An interesting preprint in medRxiv by Milman and others posted March 31, 2021 explores this issue.
Mass vaccination has the potential to curb the current COVID-19 pandemic by protecting vaccinees from the disease and possibly lowering the chance of transmission to unvaccinated individuals.
The high effectiveness of the widely administered Pfizer vaccine in preventing not only the disease but also infection suggests a potential population at the level of effect critical for disease eradication.
This study analysed vaccination records and test results during a rapid vaccine rollout for a large population from 223 geographically defined communities. They found that the rates of vaccination in each community was highly correlated with their later decline in infections amongst the cohort of under 16 years old which were unvaccinated. Their results provided observational evidence the vaccination not only protected individuals vaccinated but also provided cross protection to unvaccinated individuals in the community.
They found that the risk of infection in the unvaccinated cohort decreased in proportion to the rate of vaccination in each community.
They identified a strong negative association between vaccination rate at the community level and the risk of infection for unvaccinated members of the community. They found that higher vaccination rates were associated with a later lower infection rate amongst the unvaccinated cohort.
They concluded that the observed vaccine associated protection of unvaccinated was encouraging but suggested that further studies were required to understand whether and how it might support the prospect of herd immunity and disease eradication.
The London General Practice commends the government on its vaccination programme and encourage all those who are eligible to be vaccinated to ensure that they have it when called.
Dr Paul Ettlinger
The London General Practice