London: People with Covid-19 are unlikely to catch it again for at least six months after the first infection, according to a British study of healthcare professionals on the front lines of fighting the coronavirus pandemic.
Researchers at the University of Oxford said that the results should provide some reassurance to the more than 51 million people worldwide who have contracted this epidemic disease.
“This is really good news, because we are confident that most people who catch Covid-19 will not catch it again in the short term at least,” said David Ayer, a professor in the Nuffield division of Population Health in Oxford who co-led the study.
Isolated cases of re-infection with Covid-19, the disease caused by the SARS-CoV-2 virus, have raised concerns that immunity may be short-lived and that recovered patients may quickly become ill again.
But the results of this study, conducted on a group of UK healthcare workers – who are among the most at risk of contracting Covid-19 – indicate that cases of infection are likely to remain extremely rare.
“Being infected with Covid-19 provides protection from re-infection for most people for at least six months,” Ayer said. “We did not find any infection with new symptoms in any of the participants who had tested positive for antibodies.
The study, part of a large employee testing program, covered a 30-week period between April and November 2020. Its results were not reviewed by other scientists, but were published prior to the review on the MedRxiv website.
During the study, 89 of 11,052 employees who had no antibodies developed a new infection with symptoms, while none of the 1,246 employees who had antibodies developed asymptomatic infection.
The researchers said employees who had antibodies were less likely to test positive for Covid-19 without symptoms, with 76 without testing positive for the antibodies, compared to only three with the antibodies. They added that these three were in good health and had no symptoms of COVID-19.
“We will continue to carefully follow this group of employees to see how long protection lasts and whether previous infections affect the severity of the infection if people are infected again,” Ayer said.