ABSTRACT
The duration of immunity after first SARS-CoV-2 infection and the extent to which prior immunity prevents reinfection is uncertain and remains an important question within the context of new variants. Using a retrospective population-based matched observational study approach, we identified cases with a first PCR positive test between 01 March 2020 and 30 September 2020 and cases were matched by age, sex, upper tier local authority of residence and testing route to individuals testing negative in the same week (controls) by PCR. After a 90-day pre-follow up period for cases and controls, any subsequent positive tests up to 31 December 2020 and deaths within 28 days of testing positive were identified, this encompassed an essentially vaccine-free period. There were 517,870 individuals in the matched cohort with 2,815 reinfection cases and 12,098 first infections. The protective effect of a prior SARS-CoV-2 PCR-positive episode was 78% (OR 0.22, 0.21-0.23). Protection rose to 82% (OR 0.18, 0.17-0.19) after a sensitivity analysis excluded 934 individuals with a first test between March and May and a subsequent positive test between June and September 2020. Amongst individuals testing positive by PCR during follow-up, reinfection cases had 77% lower odds of symptoms at the second episode (adjusted OR 0.23, 0.20-0.26) and 45% lower odds of dying in the 28 days after reinfection (adjusted OR 0.55, 0.42-0.71). Prior SARS-CoV-2 infection offered protection against reinfection in this population. There was some evidence that reinfections increased with the Alpha variant compared to the wild-type SARS-CoV-2 variant highlighting the importance of continued monitoring as new variants emerge.
Subject(s)
COVID-19ABSTRACT
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
Subject(s)
COVID-19ABSTRACT
Background: The reopening of schools during the COVID-19 pandemic has raised concern for the safety of staff and students, their families and the wider community. We monitored SARS-CoV-2 infection rates in school-aged children and compared them with adult infection rates before and after schools reopened in England. Methods: Public Health England receives daily electronic reports of all SARS-CoV-2 tests nationally. SARS-CoV-2 infection rates by school year from July to November 2020 were analysed, including the effect of a week-long half-term school break in October and national month-long lockdown whilst keeping schools open in November 2020Findings: SARS-CoV-2 infections rates were low during early summer but started increasing in mid-August, initially in young adults followed by secondary and then primary school-aged children prior to schools reopening in September 2020. Cases in school-aged children lagged behind and followed adult trends after schools reopened, with a strong age gradient in weekly infection rates. There was a strong (P<0.001) correlation in regional infection rates between adults and secondary (R2=0.96-0.98), primary (R2=0.93-0.94) and preschool-aged (R2=0.62-0.85) children. The half-term break had a small and transient effect on infection rates in school-aged children, but there was a sharp decline in adult cases followed a week later by a decline in student cases after national lockdown in November 2020.Interpretation: In school-aged children, SARS-CoV-2 infections followed the same trajectory as adult cases and only declined after national lockdown was implemented whilst keeping schools open. Maintaining low community infection rates is critical for keeping schools open during the pandemic.Funding: PHE
Subject(s)
COVID-19ABSTRACT
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.