“when it comes to vaccine mandates, the relevant question is whether an unvaccinated person with natural immunity is substantially more likely to catch and transmit the coronavirus than a vaccinated person without natural immunity. On that point, medical experts disagree.
Peter McCullough, a Dallas internist and cardiologist with a public health degree who testified in support of psychiatrist Aaron Kheriaty’s unsuccessful challenge to the University of California’s vaccine mandate, argued that the coronavirus “causes an infection in humans that results in robust, complete, and durable immunity”—a protective effect that is “superior to vaccination-induced immunity.” McCullough emphasized that antibody tests reflect only part of the immune response to a COVID-19 infection, which includes “antibodies to the nucleocapsid and to the spike protein, as well as T-helper cells, natural killer cells, B-cells, and innate immunity.”
By contrast, the Berkeley epidemiologist Arthur Reingold argued in the same case that the university’s blanket vaccine requirement was justified because the strength and longevity of natural immunity are unclear. “While individuals who have had a documented case of COVID-19 typically have antibodies to the SARS-CoV-2 virus detectable in their blood and are believed to have a reduced risk of getting COVID-19 again in the months that follow,” he said, “neither the completeness nor the durability of protection against a second case of COVID-19 has been established. The extent to which any such immunity resulting from having had COVID-19 provides protection against new variants of SARS-CoV-2 is also unknown.””
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“A private employer might conclude that a blanket vaccine requirement is easier to administer than one that makes an exception for previously infected people. The latter approach presumably would require documentation of prior infections. It might also require evidence, similar to the tests cited by Norris, of a robust immune response—although vaccinated people don’t have to produce such evidence, even though their immune responses also vary.
As a matter of public policy, however, that added complication does not seem unreasonably burdensome. The OSHA order described by the Biden administration already includes an exception for employees who agree to be tested at least once a week, which is more expensive and harder to arrange than a one-time requirement that employees document their COVID-19 histories.
Jeffrey Klausner, a clinical professor of population and public health sciences at the University of Southern California, co-authored a systematic review in the journal Evaluation & the Health Professions last month that found “the protective effect of prior SARS-CoV-2 infection on re-infection is high and similar to the protective effect of vaccination,” although “more research is needed to characterize the duration of protection and the impact of different SARS-CoV-2 variants.” While the existing evidence is incomplete, Klausner thinks it is strong enough to justify an exception to vaccine requirements. “From the public health perspective,” he told Kaiser Health News, “denying jobs and access and travel to people who have recovered from infection doesn’t make sense.””