Virus immunity unlikely to be permanent

Both worldwide and locally, evidence is mounting that it’s possible to contract COVID-19 more than once, putting a serious damper on hopes that herd immunity could one day bring an end to the pandemic. As with other types of coronavirus, it appears that a person’s immunity will only last so long.

The Laramie Boomerang reported on Thursday that an Albany County resident had tested positive for the second time, around six months after first testing positive in March. Amy Surdam, chief operating officer for Stitches Acute Care Center, told the Boomerang: “There are lots of known reinfections occurring in the nation. And I think the bigger point is that antibodies wane after a period of time — we’re thinking about four months or so.”

This matches with reports from South Dakota, where state epidemiologist Joshua Clayton has announced 28 possible reinfections across the state: situations in which individuals tested positive a second time at least 90 days after their initial infection. However, Clayton on Wednesday cautioned that these reinfections have not yet been confirmed by the Centers for Disease Control (CDC).

The news from this region comes two weeks after a study was released in a journal called Lancet Infectious Diseases that revealed a 25-year-old man from Nevada had caught COVID-19 twice in a period of less than three months, with the second infection far more dangerous than the first. He did not have known health issues or conditions that would make him vulnerable to the virus.

Meanwhile, in Britain, tests on more than 365,000 via Imperial College London showed that the number of people who tested positive for antibodies against the disease dropped by 26.5% between mid-June and mid-September. Antibodies do not represent the body’s full immune response to a disease but are believed to play an important part.

“This very large study has shown that the proportion of people with detectable antibodies is falling over time,” said Professor Helen Ward, one of the lead authors of the report.

“We don’t yet know whether this will leave these people at risk of reinfection with the virus that causes COVID-19, but it is essential that everyone continues to follow guidance to reduce the risk to themselves and others.”

The news that reinfection may be possible is not necessarily a surprise. Only a few viruses, such as the one that causes measles, will cause a patient to create antibodies that last for virtually a lifetime.

The CDC has not yet released official guidance on the likelihood of reinfection. At this time, its official stance is that “confirmed and suspected cases of reinfection of the virus that causes COVID-19 have been reported, but remain rare.”

According to the CDC, studies are ongoing to find out more about the likelihood of reinfection, how quickly it can occur after a first bout of the disease, how severe cases of reinfection will typically be and who might be at risk.