A University of Oxford study has found that people who contracted Covid-19 had antibodies for at least six months, meaning the chance of reinfection within that time frame is extremely unlikely.
The paper, released on Thursday, is yet to be peer-reviewed but was published on the MedRxiv website.
Part of collaboration between the University of Oxford and Oxford University Hospitals (OUH) NHS Foundation Trust, it is the first large scale study to investigate Covid-19 reinfection.
It monitored more than 12,000 healthcare workers employed at OUH and found that the chance of infection was hugely reduced in staff who had previously contracted Covid-19.
Of the 11,052 employees without Covid-19 antibodies, 89 developed an infection with symptoms during the 30-week period. Meanwhile, none of the 1,246 staff with antibodies developed a symptomatic infection.
The study also found that staff with antibodies were less likely to have an asymptomatic infection.
Only three staff members with antibodies tested positive for Covid-19 without symptoms. In the same period, 76 staff without antibodies tested positive but didn’t have any symptoms.
Lead investigators and authors of the study Katie Jeffery and David Eyre said the results were cause for cautious optimism, and the researchers will continue to monitor staff to see how long protection lasts.
Eyre, a professor at Oxford’s Nuffield Department of Population Health, said the study has “shown that being infected with Covid-19 does offer protection against reinfection for most people for at least six months.”
Jeffery, the director of Infection Prevention and Control for Oxford University Hospitals, described the results as an “exciting find” which indicates “at least short-term protection from reinfection.”
The prospect of the human body retaining some ability to ward off future Covid reinfections has been raised before.
Earlier in November, a small study carried out by Birmingham University found that while antibody levels dropped in patients during the months following their infection, the T-cell response – an important part of the immune system – remained robust.
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