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. 2023 Oct 23:14:1186134.
doi: 10.3389/fimmu.2023.1186134. eCollection 2023.

Protection from infection and reinfection due to the Omicron BA.1 variant in care homes

Saher Choudhry #  1 , Thomas A J Rowland #  1 , Kamil McClelland #  1 , Erik Renz  1 , Nalini Iyanger  2 , J Yimmy Chow  2 , Felicity Aiano  3 , Shamez N Ladhani  3 , Anna Jeffery-Smith  1 , Nick J Andrews  4 , Maria Zambon  1
Affiliations

Protection from infection and reinfection due to the Omicron BA.1 variant in care homes

Saher Choudhry et al. Front Immunol. .

Abstract

Introduction: Following the emergence of SARS-CoV-2 in 2020, care homes were disproportionately impacted by high mortality and morbidity of vulnerable elderly residents. Non-pharmaceutical interventions (NPIs) and improved infection control measures together with vaccination campaigns have since improved outcomes of infection. We studied the utility of past infection status, recent vaccination and anti-S antibody titres as possible correlates of protection against a newly emergent Omicron variant infection.

Methods: Prospective longitudinal surveillance of nine sentinel London care homes from April 2020 onwards found that all experienced COVID-19 outbreaks due to Omicron (BA.1) during December 2021 and January 2022, despite extensive prior SARS-CoV-2 exposure and high COVID-19 vaccination rates, including booster vaccines (>70% residents, >40% staff).

Results: Detailed investigation showed that 46% (133/288) of Omicron BA.1 infections were SARS-CoV-2 reinfections. Two and three COVID-19 vaccine doses were protective against Omicron infection within 2-9 weeks of vaccination, though protection waned from 10 weeks post-vaccination. Prior infection provided additional protection in vaccinated individuals, approximately halving the risk of SARS-CoV-2 infection.

Discussion: Anti-S antibody titre showed a dose-dependent protective effect but did not fully account for the protection provided by vaccination or past infection, indicating that other mechanisms of protection are also involved.

Keywords: COVID-19; Omicron (BA1); SARS-CoV-2; care homes; correlate of protection; outbreaks; vaccine.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Infection status calculated for start of study period (1st December 2021). Vaccination dose for case defined as number of doses received 14 days prior to positive test result. Vaccination dose for non-cases defined as number of doses received 14 days prior to start of study period. Data for this figure was taken from Supplementary Table 2 .
Figure 2
Figure 2
Primary Infection or reinfection during study period stratified by age and role.
Figure 3
Figure 3
Distribution of Antibody titres.
See this image and copyright information in PMC

References

    1. Krutikov M, Stirrup O, Nacer-Laidi H, Azmi B, Fuller C, Tut G, et al. . Outcomes of SARS-CoV-2 Omicron infection in residents of long-term care facilities in England (VIVALDI): a prospective, cohort study. Lancet Healthy Longev (2022) 3(5):e347–55. doi: 10.1016/S2666-7568(22)00093-9 - DOI - PMC - PubMed
    1. Adult social care monthly statistics. England: GOV.UK; (2021). Available at: https://www.gov.uk/government/statistics/adult-social-care-in-england-mo....
    1. Weekly Flu and COVID-19 report week 1 2022.pdf . Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploa....
    1. UK Health Security Agency. SARS-CoV-2 variants of concern and variants under investigation in England: Technical briefing 35 (2022). Available at: htpps://assets.publishing.service.gov.uk/media/61f3c7388fa8f5388cafda99/Technica... (Accessed April 10, 2023).
    1. Jeffery-Smith A, Rowland TAJ, Patel M, Whitaker H, Iyanger N, Williams SV, et al. . Reinfection with new variants of SARS-CoV-2 after natural infection: a prospective observational cohort in 13 care homes in England. Lancet Healthy Longev (2021) 2(12):e811–9. doi: 10.1016/S2666-7568(21)00253-1 - DOI - PMC - PubMed

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