The U.S. Centers for Disease Control and Prevention clarified on Friday that its updated quarantine guidance does not imply people who are infected with the coronavirus are immune to reinfection in the following three months, contradicting reports that said the agency's guidance suggests otherwise.
On Friday, it was reported that CDC guidelines on quarantining, which were updated on Aug. 3, indicate that people who are infected with the coronavirus are protected from reinfection for at least three months afterward.
The guidance says that people in close contact with someone with Covid-19 should quarantine, "excluding people who have had COVID-19 within the past 3 months." It also says "people who have tested positive for COVID-19 do not need to quarantine or get tested again for up to 3 months as long as they do not develop symptoms again."
The guidance is based "on studies that found that, after three months, there was no evidence of people getting re-infected after recovering," NBC News reported Friday citing a CDC official.
However, the CDC later clarified in a statement that the updated guidance does not suggest someone who was once infected with the coronavirus is protected from reinfection for the following three months.
"Contrary to media reporting today, this science does not imply a person is immune to reinfection with SARS-CoV-2, the virus that causes COVID-19, in the 3 months following infection," the CDC said in a statement.
Instead, the agency "simply suggests" that retesting someone in the following three months after their initial infection is unnecessary unless that person shows symptoms that can't be associated with another illness, according to the CDC statement.
That's because someone who has tested positive for Covid-19 can still test positive again for up to three months after diagnosis but not be infectious to others, a CDC official told CNN.
Research has found that the amount of virus that can infect other people drops significantly after people develop symptoms, the CDC said. Most people are no longer infectious 10 days after their symptoms begin and 20 days for people with severe illness or those who are immunocompromised, the CDC added.
Global health experts have acknowledged that it's unknown how long someone who's infected with the coronavirus and recovered might be protected from reinfection, though it's believed there is some level of immune response.
World Health Organization officials said in July that studies suggest immunity in patients who recovered from Covid-19 may wane after a few months. Dr. Maria Van Kerkhove, head of the WHO's emerging diseases and zoonosis unit, said that while scientists don't have a complete answer, patients "do mount some level of an immune response."
"What we don't know is how strong that protection is and for how long that protection will last," she said at a news conference at the organization's Geneva headquarters. "So there are a number of studies under way that are trying to answer these questions."