Some claim they had virus twice
Scientists trying to study what reinfection means
By medical standards, Nicole Worthley is considered extraordinarily rare. She was diagnosed with COVID-19 on March 31 and again in September.
She was walloped both times, with a fever for six weeks and side effects all summer before round two kicked in.
But she can’t prove she had COVID-19 twice. That requires genetic testing of both infections, which has only happened a few dozen times in the world, and never in South Dakota where she lives.
Many states are keeping track of claims of reinfection – South Dakota, for example, is studying at least 28, while Washington state is investigating 120 – but they are still considered extremely unusual, according to health experts, including the World Health Organization.
In Colorado, 241 people have had a second positive PCR test more than 90 days after the first one. “All are investigated as cases, including isolation instruction for the case and quarantine instruction for their close contacts,” according to a Colorado Department of Health and Environment spokesperson.
The U.S. Centers for Disease Control and Prevention said in a statement that it is investigating some possible reinfections but has not yet confirmed any. It only considers infections more than 90 days apart to be possible reinfections; otherwise, someone’s illness is likely a lingering infection.
Worthley said she’s not sure which is worse: Being able to be reinfected, or having a lingering virus that could flare up anytime.
“Whether or not I personally have a proven reinfection isn’t to me as important as it’s possible that you can get it again,” she said. “Or, if you don’t believe that, then it’s possible that for six straight months you can have COVID-19, still test positive for COVID-19 and still be actively ill from it – because I don’t think there’s a lot of understanding of
that right now.”
No one knows how long the immune system can keep someone safe from COVID-19 after infection.
Some diseases like measles are one and done. Once infected or vaccinated and the immune system typically provides protection forever. With other viruses, like the common cold – some of which are closely related to the coronavirus that causes COVID-19 – protection might not last a year, or even a season.
COVID-19 was discovered less than a year ago, so scientists don’t yet know how long the body can fight it off.
The answer has implications for the longevity and effectiveness of vaccines, the possibility of communities developing so-called herd immunity where the virus no longer spreads because so many people have already been infected, and how those infected once should feel and behave.
Worthley believes she is among the 28 people that the South Dakota Department of Health has said it’s investigating for reinfection, although she’s yet to hear from anyone at the state.
So far, only a few dozen people worldwide have been confirmed to have been infected twice with SARS-COV-2, the virus that causes COVID-19.
One man in Hong Kong didn’t know he’d been infected a second time. He only found out when he was routinely tested on his return home from a trip to Italy. Another man, just 25, in Nevada, was sicker the second time.
In both cases, genetic analysis of the infections proved that they were infected twice, with slightly different versions of the virus – not just long-suffering. The World Health Organization has received reports of reinfections, but they are relatively rare so far.
“Our current understanding of the immune response is that the majority of people who are infected mount an immune response within a few weeks of infection,” a WHO spokesman said via email. “We are still learning about how long the antibodies last. So far, we have data that shows that the immune response lasts for several months.”
In a statement, a CDC spokesperson said the agency is actively investigating a number of suspected cases of reinfection, though none has been confirmed.
“CDC’S investigation of the reinfection phenomenon is in its early stages,” he said.
Jeffrey Shaman, a professor at the Columbia University Mailman School of Public Health, who has been investigating reinfections, said scientists have a lot of open questions.
Among other things, he said, they want to know: How often reinfection can happen, are people contagious with the second infection and for how long, and do people who are reinfected have less severe cases the second time – or are they worse off?
To answer those questions, researchers like him have to figure out what’s behind these reinfections, Shaman said.
People might fail to generate immune memory with the first infection, and need repeated exposure to build up immunity. If so, a vaccine might have the same problem, and it won’t be very effective.
Or people might get antibodies to the virus and then lose them, Shaman said. In that case, a vaccine’s benefit might not last long.
The worst-case scenario would be what happens with dengue. In the case of that mosquito-borne tropical disease, someone can get sicker if infected a second time, or infected after getting a vaccine. Then, a vaccine could actually be harmful – though there’s no evidence that’s the case with COVID-19.
Sometimes diseases that start as outbreaks can become endemic, returning year after year.
The 1918 flu, for instance, was so devastating because it was new and no one had built up resistance, Shaman said. It came back repeatedly but “didn’t have the huge pulses of people dying,” he said, possibly because their bodies had built up some immunity to it.
If that’s the case with COVID-19, then a vaccine, even a partially effective one, could have a big benefit by exposing people to the virus and helping them build up tolerance, he said.
It’s not yet clear how long someone is contagious with COVID-19 if their symptoms linger or recur.
Until scientists learn the answers to these questions, people who have been infected once shouldn’t assume they’re protected indefinitely, and should continue to wear masks, wash hands, maintain distance and avoid crowds, Shaman said.
“The only way we’re going to get a sense of it is over time,” he said. still