Does an Israeli study based on medical records of the Maccabi Healthcare Services HMO prove vaccines are less effective than natural immunity? No, that's not true: While the study does indicate people who survived infection with SARS-CoV-2 resisted the delta variant better than those who had been vaccinated, it also notes that people who have been infected and vaccinated fare best of all against reinfection or breakthrough infections.
The paper on which the claim is based is a "pre-print" draft, which has not yet been subjected to review by expert peers to look for data or method flaws nor has it been through editing by a science journal's staff to determine if the methods and conclusions uphold science publishing standards. Also, claiming that natural immunity is better than vaccine immunity is a summary that ignores the fact that natural immunity only accrues to patients who survive an infection, a risky proposition. COVID-19 proved fatal to more than 657,000 Americans by September 2021 and lingering "long COVID" after-effects have been documented that weigh against waiting to be infected instead of seeking vaccination.
Experts in vaccine development say the study includes possible apples-to-oranges comparisons that undermine the broad claim that natural immunity is best. Government public health agencies had not weighed in on the findings by the time this fact check was published.
The claim originated in an August 28, 2021, ZeroHedge website article (archived here) titled "This Ends The Debate" that opens:
Israeli Study Shows Natural Immunity 13x More Effective Than Vaccines At Stopping Delta
Website readers saw this title, description and thumbnail:
'This Ends The Debate' - Israeli Study Shows Natural Immunity 13x More Effective Than Vaccines At Stopping Delta
ZeroHedge - On a long enough timeline, the survival rate for everyone drops to zero
The authors of the Israeli study were markedly less flamboyant than ZeroHedge in describing their findings and pointed out that infection plus vaccination gave the most protection. The paper's conclusion reads as follows:
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.
Because "natural immunity" requires a bout with COVID, infection instead of vaccination may not be the wise choice, wrote Jesse Erasmus. He is a Ph.D. vaccine developer and vaccine researcher in microbiology at the University of Washington Medical School, with published research on the effectiveness of mRNA vaccine technology. The vaccine research team and clinical staff at the University of Washington built COVID expertise during the first major U.S. outbreak of the pandemic.
"... it still does not warrant choosing natural infection over vaccination given the relative risks associated with each of those choices," Erasmus wrote in an September 1, 2021, email to Lead Stories.
There are other problems with the "This ends the debate" summary. Erasmus wrote that some of the comparisons between vaccinated study participants and unvaccinated ones may be apples-to-oranges immunity comparisons:
The conclusion that natural infection drives better immunity than vaccination is not fully supported by the data because the study can't control for differences between the vaccine-version of the sars-CoV2 antigen (spike) and the infecting virus.
Erasmus said it would make sense that someone infected with a variant SARS-CoV2 would be better protected from infection by a variant virus, adding:
In other words, if one were vaccinated with a variant version of spike (matched to the virus that was primarily circulating at that time; most likely Delta) then it may be harder to detect differences in protection between vaccinated or naturally-infected people.
The ZeroHedge claim also cherry-picks the statistics from the study of three months of data from a major Israeli health system. For instance, analysis by the study's authors found the vaccinated were "six to 13" times more likely to get infected than unvaccinated people, not "13 times." And the ZeroHedge summary omits the fact that the study found unvaccinated people were twice as likely to be reinfected as were those who had been infected and had gotten vaccinated.
Instead of the ZeroHedge account of the research, Erasmus suggested people read the earlier explanation published August 26, 2021, in the American Association for the Advancement of Science's Science magazine. That article laid out the risks in oversimplifying the findings, saying in part:
The newly released data show people who once had a SARS-CoV-2 infection were much less likely than never-infected, vaccinated people to get Delta, develop symptoms from it, or become hospitalized with serious COVID-19. The study demonstrates the power of the human immune system, but infectious disease experts emphasized that this vaccine and others for COVID-19 nonetheless remain highly protective against severe disease and death. And they caution that intentional infection among unvaccinated people would be extremely risky.
The Science magazine author talked to vaccine and virology experts who said the findings track with research on other viruses, which shows how powerful natural immunity is, but one pointed out that the weakness of a so-called "retrospective" study like this, which uses a hospital system's patient records, is that no one is making sure to test all participants. People who have been infected and then develop symptoms might be less likely to get tested because they think they are already immune, which one expert said could skew the data.
Prior to publication of this study, the Centers for Disease Control and Prevention and the Food & Drug Administration had strongly discouraged people who think they're better off risking an infection than getting vaccinated. On September 1, 2021, Lead Stories asked both agencies if guidance has now changed and will publish their answers when we receive them.
Dr. Francis Collins, a geneticist and director of the National Institutes of Health (the U.S. government's medical research arm) had, in June 2021, relied on research showing vaccination is more powerful, based on a study published in June 2021 in Science Translational Medicine. Collins, who led the human genome project, wrote in the NIH blog:
The new evidence shows that protective antibodies generated in response to an mRNA vaccine will target a broader range of SARS-CoV-2 variants carrying 'single letter' changes in a key portion of their spike protein compared to antibodies acquired from an infection.
These results add to evidence that people with acquired immunity may have differing levels of protection to emerging SARS-CoV-2 variants. More importantly, the data provide further documentation that those who've had and recovered from a COVID-19 infection still stand to benefit from getting vaccinated.
CDC guidance to users of their public information site tracks with NIH advice, noting that research into the duration of natural immunity is still developing, while the effectiveness and safety of COVID vaccines is well understood, as is the potential for serious illness and even death from COVID. CDC advice is that it is safer to be vaccinated than to gamble on getting infected and developing immunity that way.
Lead Stories also wrote to vaccine makers Pfizer and Moderna to ask their science teams' assessment of the claims that this paper proves vaccination is inferior to natural immunity. Moderna had not replied by the time this was written.
Pfizer's specialist in science journalist relations said Pfizer would not comment on the research paper out of Israel, but said Pfizer and its COVID vaccine development partner BioNTech are developing booster shot regimes to counter the observed fall-off of vaccine immunity over time. In a September 1, 2021, email to Lead Stories, Kit Longley wrote:
The vaccine continues to be highly efficacious in preventing COVID-19, including variants and to date, no variant, including Delta, appears to have escaped the protection of the vaccine. Furthermore, two doses of BNT162b2 continue to show high efficacy from preventing severe disease and hospitalizations.
An ongoing analysis from the Phase 3 study has shown a decline in efficacy against symptomatic infection over time -- from 95 percent at the first two months to low- to-mid-80 percent after 4-6 months post the second dose ... Initial data of a third dose of the current vaccine demonstrates that a booster dose given at least 6 months after the second dose elicits high neutralization titers against the wild type and the Beta, which are 5 to 10 times higher than after two primary doses.
