LONDON (Reuters) – Nearly all people previously infected with COVID-19 have elevated levels of antibodies for at least six months that will likely protect them from reinfection with the disease, the results of a major UK study showed on Wednesday.
The scientists said the study, which measured levels of previous COVID-19 infection in UK populations, as well as how long antibodies persisted in those infected, should provide some certainty that rapid cases of COVID-19 reinfection will be uncommon.
“The vast majority of people retain detectable antibodies for at least six months after coronavirus infection,” said Naomi Allen, a professor and chief scientist at the UK Biobank, where the study was conducted.
Among participants who had tested positive for previous COVID-19 infection, 99% retained antibodies to SARS-CoV-2 for three months, according to the results. After the full six months of follow-up of the study, 88% still had it.
“While we can’t be sure how this relates to immunity, the results suggest that people may be protected from later infection for at least six months after the natural infection,” Allen said.
He said the findings were also consistent with the results of other studies in the UK and Iceland, which found that antibodies to coronavirus used to persist for several months in those who have had the disease and have recovered.
A UK health worker study published last month found that people who have had COVID-19 would likely be protected for at least five months, but noted that people with antibodies could still 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 by 6.6% at the start of the study period in May / June 2020 at 8.8% in November / December 2020.
The seroprevalence of SARS-CoV-2 was the most common in London, at 12.4%, and the least common in Scotland at 5.5%.
Reports by Kate Kelland; Edited by Alison Williams