Another wrinkle in the COVID-19 pandemic has emerged – an increasing number of people who got the virus once have gotten it again.
That's the tale behind recent statistics on Indiana's COVID-19 online dashboard, which Monday reported that 4,568 Hoosiers have experienced “reinfection.”
The reinfection numbers, which have been tallied since Sept. 1, went up 156 in the last week. That represents just 0.5% of all Indiana cases reported from Nov. 16 to Sunday.
State health officials define a reinfection as when a person who has a positive test then has another positive test at least 90 days from the original infection.
Reinfections are different from so-called “breakthrough” cases that occur when people have tested positive, get fully vaccinated, then test positive again at least 14 days from their vaccination.
Some infections may be counted in both categories, Megan Wade-Taxter said in an email.
“If an individual had a positive test, was then vaccinated and then tested positive again 14 days or more from their full vaccination (the requirement for a breakthrough case) and 90 days or more from their initial infection (the requirement for a reinfection), the individual would be included in both counts,” she said.
Reinfections, state health statistics show, are just a small fraction of cases – about a half of a percent since Nov. 15, when a total of nearly 22,000 new cases were tallied.
Breakthrough cases numbered 66,428 as of Monday, just under 2% of fully vaccinated Hoosiers.
State statistics show breakthrough cases are likely to be less severe. They account for only 0.04% of 1,329 hospitalizations of fully vaccinated people and 0.02% of 714 deaths.
Nearly 90% of those deaths were in people 65 or older, and the average age of those who died was 78.
Still, reinfections add to evidence that immunity to COVID-19, whether gained by infection or by vaccine, doesn't last indefinitely, health officials say.
The National Institutes of Health in January reported immunity after falling ill continues up to eight months in 95% of people, but reports in October suggested immunity could wane in as little as three months.
Immunity from a vaccine appears to wane over time, according the federal Centers for Disease Control and Prevention, which recommends a booster vaccine at six months.
An additional 182 residents tested positive for COVID-19, the Allen County Department of Health reported Monday, bringing the total to 64,012. No new deaths were reported to add to the county's 848 fatal cases.
The county has 185,618 fully vaccinated residents, or 52.6% of those eligible. Indiana reported 3,417,959 vaccinated Hoosiers, or 58.2%.
The state Monday tallied 1,914 new cases for a total of 1,077.372 and three new deaths for a total of 16,737.