Florida Gov. Ron DeSantis speaks to supporters and members of the media before a bill signing Thursday in Brandon, Fla. DeSantis signed a bill that protects employees and their families from coronavirus vaccine and mask mandates. (AP photo)

TALLAHASSEE, Fla. — Republicans fighting President Joe Biden’s coronavirus vaccine mandates are wielding a new weapon against the White House rules: natural immunity.

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.

Florida wrote natural immunity into state law this week as GOP lawmakers elsewhere are pushing similar measures to sidestep vaccine mandates. Lawsuits over the mandates have also begun leaning on the idea. Conservative federal lawmakers have implored regulators to consider it when formulating mandates.

Scientists acknowledge that people previously infected with COVID-19 have some level of immunity but that vaccines offer a more consistent level of protection. Natural immunity is also far from a one-size-fits-all scenario, making it complicated to enact sweeping exemptions to vaccines.

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. For example, a person who had a minor case one year ago is much different than a person who had a severe case over the summer when the delta variant was raging through the country. 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. 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.

“Infection with this virus, if you survive, you do have some level of protection against getting infected in the future and particularly against getting serious infection in the future,” said Dr. David Dowdy of Johns Hopkins Bloomberg School of Public Health. “It’s important to note though that even those who have been infected in the past get additional protection from being vaccinated.”

Studies also show that COVID-19 survivors who get vaccinated develop extra-strong protection, what’s called “hybrid immunity.” 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.

The immunity debate comes as the country is experiencing another surge in infections and hospitalizations and 60 million people remain unvaccinated in a pandemic that has killed more than 770,000 Americans. Biden is hoping more people will get vaccinated because of workplace mandates set to take effect early next year but which face many challenges in the courts.