“Herd immunity” not responsible for Sweden’s control of COVID-19, say researchers
Researchers in Sweden have challenged the interpretation that variable non-pharmaceutical interventions (NPIs) and “herd immunity” protection are responsible for the rise and fall of coronavirus disease 2019 (COVID-19) epidemic waves in hard-hit locations where authorities have not enforced strict NPIs.
Instead, they say that the herd immunity threshold appears to be much lower than previously thought.
However, the team’s study also indicates that these thresholds are unstable and cannot be considered indicative of protection against emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the agent that causes COVID-19.