Nebraska Medicine, a large health network associated with the University of Nebraska Medical Center, recently shared an article on their website. They claim that vaccine-induced immunity is superior to natural immunity, basing their conclusion on one set of data with a small sample size. For some reason, the writers of the article downplayed a prominent Israeli study suggesting natural immunity is superior. The Midwestern group declared that in that Israel-based study, led by Maccabi Health System, a leading HMO, the retrospective study design could not factor away survivorship bias and selection bias. 

Nebraska Medicine bases its conclusion on one CDC-sponsored study finding that 36% of COVID-19 cases do not result in any SARS-CoV-2 antibodies. The study suggests that the different tiers of severity levels may be associated with varying levels of antibodies. While the Israeli study involved hundreds of thousands of people, the CDC-based study included 72 people and 144 plasma samples collected at enrollment and follow-up visits for antibodies specific for the COVID-19 spike protein. They found that 36% of the cohort were “nonresponses.” Weimin Liu, a University of Pennsylvania virologist, led the study. Liu et al. noted that false-positive PCR tests were unlikely but could not be ruled out. Seroconverters and nonseroconverters would also most likely respond differently to the vaccine. Nebraska Medicine did not highlight the limitations of this small study but noticeably pointed out potential shortcomings of the much larger Israeli study.   

Nebraska Medicine completely ignored the Cleveland Clinic study involving over 50,000 healthcare workers. In the article, “Group Think USA,” TrialSite reported  that the Cleveland Clinic actually pulled the study down, and in its place uploaded a plea to get vaccinated. Their explanation was that more research was needed and that the study took place before the emergence of the Delta variant.   

The Cleveland Clinic study involved the testing of 52,238 employees at the prestigious medical center. The study established a positive RT-PCR equating to COVID-19 infection. Two thousand seven hundred fifty-nine of the total subjects were previously infected with SARS-CoV-2, while 54% of that group (1359 people) never received a vaccine. Results showed that over a 5-month period, none of the 2,759 employees became reinfected. The study authors concluded that once an individual is infected with SARS-CoV-2 and recovers, they are unlikely to benefit from vaccination.  

TrialSite respects Nebraska Medicine’s call to get vaccinated, but they should be careful basing an entire argument on a study with 144 samples, with possible false positives, while completely discounting a major real-world study in Israel involving hundreds of thousands of data points.  

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