Thursday 14 January 2021 12:01 am

Covid immunity 'lasts five months' but may not prevent transmission

People infected with Covid-19 are likely to be naturally protected against reinfection for around five months, according to the first government-funded study on the issue.

The first report from Public Health England’s (PHE) Siren study found that antibodies from past coronavirus infection lasted an average of at least five months.

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However, scientists warned that those with immunity may still be able to carry the virus and risk spreading it to others.

Experts detected 44 potential reinfections out of 6,614 participants with antibodies between 18 June and 24 November. That means people who have previously caught the virus will likely carry an 83 per cent rate of protection from reinfection.

PHE added that early evidence from the next stage of trials showed that some individuals continued to carry high levels of the virus, meaning they were likely to still transmit Covid to others despite holding antibodies.

“This study has given us the clearest picture to date of the nature of antibody protection against Covid-19 but it is critical people do not misunderstand these early findings,” said Professor Susan Hopkins, PHE’s senior medical advisor who oversaw the study.

“We now know that most of those who have had the virus, and developed antibodies, are protected  from reinfection, but this is not total and we do not yet know how long protection lasts. Crucially, we believe people may still be able to pass the virus on,” she added.

“This means even if you believe you already had the disease and are protected, you can be reassured it is highly unlikely you will develop severe infections but there is still a risk that you could acquire an infection and transmit to others. Now more than ever it is vital we all stay at home to protect our health service and save lives.”

The data is entirely separate to the likelihood of developing immunity against coronavirus from vaccines.

The Pfizer/Biontech vaccine is estimated to be 95 per cent effective in immunising against coronavirus, while data from trials of the Astrazeneca vaccine showed it was 90 per cent effective when administered in two doses.

The PHE study will continue to follow participants for 12 months to explore how long any immunity may last, the effectiveness of vaccines and to what extent people with immunity are able to carry and transmit the virus.

Ministers have pledged to vaccinate almost 14m of the UK’s most vulnerable population by mid-February, as the country grapples with its worst wave of coronavirus since the start of the pandemic.

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Vaccines tsar Nadhim Zahawi the morning said he was “absolutely” confident the government would meet its target, with more than 2.4m people vaccinated so far.

The UK today reported its highest ever daily Covid death rate, with a further 1,564 coronavirus-related deaths reported in the past 24 hours.

The number exceeds the previous record of 1,325 deaths last Friday, and means more people have now died in the second wave than in the first.