If we look at the World Health Organization (WHO) goal to fully vaccinate at least 70% of the population in every country worldwide by June 2022, then not surprisingly, the progress is sketchy - 109 out of 193 countries will fail to meet this target. More alarmingly, 36 countries have not been able to vaccinate even 10% of their population.
Despite knowing it is more important to ensure that unvaccinated people get their primary vaccine shots on high priority, rich and poor nations alike are going ahead with providing booster doses to the fully vaccinated people. Some countries like Israel and Germany are giving out the fourth dose (second booster). Even a call given by the WHO for a global moratorium on boosters till December 2021, did not deter the rich nations from going ahead with the third shot of vaccines.
One in four vaccine shots used as a booster
Currently, one in every four vaccine-doses is being administered as a booster dose in one of the 126 countries that have included booster-recommendation in their national guidelines for management of the pandemic. In many of these countries, which are administering booster doses, the coverage rates for complete primary vaccination are below 30%.
So should we keep providing booster after booster to those already vaccinated, rather than reaching out to the unvaccinated too? Or do we have to do both with equity and science as the guiding stars?
According to the WHO, booster doses are administered to a fully vaccinated person if, with time, the immunity and clinical protection has fallen below a rate deemed sufficient in that population. The objective of a booster dose is to restore vaccine effectiveness from that deemed no longer sufficient.
WHO Strategic Advisory Group of Experts (SAGE) on Immunization had met on 19 January 2022 and looked at the scientific evidence regarding boosters. There is emerging, yet limited, evidence of how boosters help increase vaccine efficacy against both variants (Delta and Omicron) of the SARS-CoV-2 virus. There is no booster data on long-term duration of protection in terms of hospitalization, severe disease, or death. Scientific studies on Omicron variant are very few and with limited follow up. More data will be needed to understand the potential impact of booster vaccination doses on the duration of protection against not only severe, but also mild disease, infection, and transmission, particularly in the context of emerging variants.
Dr Soumya Swaminathan, WHO Chief Scientist and former Director General of the Indian Council of Medical Research, lists three aspects that can affect immunity:
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