SAN DIEGO — Data from San Diego County suggest that few residents have gotten COVID-19 twice so far, echoing findings from researchers across the globe.
The Union-Tribune asked the County of San Diego Health and Human Services Agency for the number of people who've tested positive for the coronavirus twice, with their second test at least three months after their first. That cutoff is based on a Centers for Disease Control and Prevention report that an infected person can shed virus for up to three months after they first show symptoms
"Fewer than 10" San Diegans met those criteria, according to communications officer Sarah Sweeney.
That's a tiny fraction of the more than 70,000 people who've tested positive for COVID-19 in the region. And Sweeney cautions that the county isn't certain these are genuine cases of reinfection and not tests picking up remnants of a person's first infection.
To figure that out, researchers would have to sequence viral samples from both tests and compare them. Clear genetic differences between the samples would be a strong sign that someone was infected twice.
That's what scientists did to identify the first confirmed case of COVID-19 reinfection — a man living in Hong Kong who tested positive for the coronavirus (SARS-CoV-2) in late March and again in mid-August.
UC San Diego infectious disease expert Chip Schooley is the editor of the journal of Clinical Infectious Diseases, where the study published. He says it's no surprise that researchers are finding instances of COVID-19 reinfection.
"We knew this would be the case," Schooley said. "Other coronaviruses had the same experience: You develop immunity during a bout of infection, the immunity wanes and then the virus comes back around again and you get infected. And that's what's happening with this coronavirus as well."
Local researchers say that's not necessarily cause for concern.
Notably, the first person with a confirmed COVID-19 reinfection had mild symptoms during his first bout of disease and no symptoms the second time.