Yes, an Israeli study did find natural immunity is effective in fighting COVID-19, but health experts still recommend vaccination

Editor’s Note:  This story has been updated to include findings from other studies that both support and contradict the widely shared Israeli study. 

During a Sept. 13 press conference, Florida Governor Ron DeSantis cited an Israel study when speaking about President Joe Biden’s federal vaccine mandate. 

Biden announced on Sept. 9 that all businesses with 100 or more employees must ensure employees are vaccinated or provide a negative test weekly. He also announced all federal employees and federal contractors need to be vaccinated, with the exception of members of Congress and their staff.

“Israel did a study and they compared the protection from a previous infection versus the Pfizer protection, they found the Pfizer did provide protection, but the natural immunity was far stronger,” DeSantis said. 

He said the Cleveland Clinic has come to similar conclusions. 

Since the study was released, several VERIFY viewers asked about the results and sent social media links about the study that were shared widely across social media.

THE QUESTION

Did a study in Israel find natural immunity is more effective than immunity provided by the Pfizer-BioNTech COVID-19 vaccine?

THE SOURCES

• medRxiv (pronounced "med-archive")
• The Cleveland Clinic
• Dr. William Schaffner, Vanderbilt University Medical Center
• Dr. Stuart Ray, Johns Hopkins Hospital
• Centers for Disease Control and Prevention
• The University of California
• Oregon Health & Science University
• National Institutes of Health

THE ANSWER

A team of researchers from Israel studied 2.5 million charts of patients from one of Israel’s largest health systems, Maccabi Healthcare Services. But it is important to note that the study has not yet been peer reviewed and should not be used to guide clinical practice. 

The study found fully vaccinated individuals were at greater risk for COVID-19-related hospitalizations compared to those who were unvaccinated and previously infected.  The study also found that people who received at least one dose of the Pfizer vaccine and had been previously infected were half as likely to be reinfected. 

WHAT WE FOUND

The study was published to medRxiv, which preprints journals and studies from the medical community, on Aug. 25. The researchers analyzed the data from three different groups of people:

• Individuals never infected with the coronavirus, who received the two-dose regimen of the Pfizer/BioNTech vaccine
• Previously infected individuals who had not been vaccinated
• Individuals who have had the coronavirus, and received a single dose of the vaccine, either before or after testing positive for COVID-19. 

The findings did not include information on individuals who previously had COVID-19 and received both doses of the Pfizer vaccine. 

According to the data, people who were fully vaccinated with Pfizer between Jan. 1 and Feb. 28 were more at risk of a breakthrough infection of the highly contagious Delta variant, compared to those who had been previously infected and not vaccinated. Vaccinated individuals were “also at a greater risk for COVID-19-related hospitalizations compared to those that were previously infected,” the study said. 

According to the CDC, a reinfection is a second COVID-19 infection in someone who previously had COVID-19. A breakthrough infection is a COVID-19 infection in someone who has been fully vaccinated. 

Of the more than 32,000 people studied who had been previously infected or were fully vaccinated, there were 238 breakthrough infections in fully vaccinated individuals and only 19 reinfections among unvaccinated people who had been previously infected.  

But a higher level of protection was found among those who had received a single dose of the Pfizer vaccine and had a previous COVID-19 infection. Those individuals were half as likely to be reinfected with COVID-19 than those who did not get the vaccine at all, the study said.

“This study demonstrated that natural immunity confers longer lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity. 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,” the conclusion said. 

Dr. Stuart Ray with Johns Hopkins Medicine told VERIFY “natural immunity is a consequence of having survived COVID.”

“But I don't think our strategy should be for people to get natural immunity because people will die on the path to natural immunity, whereas vaccination is a safe way,” Ray said.

The Cleveland Clinic also published findings in June after studying how the human body’s immune system protects the body after the COVID-19 infection. In August, the clinic issued a new statement that more research is needed and the clinic recommends vaccination.

Florida Governor Ron DeSantis mentioned both of these studies during the Sept. 13 presser, but neither study was peer reviewed, and according to medRxiv, “should not be used to guide clinical practice.”

Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center, told VERIFY Israel is a small country with a very organized health system, and the larger global community can learn from their research. 

Schaffner said despite the evidence suggested in the study, he still recommends getting the full dose of any COVID-19 vaccine.

A study published in August by the CDC also reinforced that there is a reduced risk of reinfection of COVID-19 after receiving the vaccination. This study out of the University of California showed the vaccines are “remarkably effective” at elevating antibody levels to help protect against the coronavirus. 

Researchers from Oregon Health & Science University also studied groups of vaccinated and unvaccinated individuals. They found there is a “novel role for COVID-19 vaccines in protecting hard-hit populations from future waves of the pandemic.”

A blog post from Dr. Francis Collins, the director of the National Institutes of Health (NIH), said that based on findings from a NIH study, a big concern in the natural immunity debate are the variants emerging from COVID-19.

“A key issue as we move closer to ending the pandemic is determining more precisely how long people exposed to SARS-CoV-2, the COVID-19 virus, will make neutralizing antibodies against this dangerous coronavirus. Finding the answer is also potentially complicated with new SARS-CoV-2 ‘variants of concern’ appearing around the world that could find ways to evade acquired immunity, increasing the chances of new outbreaks,” the post said. 

People with acquired immunity “may have differing levels of protection to emerging SARS-COV-2 variants,” it said. Collins wrote that the “hope is the acquired immunity from the vaccines will indeed produce long-lasting protection against SARS-CoV-2 and bring an end to the pandemic.”

So, it’s true that an early study in Israel did find natural immunity provides stronger protection against COVID-19 than the Pfizer vaccine, but it’s dangerous to obtain and vaccines offer protection for both those who have had COVID-19 and those who have not been infected with the virus. 

Also, there are several other studies that exist that contradict the Israeli study’s findings.

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