Doctor hand holding positive Covid-19 rapid test

Dr. Daniel Griffin, an infectious disease physician in New York, is certain hes seen multiple cases of Covid-19 reinfections. The problem is, hes just not sure how many. Were 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 hes spoken to agree that theyve seen what seem to be Covid-19 reinfections on a regular basis, but their evidence is only anecdotal.

Krutika Kuppalli, an infectious disease physician who also treats Covid-19 patients, also believes she has seen multiple cases of reinfections. Ive had patients that Ive suspected, but theres no way to test, she says. Reinfections are definitely happening, she says, we just dont know on what scale.

According to Alessandro Sette, an immunobiologist at the La Jolla Institute for Immunology, at this point, reinfections are not a huge problem. Sette is a coauthor on a recent study published in the journal Science which suggests that a majority of patients remain immune to Covid-19 reinfection at least eight months after diagnosis.

But as the world looks forward to Covid-19 vaccines and reliable treatments to recover from nearly a year of locking down, those missing numbers could be hiding the true story about how long vaccinations will last, and whether the pandemic can be brought under control as the virus evolves more contagious strains.

The number of patients suffering Covid-19 reinfections is likely a small percentage of the hundreds of thousands of new infections diagnosed worldwide daily, immunologists suggest. The only place that seems to be even attempting to track reinfections is a Dutch news site that has counted over 9,000 cases of suspected reinfection. But to know for sure 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. Countries such as Australia and Taiwan are doing routine sequencing, which could teach scientists more about the Covid-19 immunity as well as new, more contagious variants of Covid-19. On the U.S. frontlines however, most doctors just dont have the time or resources to be sequencing thousands of viral genomes each day. Were swamped, Griffin says, were trying to keep people alive.

Currently, 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 doesnt 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 were doing, she says. Only then will the true scope of Covid-19 reinfections be made clear.

Sette says that reinfections are likely to be mild cases compared to initial cases of the disease though thats 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. This is where better data would reveal the true story.

Tracking reinfections would 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. But more research is needed. Of particular concern is a Covid-19 variant, first discovered in South Africa and now in more than 30 countries, including the U.S. which may prevent patients from developing immunity. But, he says, I dont believe that any of the initial concerns about reinfections have amounted to much so far.

It will matter down the road, however. Knowing how many reinfections are actually occurring provides valuable clues to how long natural immunity to Covid-19 actually lasts. Stanley Perlman, a coronavirus researcher at the University of Iowa, expects that immunity to Covid-19 begins to wane anywhere from between 6 months to a year. Reinfections would be a key indicator of that, he notes, adding I think what one can say is its not permanent immunity.

This article was updated at 6:30pm ET on 1/29/21 for clarity

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Some Experts Claim Covid-19 Reinfections Are Not A Huge ProblemBut Nobodys Tracking The Numbers - Forbes