WHO warns Covid re-infections may occur as data suggests antibodies are declining

World Health Organization officials on Friday warned that, although sparse, recent data suggests that people who have already been infected with the coronavirus may become infected again as their antibody response wanes.

“We have seen the number of people infected continue to increase, but we are also seeing data emerging that protection may not last a lifetime, and as a result, we can see re-infections starting to occur,” Dr Mike Ryan , WHO’s executive director of health emergency program, said during a press briefing at the organization’s headquarters in Geneva. “So the question is: what are the levels of protection in society?”

According to the United States Centers for Disease Control and Prevention, a person was infected with the virus, recovered, and then infected again afterwards. Based on the CDC’s experience with other viruses, re-infections of Covid-19 are expected, the agency said.

However, researchers are trying to determine the likelihood and frequency of reinfection, among other considerations such as the severity of the reinfection and how quickly it can occur after the first infection.

Maria Van Kerkhove, head of the WHO’s Emerging Diseases and Zoonoses Unit, said researchers are still trying to determine how long an antibody response lasts after infection with the virus.

“What we understand is that 90-100% of people infected with the coronavirus develop an antibody response whether you have a mild infection, an asymptomatic infection up to a severe infection,” she said.

Ongoing research indicates that an immune response can last for six months or more, she said. In a recent study from Oxford, researchers found that people who contracted the coronavirus are “highly unlikely” to contract the disease again for at least six months.

The study, conducted between April and November among 12,180 healthcare workers employed at Oxford University Hospitals, found that 89 of the 11,052 staff without antibodies developed a new infection with symptoms. None of the 1,246 staff with antibodies developed symptomatic infections.

“In some people it may subside after a few months, but we are getting a good indication that the immune response to natural infections lasts for several months,” Van Kerkhove said. “We are about a year into this pandemic so we still have a lot to learn.”

In late August, researchers in Hong Kong reported what appeared to be the first confirmed case of re-infection with Covid after a 33-year-old man who was first infected with the virus in late March appeared to contract the virus again. over four months later, STAT News reported. Although rare, the WHO recognized at the time that re-infection might be possible.

“That doesn’t mean it’s happening a lot; we know it’s possible,” Van Kerkhove said in a live question-and-answer session on August 26.

– CNBC Sam meredith contributed to this report.