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The Nuance
Herd Immunity May Play a Bigger Role Than We Thought
Going forward, hard-hit communities could enjoy a measure of immunity-derived protection
During the first months of the pandemic, so-called herd immunity was a hot topic of conversation among public-health officials, politicians, and the media. The term refers to the percentage of people within a population that must have immunity to a virus in order to effectively retard or block its spread.
Early on, most experts estimated that the herd immunity threshold for SARS-CoV-2 was somewhere north of 60%, meaning that 60% or more of the population would need to develop immunity — either via vaccine or infection — in order to snuff out the virus. But those early estimates were based on incomplete data and overly simplistic statistical models — limitations that most infectious disease experts were quick to highlight at the time.
A lot of the data on the novel coronavirus remains incomplete. For example, researchers still don’t know just how infectious SARS-CoV-2 really is or how long immunity lasts following an infection. These two pieces of information are crucial inputs when it comes to accurately modeling herd immunity thresholds. Further complicating matters: The answers to both of these questions may vary…
