A pedestrian wearing a protective face mask passes the Center for Disease Control and Prevention (CDC) headquarters in Atlanta, Georgia, on Saturday, March 14, 2020.
Elijah Nouvelage | Bloomberg via Getty Images
The U.S. Centers for Disease Control and Prevention made it clear on Friday that the updated quarantine guidelines do not mean that people infected with the coronavirus will be immune to re-infection for the next three months, contradicting reports, according to which the agency's guidelines suggest otherwise.
It was reported on Friday that the CDC's quarantine guidelines, updated on Aug. 3, indicate that people infected with the coronavirus are protected from re-infection for at least three months.
The guidance states that people who are in close contact with someone with Covid-19 should be quarantined, "excluding people who have had COVID-19 in the past 3 months". It also says, "People who test positive for COVID-19 need not be quarantined or retested for up to 3 months as long as they no longer develop symptoms."
The guidelines are "based on studies that showed after three months there was no evidence that people were re-infected after recovering," NBC News reported Friday, citing a CDC official.
However, the CDC later made it clear in a statement that the updated guidelines do not suggest that someone who has been infected with the coronavirus is protected from re-infection for the next three months.
"Contrary to current media coverage, this science does not mean that a person will be immune to re-infection with SARS-CoV-2, the virus that causes COVID-19, for the three months following infection," it said in a statement the CDC.
Instead, the agency "simply suggests" that a person should not need to retest for the next three months after their initial infection, unless that person exhibits symptoms that the CDC has stated are unrelated to another disease can.
That's because someone who tests positive for Covid-19 can test positive again for up to three months after being diagnosed, but is not contagious to others, a CDC official told CNN.
Research has found that the amount of virus that can infect other people decreases significantly after symptoms develop, according to the CDC. Most people cease to be infectious 10 days after their symptoms started and 20 days after their symptoms started, or in people with compromised immune systems, the CDC added.
Global health experts have recognized that it is unknown how long someone infected with the coronavirus and recovered could be protected from re-infection, although it is believed that some immune response is present.
World Health Organization officials said in July that studies suggest that immunity in patients who have recovered from Covid-19 may decline after a few months. Dr. Maria Van Kerkhove, WHO director of Emerging Diseases and Zoonosis, said that while scientists do not have a complete answer, patients "develop some immune response".
"What we don't know is how strong this protection is and how long this protection will last," she said at a press conference at the organization's Geneva headquarters. "So there are a number of studies that try to answer these questions."