Some Experts Claim Covid-19 Reinfections Are ‘Not A Huge Problem’—But Nobody’s Tracking The Numbers
Doctor hand holding positive Covid-19 rapid test
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Dr. Daniel Griffin, an infectious disease physician in New York, is certain he’s seen multiple cases of Covid-19 reinfections. The problem is, he’s just not sure how many. “We’re seeing a lot of people that we took care of back in the early spring” returning to the hospitals with Covid-19 symptoms, he says. Other physicians that he’s spoken to agree that they’ve seen what seem to be Covid-19 reinfections on a “regular basis,” but their evidence is only anecdotal. To know for sure whether or not a patient is suffering a Covid-19 reinfection would require a genetic sequence of the virus in both the first and second diagnosis to compare whether the new infection is a genetically distinct virus or the same from the original infection. Most doctors on the frontlines just don’t have the time or resources to be sequencing thousands of viral genomes each day. “We’re swamped,” Griffin says, “we’re trying to keep people alive.”
Krutika Kuppalli, an infectious disease physician who also treats Covid-19 patients on the frontlines, also believes she has seen multiple cases of reinfections. “I’ve had patients that I’ve suspected, but there’s no way to test,” she says. Reinfections are definitely happening, she says, “we just don’t know on what scale.”
Not all scientists agree that reinfections should be a priority right now, however. Alessandro Sette, an immunobiologist at the La Jolla Institute for Immunology, says, “at this point, reinfections are not a huge problem,” compared to the ever-growing number of new Covid-19 infections. Sette was a coauthor on a recent study published in the journal Science found that components of immune memory to Covid-19 were still detectable in most cases at least eight months after infection.
These contrasting statements highlight one of the mysteries of the Covid-19 epidemic: how long does immunity last, and how durable is it? Whether people are being reinfected with the disease is a key metric for making this determination. But here’s the problem: apart from a Dutch news agency tracking reinfection case reports (it has a bit over 9,000 suspected cases to date), there is no centralized collection of reinfection numbers.
One major hindrance here is that there’s a lack of genetic surveillance in the United States, unlike countries such as the United Kingdom or South Africa. This leaves researchers and public health officials with the knowledge that reinfections are occurring— but no clear idea how many. This is a problem for multiple reasons: without knowing how many reinfections are actually occurring, it’s not clear how durable the immune response is to SARS-CoV-2 on a large scale. It also makes it nearly impossible to tell if the new, more contagious variants are more likely to cause reinfection.
It’s important to note that reinfections are most likely not a common phenomenon. Even thousands of reinfections are a tiny percentage of the approximately 100 million global cases of Covid-19 that have been reported. But without accurately tracking how many reinfections are occurring, scientists can’t tell whether that number will start to increase.
Knowing how many reinfections are actually occurring can give us valuable clues to how long natural immunity to Covid-19 actually lasts. Stanley Perlman, a coronavirus researcher at the University of Iowa, says, “I think what one can say is it’s not permanent immunity.” He expects that immunity to Covid-19 begins to wane anywhere from between 6 months to a year. Griffin, the doctor in New York, agrees. He says that he expects more reinfections to occur in the coming months as we pass the one-year mark of the virus being detected in the U.S.
Meanwhile, Sette says the evidence for reinfections is “anecdotal at this point,” though he does think there are likely hundreds of cases. While his research has found that 90% of people have durable immune responses after recovering from Covid-19, that still means that about 10% are susceptible to reinfection. He says this is proof that even after someone has recovered from Covid-19, they should still be responsible when it comes to wearing face masks and social distancing. “How would you feel driving a car if the car has a 90% chance that the brakes work?” he asks.
Sette also says that reinfections are likely to be mild cases compared to initial cases of the disease — though that’s not always true. An article published in medical journal the Lancet last October detailed a case of Covid-19 reinfection of a 25-year old man in Nevada whose second infection was more severe than his first. Griffin says he has also personally seen at least one case of reinfection where the first infection was beaten at home, but the patient had to be hospitalized to treat the second infection.
Cases of reinfection can also teach scientists more about the new, more contagious variants of Covid-19 that are currently circulating the globe. Current data “indicates that some of these SARS-CoV2 lineages might have a higher capacity to reinfect people,” says Ramon Lorenzo Redondo, a professor of infectious diseases at Northwestern. Redondo cautions, however, that more research is needed. Of particular concern is the variant 501Y.V2, first discovered in South Africa and now in more than 30 countries, including the U.S. For this variant, there is “data corroborating concerns regarding the potential for decreased antibody recognition,” says Jason Kindrachuk, a professor of viral pathogenesis at the University of Manitoba. But, he says, “I don’t believe that any of the initial concerns about reinfections have amounted to much so far.”
So, how can the U.S. and the rest of the world better keep track of reinfections? The key is faster, cheaper genomic sequencing. Countries like the U.K. have looked at thousands of genome sequences in part thanks to the concerted efforts of organizations like the Covid-19 Genomics UK Consortium. Meanwhile, the U.S. ranks as 43rd worldwide when it comes to genomic sequencing of Covid-19. “The United States is not doing enough,” says Jessica Malaty Rivera, the communications lead for The COVID Tracking Project. Rivera says that she doesn’t believe states are tracking it on a local level, and there is no central database where physicians across the country can report suspected or confirmed cases of reinfections.“The only way to properly track reinfections is to do much more genomic sequencing than we’re doing,” she says. Only then will the true scope of Covid-19 reinfections be made clear.