An annual boost

Just like the flu shot, Covid-19 booster shots will be required to ramp up the declining or changing immunity, writes Dr Praveen Valsalan

Covid-19 has taught the world a multitude of things. The importance of vaccines comes at the top of it. The introduction of vaccines helped us to breathe a sigh of relief. Now, most people know about what the vaccine is and the need for it. It is a known fact that vaccines have saved millions of lives. But over time, we have seen a lot of breakthrough infections. But most of the breakthrough infections are either mild or have prevented a hospitalisation/requirement for ICU stay or ventilation. Of course, like many other viral infections, Covid-19 vaccines are not 100% effective. Coronaviruses, just like flu viruses, can change their structure, due to mutations in their genetic nature (called variants) and can evade the immunity provided by vaccines, which had caused a lot of concern with the variants having increased transmission rate as well as changing pattern of disease.

WHO has said that “Covid-19 vaccines need to elicit immune responses that are broad, strong and long-lasting to reduce the need for successive booster doses.” Studies have also shown that immunity acquired by the use of vaccines wanes over time. The question which is lingering in our minds is whether a yearly jab, just like the flu shot, is required to ramp up the declining or changing immunity.

A study by the US Department of Veteran Affairs has found that those people who have been vaccinated and got the disease, have a lesser chance of experiencing the long Covid phenomenon. Preventing sniffles is not the aim of taking a jab. But of course, nobody wants to miss their work or school due to a minor infection. But for a vaccine to prevent that will be raising the bar too high.

Fortunately, the current vaccines are doing a good job in what they are supposed to in addressing severe disease, hospitalisation and death. We also have to look into the reinfection and breakthrough infection rates and how many patients will become seriously ill. These viral infections are extremely unpredictable. The pandemic appears to be stable now. But in the coming months, we will know how it will fare, which can give a fairly good idea about the need for the booster dose. We also have to wait and see how these viruses will act during the rainy and winter season. And it is more likely that Covid boosters will also be like a yearly flu jab ritual.

Overall, researchers are not very clear on whether a booster dose every year will be able to provide adequate immunity against these variants. In the absence of very dramatically different strains, it is more likely that the vaccination will become a yearly affair, just like the flu jab.

The updated Covid shots have covered the currently prevailing variants, which means our vaccines have almost caught up with the viruses. But experts are still not sure whether the updated boosters can improve the protection. But the comforting fact is that the fundamental behaviour remains the same. This means that the current vaccines, topped with yearly shots, are enough to protect against the current versions or similar variants of the disease. Many researchers suggest using variant-specific boosters in the coming years just like we give for influenza.

Since the waning of Covid, influenza has started showing its ugly head. There have been a lot of serious cases of influenza with secondary infections. The vaccine companies are already working on developing a combination of influenza and Covid vaccines. The problem these companies are facing is that by the time a new set of vaccines are rolled out, either the new variants will emerge or the spread of the infection in the community will have dramatically reduced.

(The author is a pulmonologist consultant.)