Covid-19 vaccinations may become annual events

In the middle of acute vaccine shortage in many parts of the world, some wealthier countries are administering ‘booster’ doses of the Covid-19 vaccine to their citizens. The US, for example, is all set to start giving booster shots to certain categories of immunocompromised among its citizens from September 20. This is eight months after these individuals have received their second shot in the case of Pfizer or Moderna vaccines. More studies are needed for extra shots of the single-dose Johnson & Johnson vaccine. Several other countries such as Germany, Israel, China, Russia, Britain and Turkey are either planning to administer or are already administering booster shots.A ‘booster’ is not a new concept in the history of immunology.Additional shots provided to fully vaccinated people after a fixed interval to provide extra protection against diseases like pneumonia have been prevalent, especially in western countries. However, is this really needed for Covid-19, with vaccine supply-demand askew in many parts of the world now? Or, is it a panic-driven demand caused by rise in Delta variant cases?In February, Johnson & Johnson CEO Alex Gorsky had stated that people may need to get vaccinated against Covid-19 annually, just like seasonal flu shots. In April, Pfizer CEO Albert Bourla said people will ‘likely’ need a booster dose within 12 months of getting fully vaccinated, adding, ‘…then from there, there will be an annual revaccination, but all of that needs to be confirmed’. Serum Institute of India (SII) Chairman Cyrus Poonawalla joined in saying that a third, or ‘booster’, dose of Covishield is needed six months after the second dose of the vaccine.Not every expert, however, is buying the (vaccine-sellers’) argument at the moment. Yes, the few trials conducted so far indicate that a third dose of vaccines developed by Moderna, Pfizer-BioNTech, Oxford-AstraZeneca and Sinovac prompted a spike in levels of infection-blocking ‘neutralising’ antibodies when administered several months after the second dose. But the fact is, there is not enough data right now.Large-scale clinical trials are required to study the need and efficacy of booster doses, which is time-consuming. In June, researchers from the Oxford team that developed the AstraZeneca vaccine said that although the third dose of their vaccine can provide a strong boost to the immune response, there was no indication that a booster was needed.According to an August 2021 article published in Nature, it’s certainly difficult to say how long immunity after the Covid-19 vaccination lasts. But as the T cells (a type of white blood cells of the immune system) generated by the vaccines hold up amazingly well, and with 95-99% of Covid hospitalisations being among unvaccinated adults in the US, Covid-19 is now being increasingly described as the ‘pandemic of the unvaccinated’.As Britain prepares for a booster dose drive from September for patients considered at risk of serious illness, the country’s Joint Committee on Vaccination and Immunisation is seeking more data before making a final decision on whether to recommend a booster programme.So, without having enough evidence, are the rich countries gambling with the third dose just to stay one step ahead of the virus? And what about India where universal inoculation is far from near?An August 20 article in the medical journal BMJ pointed out that only 1.3% of people in low-income countries have received at least one dose. Just 32% of the world’s population has had at least one dose, and only 24% have had two. On August 4, the World Health Organisation (WHO) called for a moratorium on boosters, until at least end-September, to enable a minimum of 10% of the population of every country to be vaccinated.So, to boost or not to boost? Will there be a fourth, fifth… dose thereafter? Will the Covid vaccination become a half-yearly or annual event like the flu shot? Very likely.The pharma industry should be happy. While the rich countries may afford annual vaccination for their people, many countries will struggle — and quite a few, simply give up. This could give rise to a new level of global ‘haves’ and ‘have-nots’ wider than any other one before.The writer is professor of statistics, Indian Statistical Institute, Kolkata

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