Immunity gained from COVID-19 infection ignores the risks of getting the disease

A headline circulating online contends that a study done in Israel shows that people who have recovered from COVID-19 have more protection from the virus than those who’ve only been vaccinated. 

The headline is from an article on the conservative website Gateway Pundit, which calls the vaccine "experimental" and refers to Dr. Anthony Fauci, the nation’s leading epidemiologist, as "fuhrer." The headline states:

"New Israeli Study Finds Fully Vaccinated People are at "Greater Risk of Hospitalization" and 13 TIMES MORE LIKELY to Catch Covid-19 Than Those Who Have Recovered and Have Natural Immunity."

The headline was shared in an Instagram post that was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

The headline accurately reflects some of the study’s findings but ignores the study’s limitations, including that only one vaccine was tested, and that other studies have found that COVID-19 poses much greater danger to people who have not been vaccinated.

Without that context, the headline leaves the impression that it’s safer to get COVID-19 and hope to recover than to try to avoid it by getting vaccinated. That’s not true.

The study is what is known as a preprint, meaning it has not yet been vetted by experts. It was posted Aug. 25 on medRxiv.com, which added this note: "This article is a preprint and has not been peer-reviewed. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice."

The study was led by researchers at the Maccabi Research & Innovation Center at Maccabi Healthcare Services in Tel Aviv. They reviewed the records of patients in the Maccabi health system — 674,000 patients who were fully vaccinated and 105,000 who had been infected. Among the 105,000 who had been infected, 63,000 were unvaccinated and 42,000 had received one Pfizer dose three months after recovery.

The researchers said the study is "the largest real-world observational study comparing natural immunity" gained from infection by the coronavirus, with immunity provided by the Pfizer-BioNTech vaccine. They looked at patient records from June through August 2021, when the delta variant was dominant in Israel.

They found:

• People who received both doses of the Pfizer vaccine in January or February 2021 were 13 times more likely to get a breakthrough infection with the delta variant than unvaccinated people who had COVID-19 during the same period were to be reinfected. 

• Over a longer period of time — with infection occurring anytime from March 2020 to February 2021, when different variants were dominant in Israel — fully vaccinated people in the study were six times more likely to become infected and seven times more likely to experience "symptomatic disease" than unvaccinated people in the study.

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• The study "demonstrated that natural immunity affords longer lasting and stronger protection against infection, symptomatic disease and hospitalization due to the delta variant," compared with the Pfizer two-dose vaccine-induced immunity, although previously infected people gained additional protection with a single dose of the vaccine.

The study has been well received by some experts as an indicator of the strength of natural immunity. But it has limitations, including the fact that it was done through record reviews, which are limited by biases in health care seeking behavior — such as testing, mask wearing and social distancing — that may differ among the groups compared, said Dr. Matthew Laurens of the Center for Vaccine Development and Global Health at the University of Maryland.

"This type of study design is not as robust as a prospective study that follows individuals forward in time, testing them at regular intervals and collecting data on symptoms systematically," he said. "Prospective studies should be done to determine if these findings can be replicated.

Gauging immunity by comparing COVID-19 reinfection rates among the unvaccinated with breakthrough infections among the vaccinated ignores the dangers of contracting COVID-19 in the first place and the protections against severe illness that vaccines provide. As we’ve reported:

• As of late July, vaccinated people represented a higher percentage of new COVID-19 cases in Israel than those who are unvaccinated. (This is not unexpected, because Israel has a high overall vaccination rate.) But among Israelis who were fully vaccinated and experienced breakthrough infections, the COVID-19 vaccine was 88% effective in preventing the need for hospitalization and 91% effective against severe illness.

• Israel’s early vaccine campaign, which resulted in more than 60% of its population being fully vaccinated, led to huge reductions in serious cases and deaths in the country.

• In August, we rated False a claim that it’s safer to be unvaccinated than vaccinated. Studies of the general adult population in the United States show that the Moderna and Pfizer-BioNTech vaccines have an 86% to 89% effectiveness rate against infection, and a 96% effectiveness rate against hospitalization, according to the federal Centers for Disease Control and Prevention. Early evidence for the Johnson & Johnson/Janssen vaccine also demonstrates effectiveness against COVID-19, but more studies are underway, CDC said.

"The suggestion that you might be better off getting infected versus vaccinated does not take into account the inherent risks associated with COVID-19 infection, including death," Laurens said. "Vaccination is the best prevention. This has been clearly shown in multiple prospective, randomized, double-blinded clinical trials, which are the very highest quality for clinical studies."

Experts told the journal Science that seeking immunity through deliberate infection would put unvaccinated people at significant risk of severe disease and death, or the lingering, significant symptoms of what has been dubbed Long COVID.

The Maccabi study shows the benefits of natural immunity, said University of Washington immunologist Marion Pepper, but "doesn’t take into account what this virus does to the body to get to that point."  

A headline widely shared on social media stated: "New Israeli study finds fully vaccinated people are at ‘greater risk of hospitalization’ and 13 times more likely to catch COVID-19 than those who have recovered and have natural immunity."

The study, which has not been peer reviewed, found that people who had been infected with COVID-19 had greater protection against becoming reinfected with the virus’ delta variant than vaccinated people had against infection.

But the headline’s suggestion that people are better off going unvaccinated ignores the fact that peer-reviewed studies repeatedly have found that vaccinated people are more likely to avoid hospitalization or death if they become infected.

The statement is partially accurate but leaves out important details. We rate it Half True.