The World Health Organization has changed the definition of “herd immunity,” eliminating the pre-COVID consensus that it could be achieved by allowing a virus to spread through a population, and insisting that herd immunity comes solely from vaccines.
The change occurred on a section of the WHO’s website entitled ‘Coronavirus disease (COVID-19): Serology, antibodies and immunity’.
The WHO’s original definition (archived here) states that herd immunity “happens when a population is immune either through vaccination or immunity developed through previous infection. This means that even people who haven’t been infected, or in whom an infection hasn’t triggered an immune response, they are protected because people around them who are immune can act as buffers between them and an infected person.”
The original definition fails to identify the pre-COVID consensus on what is meant by “herd immunity,” which is when a population becomes protected against a virus because enough people have been infected with it to create community immunity.
However, the WHO’s updated version is even more extreme, insisting that herd immunity can only be achieved by mass vaccination programs.
“‘Herd immunity’, also known as ‘population immunity’, is a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached,” states the WHO website, adding, “Herd immunity is achieved by protecting people from a virus, not by exposing them to it.”