WHO: No evidence to date to suggest COVID-19 antibodies protect against reinfection
There is currently no evidence to suggest that people who recover from COVID-19 and have antibodies are protected against reinfection with the illness, according to a scientific brief from WHO. As a result, although some governments have suggested that the presence of antibodies to SARS-CoV-2 may be an “immunity passport” that allows individuals to travel or return to work under the belief that they are protected from reinfection, there is no evidence to support that.
The development of immunity to a pathogen through natural infection is “a multistep process” that generally occurs over the period of 1 to 2 weeks, according to the brief. The combined adaptive response may clear the virus from the body and could prevent progression to severe illness or reinfection by the same virus, if the response is strong enough. The presence of antibodies in the blood is commonly used to track this process, the brief notes.
WHO officials say that as of April 24, no study has assessed whether the presence of antibodies to SARS-CoV-2 confers immunity to subsequent infection by this virus in humans and that tests that detect antibodies to SARS-CoV-2 in people need further study to establish accuracy and reliability. These tests also need to differentiate between past infections from SARS-CoV-2 and those caused by the known set of six human coronaviruses two of which cause Middle East Respiratory Syndrome and Severe Acute Respiratory Syndrome and four of which cause the common cold.
According to WHO, at this point in the pandemic, there is not enough evidence regarding the effectiveness of antibody-mediated immunity to ensure the reliability of an “immunity passport” or “risk-free certificate” yet. WHO officials also noted that people who believe that they are immune to a second infection because they have received a positive test result may ignore public health advice, which could increase the risk for ongoing transmission of COVID-19.
Experts from the Infectious Diseases Society of American echoed these concerns during a press briefing last week.
“The hope for antibodies has been that the detection of them in the blood represents protection for reinfection,” Mary K. Hayden, MD, FIDSA, IDSA spokesperson and professor of internal medicine and pathology at Rush University Medical Center, said during the briefing. “That's really the million-dollar question.”
Hayden explained that even if antibody immunity is proven, the degree of protection is unknown and could wane over time. Because of this, it should generally be assumed that people with antibodies could be at risk for reinfection and should not change their behavior in any way regarding social distancing and other actions. – by Caitlyn Stulpin
WHO. Immunity passports in the context of COVID-19. https://www.who.int/news-room/commentaries/detail/immunity-passports-in-the-context-of-covid-19. Accessed April 27, 2020.
Disclosures: Healio could not confirm relevant financial disclosures for Hayden at the time of publication.