Elliott1, Maya Moshe2, Jonathan C Brown2, Barney Flower2,4, Anna Daunt2,4, Kylie
Ainslie1,5, Deborah Ashby1, Christl Donnelly1,6, Steven Riley1,5, Ara Darzi3,4, Wendy
Barclay2,†, Paul Elliott1,4,7,8,9† for the REACT study team
Abstract
Background
The prevalence and persistence of antibodies following a peak SARS-CoV-2 infection
provides insights into its spread in the community, the likelihood of reinfection and potential
for some level of population immunity.
The prevalence and persistence of antibodies following a peak SARS-CoV-2 infection
provides insights into its spread in the community, the likelihood of reinfection and potential
for some level of population immunity.
Methods
Prevalence of antibody positivity in England, UK (REACT2) with three cross-sectional
surveys between late June and September 2020. 365104 adults used a self-administered
lateral flow immunoassay (LFIA) test for IgG. A laboratory comparison of LFIA results to
neutralization activity in panel of sera was performed.
Prevalence of antibody positivity in England, UK (REACT2) with three cross-sectional
surveys between late June and September 2020. 365104 adults used a self-administered
lateral flow immunoassay (LFIA) test for IgG. A laboratory comparison of LFIA results to
neutralization activity in panel of sera was performed.
Results
There were 17,576 positive tests over the three rounds. Antibody prevalence, adjusted for test
characteristics and weighted to the adult population of England, declined from 6.0% [5.8,
6.1], to 4.8% [4.7, 5.0] and 4.4% [4.3, 4.5], a fall of 26.5% [-29.0, -23.8] over the three
months of the study. There was a decline between rounds 1 and 3 in all age groups, with the
highest prevalence of a positive result and smallest overall decline in positivity in the
youngest age group (18-24 years: -14.9% [-21.6, -8.1]), and lowest prevalence and largest
decline in the oldest group (75+ years: -39.0% [-50.8, -27.2]); there was no change in
antibody positivity between rounds 1 and 3 in healthcare workers (+3.45% [-5.7, +12.7]).
The decline from rounds 1 to 3 was largest in those who did not report a history of COVID
19, (-64.0% [-75.6, -52.3]), compared to -22.3% ([-27.0, -17.7]) in those with SARS-CoV-2
infection confirmed on PCR.
There were 17,576 positive tests over the three rounds. Antibody prevalence, adjusted for test
characteristics and weighted to the adult population of England, declined from 6.0% [5.8,
6.1], to 4.8% [4.7, 5.0] and 4.4% [4.3, 4.5], a fall of 26.5% [-29.0, -23.8] over the three
months of the study. There was a decline between rounds 1 and 3 in all age groups, with the
highest prevalence of a positive result and smallest overall decline in positivity in the
youngest age group (18-24 years: -14.9% [-21.6, -8.1]), and lowest prevalence and largest
decline in the oldest group (75+ years: -39.0% [-50.8, -27.2]); there was no change in
antibody positivity between rounds 1 and 3 in healthcare workers (+3.45% [-5.7, +12.7]).
The decline from rounds 1 to 3 was largest in those who did not report a history of COVID
19, (-64.0% [-75.6, -52.3]), compared to -22.3% ([-27.0, -17.7]) in those with SARS-CoV-2
infection confirmed on PCR.
Discussion
These findings provide evidence of variable waning in antibody positivity over time such
that, at the start of the second wave of infection in England, only 4.4% of adults had
detectable IgG antibodies using an LFIA. Antibody positivity was greater in those who
reported a positive PCR and lower in older people and those with asymptomatic infection.
These data suggest the possibility of decreasing population immunity and increasing risk of
reinfection as detectable antibodies decline in the population.
These findings provide evidence of variable waning in antibody positivity over time such
that, at the start of the second wave of infection in England, only 4.4% of adults had
detectable IgG antibodies using an LFIA. Antibody positivity was greater in those who
reported a positive PCR and lower in older people and those with asymptomatic infection.
These data suggest the possibility of decreasing population immunity and increasing risk of
reinfection as detectable antibodies decline in the population.
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