Though rare, it is possible that people who have recovered from Covid-19 could be reinfected, as a recent Hong Kong study suggests, the World Health Organization said Wednesday.
On Monday, researchers released a study that found what appears to be the first documented case of Covid-19 reinfection, in a 33-year-old man. The man was first infected in late March and then again roughly 4½ months later, according to STAT News.
"It doesn't mean that it's happening a lot; we know that it's possible," Maria Van Kerkhove, head of the WHO's emerging diseases and zoonosis unit, said during a live Q&A session. "It is something that we knew could be possible based on our experience with other human coronaviruses."
While much is still unknown about SARS-CoV-2, the virus that causes Covid-19, researchers do know that people who are infected develop some antibody response against the disease once they recover. However, researchers don't yet know how long that immunity lasts, Van Kerkhove said.
The Hong Kong case is also not believed to be the only time someone has been infected with the coronavirus twice, though it's the first documented case, she added.
"This is one example out of 23.5 million cases so far, but we expect that people who are infected do develop an antibody response, they do develop an immune response that lasts for some time, so we're learning," she said.
Van Kerkhove reiterated that whether someone has been infected or not, they should continue following suggested social distancing guidelines, wearing face coverings and following other recommended health precautions.
"Yes, it's possible that we could start to see reinfection, but you know we have the tools in place that can prevent people from getting infected," Van Kerkhove said.
The study also doesn't change the progress being made toward a coronavirus vaccine, Van Kerkhove added. More knowledge about how the body responds to a potential vaccine will be discovered through clinical trials, which are ongoing, she said.
"People think, 'Oh, this means a vaccine won't work.' That's not what this means," she said. "We're still developing vaccines, and there's incredible progress being made on this."