With COVID-19 cases and hospitalizations continuing to rise sharply in Arkansas, the reasons for many people being reluctant to get vaccinated is being scrutinized. One of the reasons some in the state say they are choosing not to get a vaccine is that they’ve already contracted the disease and therefore have natural immunity.
Dr. Mike Cima, chief epidemiologist for the Arkansas Department of Health said, "anecdotally, I hear that constantly from people that I know who've been infected."
Most people who contract the disease develop antibodies, which offer some protection against future infections. Dr. Jennifer Giovanni, a specialist at the Centers for Disease Control and Prevention, says that protection isn’t always long-lasting.
"So, what we know about those antibodies is that there is very likely a period of time that provides protection from getting infected again. We're not sure quite sure the length of that time—somewhere 6–12 months—but those levels of antibodies in the blood start to decrease with time."
Lower levels of protection from antibodies through a previous infection, combined with the increased contagiousness of the delta variant, may be one reason reinfections are happening more frequently, she said.
"We are seeing more cases of reinfection both in the United States and globally," Giovanni said. "Many of those reinfections are detected or found within certain groups of people that have repeat testing—healthcare workers or employees at care facilities."
For many questions surrounding reinfection, the answers just aren't there, officials say. Testing for COVID-19 reinfections requires genomic sequencing on a scale not available in most states. Sequencing would allow scientists to distinguish between a new case of COVID-19 that might be caused by a variant, as opposed to an ongoing case, commonly referred to as long COVID.
Dr. Cima said another challenge for collecting and studying reinfections within Arkansas was the lack of a formal definition for which cases constitute reinfection. It wasn't until last week that the Council of State and Territorial Epidemiologists provided an official set of criteria, which could be used to classify a case of COVID-19 as a reinfection.
The formal criteria allows cases to be counted as reinfections if the gap between positive tests for SARS-CoV-2 is greater than 90 days, even if genetic sequences of the samples can't be identified as distinct. The possibility of reinfection is one of the factors that can impact achieving herd immunity and an end to the pandemic.
Dr. Giovanni with the CDC and Dr. Cima with the Department of Health both emphasized that the vaccines are the best path to herd immunity in the state.
"Reinfection is possible—to what degree I don't think is fully understood yet," Cima said. "Just from that alone, I would say that the best course of action for somebody who was infected previously is to get the vaccine and get both doses."
The Pfizer, Moderna, and Janssen vaccines are all approved for use in people 12 and older and are widely available in Arkansas.
