“…When the vaccine rollout began in mid-December 2020, more than one quarter of Americans—91 million—had been infected with SARS-CoV-2, according to a US Centers for Disease Control and Prevention (CDC) estimate.1 As of this May, that proportion had risen to more than a third of the population, including 44% of adults aged 18-59 (table 1).
|Age group (years)||No of infections (millions) (95% uncertainty interval)||Population in 2019 (millions)||% previously infected (95% uncertainty interval)|
|0-17||26.8 (22 to 33.1)||73||37 (30 to 45)|
|18-49||60.5 (50.4 to 73.2)||138||44% (36 to 53)|
|50-64||20.4 (17.0 to 24.6)||63||32% (27 to 39)|
|65+||12.3 (9.9 to 15.5)||54||23% (18 to 29)|
|All ages||120.3 (103.3 to 140.9)||328||37% (31 to 43)|
* Sources: CDC (estimated infections) and US Census (2019 estimated population).
The substantial number of infections, coupled with the increasing scientific evidence that natural immunity was durable, led some medical observers to ask why natural immunity didn’t seem to be factored into decisions about prioritising vaccination.234
“The CDC could say [to people who had recovered], very well grounded in excellent data, that you should wait 8 months,” Monica Gandhi, an infectious disease specialist at University of California San Francisco, told Medpage Today in January. She suggested authorities ask people to “please wait your turn.”4
Others, such as Icahn School of Medicine virologist and researcher Florian Krammer, argued for one dose in those who had recovered. “This would also spare individuals from unnecessary pain when getting the second dose and it would free up additional vaccine doses,” he told the New York Times.5
“Many of us were saying let’s use [the vaccine] to save lives, not to vaccinate people already immune,” says Marty Makary, a professor of health policy and management at Johns Hopkins University.
Still, the CDC instructed everyone, regardless of previous infection, to get fully vaccinated as soon as they were eligible: natural immunity “varies from person to person” and “experts do not yet know how long someone is protected,” the agency stated on its website in January.6 By June, a Kaiser Family Foundation survey found that 57% of those previously infected got vaccinated.7
As more US employers, local governments, and educational institutions issue vaccine mandates that make no exception for those who have had covid-19,8 questions remain about the science and ethics of treating this group of people as equally vulnerable to the virus—or as equally threatening to those vulnerable to covid-19—and to what extent politics has played a role…”