With the delta variant of SarsCoV2 roaring through the world, doubt has been cast on the concept of herd immunity and the value of the vaccine. Allow me to try and clarify:

– When the SARS-CoV2 virus first surfaced, it was new to everyone’s immune systems worldwide, hence- meeting little resistance- it spread rapidly. With every new variant, we’ve seen further “waves” of spread in susceptible people.

– When most of a population is immune to an infectious disease, this provides indirect protection (or “herd immunity”) to those who are not immune.

– There are 2 ways to achieve herd immunity: either a large proportion of the population gets infected OR gets a protective vaccine. Relying on most of the population to get infected with SARS-CoV2 would be ludicrous because complications can be devastating…hence the urgent need to get as many people as possible vaccinated, ASAP.

– Scientists previously thought that we would need 2/3 of the population to be immune to achieve herd immunity to enable a pre-pandemic lifestyle. However, viral mutations, people’s behaviour and the rate of vaccination affect our herd-immunity prospects.

– Unfortunately, the extremely catchy delta variant arrived as our vaccination programme was coming off its starting blocks, hampering herd immunity hopes.

– It is now likely that a larger % of population immunity (or at least immunity against severe disease) will be needed, more like 80-90%, to achieve relative normalcy. This will need to include children.

– Will “herd immunity” stop all disease transmission? No – but “herd immunity” by vaccination will make COVID a disease without the worrying rate of serious consequences it currently has- so that we can live relatively “normally” with it, as we do with colds, flu and RSV.


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