By Kate Kelland
LONDON (Reuters) – Almost everyone previously infected with COVID-19 has high levels of antibodies for at least six months that are likely to protect them from reinfection with the disease, the results of a large study in the UK showed on Wednesday.
The scientists said the study, which measured levels of previous COVID-19 infection in populations in Britain, as well as how long antibodies persisted in infected people, should provide some guarantee that rapid cases of reinfection will be rare.
“The vast majority of people retain detectable antibodies for at least six months after infection with the coronavirus,” said Naomi Allen, professor and chief scientist at UK Biobank, where the study was conducted.
Among participants who tested positive for previous COVID-19 infection, 99% retained antibodies to SARS-CoV-2 for three months, the results showed. After the full six months of follow-up in the study, 88% still had them.
“Although we cannot be sure how it relates to immunity, the results suggest that people can be protected against subsequent infections for at least six months after the natural infection,” said Allen.
She said the findings are also consistent with the results of other studies in the UK and Iceland, which found that antibodies to the coronavirus tend to persist for several months in people who have already had the disease and recover.
A study of UK health professionals published last month found that people who had COVID-19 are likely to be protected for at least five months, but noted that those with antibodies may still be able to carry and spread the virus.
The UK Biobank study also found that the proportion of the UK population with COVID-19 antibodies – a measure known as seroprevalence – increased from 6.6% at the beginning of the study period in May / June 2020 to 8.8% in November / December 2020.
SARS-CoV-2 seroprevalence was more common in London, with 12.4%, and less common in Scotland with 5.5%, he found.
(Reporting by Kate Kelland; Editing by Alison Williams)
Originally published