Since late October, the number of reinfections — people who contracted COVID-19 despite having overcome a prior infection — has risen nearly sevenfold in Indiana, from 258 the week of Oct. 24 to 1,800 the week of Dec. 19, state health officials said earlier this week. State health officials reported 683 reinfections just on Wednesday.

Scientists acknowledge that people previously infected with COVID-19 have some level of natural immunity but that vaccines offer a more consistent level of protection, The Associated Press reported. Much remains unknown about how long natural immunity lasts or how much protection it provides.

“We do not know how long natural antibodies last, and many people have wound up getting COVID more than once,” Dr. Lindsay Weaver, chief medical officer at the Indiana Department of Health, told reporters earlier this week.

The warnings from state officials come as Indiana finds itself amid another surge in infections and hospitalizations and 2.9 million Hoosiers remain unvaccinated in a pandemic that has killed more than 18,300 people in the state, including 201 Bartholomew County residents.

About 30,700 eligible Bartholomew County residents were not fully vaccinated as of Thursday morning, according to the Indiana Department of Health.

The warnings also come as natural immunity is being debated in state legislatures across the country — including in Indiana — with many Republicans who are eager to buck vaccine mandates from Biden administration embracing the argument that immunity from earlier infections should be enough to earn an exemption from the mandates.

They contend that people who have recovered from the virus have enough immunity and antibodies to not need COVID-19 vaccines, and the concept has been invoked by Republicans as a sort of stand-in for vaccines, according to the AP.

Florida wrote natural immunity into state law last month, forcing private businesses to let workers opt out of COVID19 mandates if they can prove immunity through a prior infection, as well as exemptions based on medical reasons, religious beliefs, regular testing or an agreement to wear protective gear, according to wire reports.

The Republican-led New Hampshire Legislature plans to take up a similar measure when it meets this month. Lawmakers in Idaho and Wyoming, both statehouses under GOP control, recently debated similar measures but did not pass them. In Utah, a newly signed law creating exemptions from Biden’s vaccine mandates for private employers allows people to duck the requirement if they have already had COVID-19.

In Indiana, a bill co-authored by state Rep. Ryan Lauer, R-Columbus, includes provisions that would require companies to allow medical or religious exemptions, as well as exemptions for natural immunity for people who survived a bout of COVID19 within the previous six months.

Weaver, however, said there is a risk of reinfection within three months from the previous infection and that previous COVID-19 infections may only offer 19% protection from the omicron variant, which state officials expect will soon become the dominant strain in Indiana.

Data from South Africa and United Kingdom show that two doses of the Pfizer or Moderna vaccine provides approximately 35% protection against the omicron variant, but a booster dose increases that protection to 75%, state health officials said.

Experts also say that natural immunity is also far from a one-size-fits-all scenario, making it complicated to enact sweeping exemptions to vaccines, according to wire reports.

That’s because how much immunity COVID-19 survivors have depends on how long ago they were infected, how sick they were, and if the virus variant they had is different from mutants circulating now. It’s also difficult to reliably test whether someone is protected from future infections.

The Centers for Disease Control and Prevention reported in August that COVID-19 survivors who ignored advice to get vaccinated were more than twice as likely to get infected again, according to wire reports. A more recent study from the CDC, looking at data from nearly 190 hospitals in nine states, determined that unvaccinated people who had been infected months earlier were five times more likely to get COVID-19 than fully vaccinated people who didn’t have a prior infection.

A September study from the CDC found that about one-third of people who survive COVID-19 infections do not have any apparent natural immunity.

Studies also show that COVID-19 survivors who get vaccinated develop extra-strong protection, what’s called “hybrid immunity,” according to wire reports. When previously infected person gets a coronavirus vaccine, the shot acts like a booster and revs virus-fighting antibodies to high levels. The combination also strengthens another defensive layer of the immune system, helping create new antibodies that are more likely to withstand future variants.

Dr. Slade Crowder, CRH vice president of physician enterprise operations and associate chief medical officer, said natural immunity exists — “However, the price you pay is living through COVID and the unknown risk of COVID.”

“You might come through it with inability to smell for the next six months,” Crowder said. “You might come through it with no symptoms. You might come through it and have chronic respiratory symptoms and wheezing. You might have fatigue for the next year. You might die.”

“The whole idea behind a vaccine is you get similar immunity without nearly the same risk,” Crowder said.

The political debate comes after the White House unveiled a host of vaccine mandates earlier this year, sparking a flurry of lawsuits from GOP states, setting the stage for pitched legal battles, according to wire reports. Among the rules are vaccine requirements for federal contractors, businesses with more than 100 employees and health care workers.

In separate lawsuits, others are challenging local vaccine rules using an immunity defense.

But in the medical world, the message is clear.

“Don’t rely on natural immunity to protect you.” Weaver said during a press conference earlier this week. “Even if you had a mild case the first time, your symptoms could be more severe the second time if you are not vaccinated and boosted.”

The Associated Press contributed to this report.

This article was made available through Hoosier State Press Association.