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COVID-19 reinfection unlikely for at least six months after recovery, study finds

Prior COVID-19 infection may offer at least six months of immunity against the virus, a new study suggests. File Photo by Jim Ruymen/UPI
Prior COVID-19 infection may offer at least six months of immunity against the virus, a new study suggests. File Photo by Jim Ruymen/UPI | License Photo

Nov. 20 (UPI) -- People who had COVID-19 are protected against reinfection with the virus for at least six months, according to a study posted online Friday by researchers at Oxford University in England.

"Being infected with COVID-19 does offer protection against reinfection for most people for at least six months ... [and] this is really good news, because we can be confident that, at least in the short term, most people who get COVID-19 won't get it again," study co-author David Eyre said in a press release.

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"We know from a previous study that antibody levels fall over time, but this latest study shows that there is some immunity in those who have been infected," said Eyre, a professor in Oxford's Nuffield Department of Population Health.

For this study, which has not yet been published in a medical journal and has not been peer-reviewed, Eyre and his colleagues performed repeated antibody testing on 12,180 healthcare workers at Oxford University Hospitals between April and November.

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By November, 1,246 of the study participants had developed antibodies against the new coronavirus while the remainder had not, according to the researchers.

The analysis found that none with antibodies against the virus tested positive over the course of roughly seven months.

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However, 89 of the more than 11,000 hospital staff members who did not have antibodies -- proteins produced by the human immune system to fight off infection -- contracted the virus during the study period.

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In addition, 76 staff members without antibodies tested positive for COVID-19, but did not have outward symptoms of the disease, while three of those with antibodies remained asymptomatic, according to the researchers.

The three healthcare workers with antibodies who tested positive for the virus that causes COVID-19 were all well and did not develop symptoms of the disease again, the researchers said.

To date, studies have found that antibodies against the new coronavirus offer varying levels of immunity from infection.

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Some researchers have found that immunity lasts up to seven months, while others have suggested the time period may be only 90 days in some people.

Several cases of reinfection have been reported, in which people with confirmed COVID-19 recover and then test positive -- with a different strain of the virus -- a few months later.

All of these studies on immunity and reinfection have implications as researchers seek to develop a vaccine against the virus and, hopefully, bring about an end to the pandemic.

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"We will continue to follow this cohort of staff carefully to see how long protection lasts and whether previous infection affects the severity of infection if people do get infected again," Eyre said.

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