire. While more than half the parents were positive about their children returning to school, roughly a third reported being a little anxious. 90% and 82% of primary and secondary school parents were either completely or partly reassured by the preventive measures implemented in their schools. Among staff, 80% of primary staff and 87% of secondary school staff felt that they were at higher risk of COVID-19 because of their profession; only 52% of primary school staff and 38% of secondary school staff reportedly felt safe. According to the teaching staff, most preventive measures were well-implemented apart from requiring 2-metre distancing between staff. For students, maintaining the 2-metre distance was reported to be particularly difficult. By extension, secondary schools also struggled to maintain small groups at all times or ensuring that the same staff were assigned to each student group (a problem also commonly reported by parents). Conclusions Variable implementation of infection control measures was reported by staff and parents. Whilst the majority were not worried about returning to school, some parents and staff, were concerned about returning to school and the risks posed to children, staff and household members.

COVID-19 Outbreaks in Nurseries During Rapid Spread of the B.1.1.7 Variant of SARS-CoV-2 in England: Cross-Sectional National Surveillance, November 2020 – January 2021 (preprint)

Background: The reopening of schools during the COVID-19 pandemic has raised concerns about widespread infection and transmission of SARS-CoV-2 in educational settings. In June 2020, Public Health England (PHE) initiated prospective national surveillance of SARS-CoV-2 in primary schools across England (sKIDs). We used this opportunity to assess the feasibility and agreeability of large-scale surveillance and testing for SARS-CoV-2 infections in school among staff, parents and students.Methods: Staff and students in 131 primary schools were asked to complete a questionnaire at recruitment and provide weekly nasal swabs for SARS-CoV-2 RT-PCR testing (n=86) or swabs with blood samples for antibody testing (n=45) at the beginning and end the summer half-term. In six blood sampling schools, students were asked to complete a pictorial questionnaire before and after their investigations.Results: In total, 134 children aged 4-7 years (n=40) or 8-11 years (n=95) completed the pictorial questionnaire fully or partially. Prior to sampling, oral fluid sampling was the most acceptable test (107/132, 81%) followed by throat swabs (80/134, 59%), nose swabs (77/132, 58%), and blood tests (48/130, 37%). Younger students were more nervous about all tests than older students but, after completing their tests, most children reported a “better than expected” experience with all the investigations. Students were more likely to agree to additional testing for nose swabs (93/113, 82%) and oral fluid (93/114, 82%), followed by throat swabs (85/113, 75%) and blood tests (72/108, 67%). Parents (n=3,994) and staff (n=2,580) selected a preference for weekly testing with nose swabs, throat swabs or oral fluid sampling, although staff were more flexible about testing frequency. Conclusions: Primary school staff and parents were supportive of regular tests for SARS-CoV-2 and selected a preference for weekly testing. Children preferred nose swabs and oral fluids over throat swabs or blood sampling.Funding Statement: This surveillance was internally funded by PHE and did not receive any specific grant funding from agencies in the public, commercial or not-for-profit sectors.Declaration of Interests: None.Ethics Approval Statement: PHE has legal permission, provided by Regulation 3 of The Health Service (Control of Patient Information) Regulations 2002, to process patient confidential information for national surveillance of communicable diseases and as such, individual patient consent is not required.

COVID-19 Outbreaks Following Full Reopening of Primary and Secondary Schools in England: Retrospective, Cross-Sectional National Surveillance (preprint)

Background: The full reopening of schools in September 2020 was associated with an increase in COVID-19 cases and outbreaks in educational settings across England. Methods: Primary and secondary schools reporting an outbreak (≥2 laboratory-confirmed cases within 14 days) to Public Health England (PHE) between 31 August and 18 October 2020 were contacted to complete an online questionnaire. Interpretation: There were 969 primary (n=450) and secondary school outbreaks (n=519) reported to PHE, representing 3% of primary schools and 15% of secondary schools in England. Of the 369 schools contacted, 190 geographically-representative schools completed the questionnaire; 2,425 cases were reported. Secondary school students (1.20%; 95%CI, 1.13-1.28%) had higher attack rates than primary school students (0.84%; 95%CI, 0.75-0.94%). Outbreaks were larger and across more year groups in secondary schools than in primary schools. When an outbreak occurred, attack rates were higher in staff (926/19,083; 4.85%; 95%CI, 4.55-5.17%) than students, especially among primary school teaching staff (9.81%; 95%CI, 8.90-10.82%) compared to secondary school teaching staff (3.97%; 95%CI, 3.79-5.69%). Staff represented 59% (471/799) of cases in primary school outbreaks and 27% (410/1515) in secondary schools (P<0.001). Teaching staff were more likely to be the index case in primary (48/100, 48%) than in secondary (25/79, 32%) schools (P=0.027).Conclusions: Secondary schools were more likely to be affected by a COVID-19 outbreak than primary schools and to experience larger outbreaks across multiple school years. The higher attack rate among teaching staff during an outbreak suggests that additional protective measures may be needed. Funding: PHE

COVID-19 Outbreaks Following Full Reopening of Primary and Secondary Schools in England: Retrospective, Cross-Sectional National Surveillance (preprint)

Background: The full reopening of schools in September 2020 was associated with an increase in COVID-19 cases and outbreaks in educational settings across England.Methods: Primary and secondary schools reporting an outbreak (≥2 laboratory-confirmed cases within 14 days) to Public Health England (PHE) between 31 August and 18 October 2020 were contacted to complete an online questionnaire.Interpretation: There were 969 primary (n=450) and secondary school outbreaks (n=519) reported to PHE, representing 3% of primary schools and 15% of secondary schools in England. Of the 369 schools contacted, 190 geographically-representative schools completed the questionnaire; 2,425 cases were reported. Secondary school students (1.20%; 95%CI, 1.13-1.28%) had higher attack rates than primary school students (0.84%; 95%CI, 0.75-0.94%). Outbreaks were larger and across more year groups in secondary schools than in primary schools. When an outbreak occurred, attack rates were higher in staff (926/19,083; 4.85%; 95%CI, 4.55-5.17%) than students, especially among primary school teaching staff (378/3852; 9.81%; 95%CI, 8.90-10.82%) compared to secondary school teaching staff (284/7146; 3.97%; 95%CI, 3.79-5.69%). Staff represented 59% (471/799) of cases in primary school outbreaks and 27% (410/1515) in secondary schools (P<0.001). Teaching staff were more likely to be the index case in primary (48/100, 48%) than in secondary (25/79, 32%) schools (P=0.027). Conclusions: Secondary schools were more likely to be affected by a COVID-19 outbreak than primary schools and to experience larger outbreaks across multiple school years. The higher attack rate among teaching staff during an outbreak suggests that additional protective measures may be needed.Funding Statement: This surveillance was internally funded by PHE and did not receive any specific grant funding from agencies in the public, commercial or not-for-profit sectors.Declaration of Interests: The authors declare no conflicts of interest.Ethics Approval Statement: PHE has legal permission, provided by Regulation 3 of The Health Service (Control of Patient Information) Regulations 2002, to process patient confidential information for national surveillance of communicable diseases and as such, individual patient consent is not required.