Recovered Covid patients protected from infection for at least six months, study says

Research provides reassurance that fast reinfection will be rare

A woman wearing a mask against coronavirus walks past a neon sign display at the Wellcome Institute in London. AP

Almost all people infected with Covid-19 have a high level of antibodies for at least six months, which is likely to protect them from reinfection, a major UK study showed on Wednesday.

The study, which measured levels of those across Britain who were earlier infected with Covid-19 and how long antibodies persisted, should provide some reassurance that cases of fast reinfection will be rare.

Among participants who previously tested positive for Covid-19, 99 per cent retained antibodies to battle the coronavirus for three months, the results showed.

After the full six months of follow-up in the study, 88 per cent still had them.

"Although we cannot be certain how this relates to immunity, the results suggest that people may be protected against subsequent infection for at least six months after natural infection," said Prof Naomi Allen, chief scientist at the UK Biobank, where the study was carried out.

Prof Allen said the findings were consistent with results of other studies in the UK and Iceland, which found antibodies to the coronavirus tended to persist for months in those who have recovered.

A study of UK healthcare workers published last month found that people who had Covid-19 were likely to be protected for at least five months, but said those with antibodies might still be able to carry and spread the virus.

The UK Biobank study found that the proportion of British people with Covid-19 antibodies – a measure known as seroprevalence – rose from 6.6 per cent at the start of the study in May-June 2020 to 8.8 per cent by November-December.

The study found seroprevalence was most common in London, at 12.4 per cent, and least common in Scotland at 5.5 per cent.