Fact-checking DeSantis on COVID-19 natural immunity

Florida Gov. Ron DeSantis is pushing back against vaccine mandates, particularly for people who already have been infected.

During a stop in Gainesville, DeSantis accused city officials of threatening to "destroy" the jobs of city workers. The Gainesville City Commission has given employees until Oct. 31 to get fully vaccinated. At an Aug. 5 meeting, the city attorney seemed to take a hard line, saying "You have a choice. If you don’t want to get vaccinated, then your choice is to seek employment elsewhere."

DeSantis said mandates ignore the natural immunity many first responders gained from getting the disease earlier in the pandemic.

"The ones that have recovered have very strong immunity," DeSantis said Sept. 13. "That’s very clear from every study that’s been done."

At a Tampa event later the same day, DeSantis mentioned a study out of Israel.

"They compared the protection from a previous infection versus the Pfizer protection. They found that Pfizer did provide protection, but the natural immunity was far stronger," he said.

We looked into the studies on natural versus vaccine-driven immunity, and natural immunity delivers a lot of protection. But researchers also see some signs that the best protection comes from a 1-2 punch of natural immunity plus one dose of vaccine.

Importantly, natural immunity comes at a much higher personal risk than vaccination, and verifying natural immunity is more technically complex than verifying vaccination status.

Israeli researchers looked at thousands of medical records. In one part of the study, they compared over 16,000 patients who were previously infected and never vaccinated against another 16,000 who had only received the Pfizer vaccine. They factored in age, gender, health and when they were infected or vaccinated.

They found that the vaccinated group that did not report any prior infection was much more at risk of catching COVID-19 later on than those who had already been infected but not vaccinated. There was a 13-fold higher risk of a breakthrough infection compared with reinfection.

"This study demonstrated that natural immunity confers longer-lasting and stronger protection against infection," the Aug. 25 study said.

They noted that the period they examined included the time when the delta variant was dominant in Israel. This study was released immediately, and still needs to be peer reviewed. Several factors might have shaped the results. Researchers might have missed a number of asymptomatic infections because those people would have less reason to be tested. And there was no control for social distancing and mask wearing habits that would affect the risk of infection.

New work out of Rockefeller University adds weight to the Israeli findings. It focuses on the body’s molecular level defenses against the virus, especially the memory B cell. Long after the initial antibody response fades, these cells hold on to the blueprint of the virus and when they see it in the body months later, they crank up the antibodies to crush it.

Both vaccinations and natural exposure build memory B cells. But the Rockefeller team found that the memory B cells produced through natural infection are more robust. They continue to evolve over the months, while the vaccination-driven memory B cells stopped changing after about two months. When facing variants, the naturally occurring memory B cells delivered better protection.

The research is preliminary and future work might change the picture. But for now, there’s reasonable evidence that someone who recovered from the virus has protection that’s at least as good as that from a vaccine.

What DeSantis didn’t mention is that the people who recover and then get vaccinated seem to get higher protection against the virus.

In the Israel study, the effect was modest, but visible.

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"Individuals who were both previously infected with SARS-CoV-2 and given a single dose of the vaccine gained additional protection against the delta variant," researchers wrote.

An August CDC study of Kentucky patients who were infected by COVID-19 in 2020 found that by mid-2021, the ones who never got vaccinated were more than twice as likely to get reinfected.

However, the CDC researchers noted, vaccinated people might be less likely to get tested, which would drive down the reported reinfection numbers.

A study published in April 2021 from a team at Oregon Health and Science University found that vaccinations boosted the antibody response against virus variants among people with natural immunity. Another study based on a small number of health care workers in Maryland reached a similar conclusion, saying those who had been previously infected benefited from a single dose of either the Moderna or Pfizer vaccines.

On the downside, a British study published in the Lancet reported that people who were vaccinated after they had been infected were more likely to report side effects such as headache or fever than those who hadn’t been infected before. There were nearly no reports of side effects after one week.

We lack a clear picture on the variation among people in the strength of natural immunity, and how long it lasts, especially as variants emerge.

As is always true with COVID-19, the research is ongoing and the findings we see today might be supplanted by new work.

DeSantis’ overall stance on vaccinations has become less clear over time. When the vaccines first arrived, he promoted them heavily, especially for the elderly. Now, he has pushed back against the mandates coming from the White House, saying Washington lacks the legal authority. At his event in Gainesville, he stood silent as city workers came to the podium and spread clear falsehoods about the safety of the vaccines. One man said the vaccines change a person’s RNA.

DeSantis press secretary Christina Pushaw told the Tampa Bay Times that the governor supports vaccines.

"Getting vaccinated is a smart choice to protect yourself from severe COVID outcomes," Pushaw told PolitiFact.

But doctors worry the focus on natural immunity dilutes the pro-vaccine message.

The lead author of the Rockefeller research underscored that relying on natural immunity is a high-risk strategy.

"While a natural infection may induce maturation of antibodies with broader activity than a vaccine does, a natural infection can also kill you," said immunology center director Michel  Nussenzweig in an August university article. 

Dr. Matthew Laurens of the University of Maryland’s Center for Vaccine Development and Global Health echoed that point.

"Vaccination is the best prevention," Laurens told PolitiFact Aug. 31. "This has been clearly shown in multiple prospective, randomized, double-blinded clinical trials, which are the very highest quality for clinical studies."

DeSantis said people who have recovered from COVID-19 have very strong protection.

The studies are preliminary, but they do find that surviving COVID-19 leaves people with robust immunity, even stronger than immunity gained through vaccination.

However, some of the same research found that giving a single vaccine dose to those who had recovered provided the best protection.

DeSantis’ point is accurate but needs more context. We rate this claim Mostly True.