World Health Organization Director-General Tedros Adhanom Ghebreyesus R will speak at a daily briefing in Geneva, Switzerland.
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World Health Organization officials warned on Friday that the latest data suggests that, although it is rare for people once infected with the coronavirus to become re-infected as the antibody response declines.
“We’ve seen the number of people infected increase steadily, but we’ve also seen data show that protection may not last a lifetime, so re-infections may occur,” said Dr. Mike Ryan, WHO health director of the emergency program, the organization said at a press conference in Geneva. “So the question is: What is the level of protection in society?”
Re-infection means that a person became infected with the virus, recovered, and later re-infected, according to the U.S. Center for Disease Prevention and Control. Based on the CDC’s experience with other viruses, re-infection with Covid-19 is expected, the agency said.
However, researchers are trying to determine the likelihood and frequency of re-infection, including how severe reinfection can be 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 were still trying to determine how long the antibody response would last after someone became infected with the virus.
“What we understand is 90[%] 100% of people infected with the coronavirus develop an antibody response, whether they have a mild infection, an asymptomatic infection, all the way to a severe infection, ”he said.
Ongoing research shows that the immune response can take six months or more, he said. In a recent Oxford study, researchers found that people infected with the coronavirus were “very unlikely” to be re-infected for at least six months.
A study of 12,180 health workers at Oxford University Hospitals between April and November found that 89 of the 11,052 workers without antibodies developed new symptoms of infection. None of the 1246 employees with antibodies developed a symptomatic infection.
“For some people, it may decrease in a few months, but it’s a good indication that the immune response to a natural infection takes a few months,” Van Kerkhove said. “We’ve been in this pandemic for about a year, and so we still have a lot to learn.”
In late August, Hong Kong researchers reported the first confirmed case of Covid re-infection after a 33-year-old man who was first infected with the virus at the end of March was re-infected more than four months later, STAT News reported. The WHO recognized at the time that although rare, re-infection was possible.
“That doesn’t mean a lot is happening; we know it’s possible,” Van Kerkhove said at a live Q&A meeting on Aug. 26.
– CNBCs Sam Meredith contributed to this report.