Reinfection with new variants of SARS-CoV-2 after natural infection: a prospective observational cohort in 13 care homes in England

Abstract

Background Understanding the duration of protection and risk of reinfection after natural infection is crucial to planning COVID-19 vaccination for at-risk groups, including care home residents, particularly with the emergence of more transmissible variants. We report on the duration, neutralising activity, and protection against the alpha variant of previous SARS-CoV-2 infection in care home residents and staff infected more than 6 months previously. Methods We did this prospective observational cohort surveillance in 13 care homes in Greater London, England. All staff and residents were included. Staff and residents had regular nose and throat screening for SARS-CoV-2 by RT-PCR according to national guidelines, with ad hoc testing of symptomatic individuals. From January, 2021, antigen lateral flow devices were also used, but positive tests still required RT-PCR confirmation. Staff members took the swab samples for themselves and the residents. The primary outcome was SARS-CoV-2 RT-PCR positive primary infection or reinfection in previously infected individuals, as determined by previous serological testing and screening or diagnostic RT-PCR results. Poisson regression and Cox proportional hazards models were used to estimate protective effectiveness of previous exposure. SARS-CoV-2 spike, nucleoprotein, and neutralising antibodies were assessed at multiple timepoints as part of the longitudinal follow-up. Findings Between April 10 and Aug 3, 2020, we recruited and tested 1625 individuals (933 staff and 692 residents). 248 participants were lost to follow-up (123 staff and 125 residents) and 1377 participants were included in the follow-up period to Jan 31, 2021 (810 staff and 567 residents). There were 23 reinfections (ten confirmed, eight probable, five possible) in 656 previously infected individuals (366 staff and 290 residents), compared with 165 primary infections in 721 susceptible individuals (444 staff and 277 residents). Those with confirmed reinfections had no or low neutralising antibody concentration before reinfection, with boosting of titres after reinfection. Kinetics of binding and neutralising antibodies were similar in older residents and younger staff. Interpretation SARS-CoV-2 reinfections were rare in older residents and younger staff. Protection from SARS-CoV-2 was sustained for longer than 9 months, including against the alpha variant. Reinfection was associated with no or low neutralising antibody before reinfection, but significant boosting occurred on reinfection. Funding Public Health England.

Induction of SARS-CoV-2 neutralizing antibodies by CoronaVac and BNT162b2 vaccines in naïve and previously infected individuals

“…However, current evidence of re-infections with the same virus variant remains limited. 7 , 35 , 36 , 37 However this is a situation that continues to evolve given the emergence of VOCs such as Gamma, and Delta, which have shown significant reduction in cross-reactive neutralizing titre, and have generated increased rates of re-infection in some regions of the world, 38 , 39 , 40 a scenario that remains to be fully evaluated with the new VOC, Omicron. To further strengthen models for protective correlates, additional comparative analyses of nAb titres of vaccinated individuals and better-defined standards for convalescent sera that incorporate titre variations due to disease severity and decay over time are needed.…”

Persistence of Naturally Acquired and Functional SARS-CoV-2 Antibodies in Blood Donors One Year after Infection

“…[ 13 ]. Furthermore, there is an increasing number of reports concerning the reinfection of people previously infected with SARS-CoV-2 [ 14 , 15 , 16 ]. The actual numbers of SARS-CoV-2 infections are difficult to estimate due to asymptomatic or mild disease courses.…”

Changing dynamics of COVID-19 deaths during the SARS-CoV2 B.1.617.2 (Delta variant) outbreak in England and Wales: Reduced COVID-19 deaths among the Care Home residents

“…The reduced deaths rates in the Care Homes during the Delta variant surge are probably due to multiple interventions, first of which is the infection control and protective measures implemented in the Care Homes with the lessons learned from previous surges [9][10][11][12][13][14] . The greater adoption of COVID-19 vaccination among the Care Home residents and immunity from previous SARS-CoV2 infections are also potential contributary factors for reduced deaths during the Delta variant surge in Care Homes which need further study 17,[27][28][29] .…”