Since the start of the coronavirus pandemic, scientists and doctors have been working day and night to find ways to combat the global crisis. One of those solutions has been developing an antibody test to determine whether or not you’ve been exposed to COVID-19. But the question remains: If you have been exposed, does that mean you’re immune from catching it again?
Knowing whether survivors are now immune is essential, because it will dictate how and when communities can start to resume their normal lives. If people who have recovered from coronavirus are now immune, they may be able to safely go back to work, for example.
An immunity task-force has been established in Canada, according to Chief Medical Officer Theresa Tam, to look at reinfection among Canadians previously diagnosed with COVID-19. Health Canada has approved a blood test, known as a serology test, to detect COVID-19 antibodies, which could help identify individuals immune to the virus, but Tam cautions that it's too soon to know whether individuals previously infected have immunity to the virus. The length of time antibodies stick around in the body is also unknown.
The new serological test will be given to 1-million Canadians over the next two years to look at the virus in the general population as well as more at-risk groups, including health-care workers and seniors. "We're hoping to see rapid implementation of the actual population surveys, both general and those focusing on specific communities, geographies, (and) occupational groups,” said Tam.
"Given what we know about the recovery from coronaviruses in general or even any infectious disease with very few exceptions, when you have antibodies present it very likely indicates a degree of protection," said Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, recently. But, he noted, in this case, immunity has not been formally proven by long-term natural history studies. "You can make a reasonable assumption that it would protective, but natural history studies over a period of months to years will then definitively tell you if that's the case," explained Dr. Fauci.
Dr. Fauci also said that as of now, we don't know what antibody titer (a measurement of how much antibody an organism produces) is required for a person to be considered immune. We also don't know how long immunity would persist after recovery.
What's more, the SARS-CoV-2 virus, which causes COVID-19, may mutate over time, according to scientists at the Los Alamos National Laboratory. If that were true, people who recovered could potentially be vulnerable to catching a newly mutated strain again. The researchers released a paper that claimed to reveal “the emergence of a more transmissible form” of the virus. But those conclusions were called "overblown" by Lisa Gralinski of the University of North Carolina, one of the few scientists in the world who specializes in coronaviruses, in an interview with The Atlantic.
Another reason experts are hesitating: Antibody tests are far from perfect. If a person's test comes back positive for the presence of coronavirus antibodies, there's still a 10 to 30% chance that they may be from another cold or infection, not COVID-19 in particular, Shawn Nasseri, MD, who practices in Beverly Hills, previously told Refinery29.
Even if the antibodies detected are from COVID-19, as Dr. Fauci pointed out, we don't know if they're present in high enough levels to offer immunity. "There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection," the World Health Organization reports.
"As we see larger numbers of people, then we will have a better understanding of the patients who show strong immunity and statistics reflecting that they are not getting the virus," said Dr. Nasseri in a follow-up interview with Refinery29. "I would say we have at least a couple more months before we have adequate data."
COVID-19 has been declared a global pandemic. Go to the Public Health Agency of Canada website for the latest information on symptoms, prevention, and other resources.