The third jab: Are booster shots of Covid-19 vaccine necessary? Experts answer

The global debate over booster shots is gradually becoming a complicated affair. Even as vaccination drives gain momentum all over the world, Covid-19 variants and breakthrough infections are a bigger concern. This leaves us with an imminent question of whether two doses of vaccines are enough or do we need a third shot.

A booster dose refers to another dose of a vaccine given to someone to build enough protection after vaccination, but then that protection can decrease over time. Those who are moderately to severely immunocompromised do not build enough protection in the first vaccination, and a second dose can help build more protection against the disease, say the Centers for Disease Control and Prevention (CDC).

Scientists and experts feel the priority must be to ensure that more people are inoculated with at least one jab. Indian Council of Medical Research (ICMR) Director General Balram Bhargava said in a news report that a booster dose is not the central theme at the moment and getting two doses remains the major priority.

But the CDC recommends moderately to severely immunocompromised people consider receiving an additional (third) dose of an mRNA Covid-19 vaccine (Pfizer-BioNTech or Moderna) at least 28 days after the completion of the initial 2-dose mRNA Covid-19 vaccine series. The CDC says the goal is for people to start receiving a booster shot with individuals being eligible starting eight months after they received their second dose of an mRNA vaccine. Additionally, US top infectious disease expert Dr Anthony Fauci feels booster shots can become necessary to gain maximum protection against Covid-19.

However, the reasons for booster doses may differ by population groups at risk, type of vaccine, waning immunity, variants of concern, and clinical and epidemiological settings. “For many diseases, booster shots are needed from time to time. In the case of Covid-19, it has become a matter of debate. Right now, there is uncertainty about the booster dose but maybe it would be needed in the times to come. Studies show that immunity after Covid vaccine wanes in a few months’ time and hence the need for a booster dose. As and when other variants emerge that are going to be worse than the present Covid-19 variants and has the potency to evade the currently available vaccines, then the requirement of booster shots would be needed,” says Dr Suranjit Chatterjee, senior consultant, internal medicine, Indraprastha Apollo Hospitals, Delhi.

Agrees Dr Mrinal Sircar, director and head, pulmonology and critical care, Fortis Hospital Noida, “A third dose of vaccine would be required to sustain the much-needed protection from the virus and reduce the severity, most importantly to those above the age of 60 or with compromised immunity.”

Despite all this, the World Health Organization strongly opposes the widespread rollout of booster shots; instead, rich nations must give extra doses to countries with minimal vaccination rates. The Lancet study has published a review of vaccine efficacy is so high that booster dose for the general population is ‘not appropriate’ at this stage.

In a recent development, an advisory panel to the FDA has offered a limited use of booster shots of the Covid-19 vaccine from Pfizer and BioNTech, recommending injections for people 65 and older or at high risk of severe disease but stopping short of justifying them for the broader population.

On the other hand, Johnson & Johnson’s new announcement in September promoted strong response to booster shots. In a data report submitted to the FDA and other regulatory agencies on when a booster was given six months after the first shot, the company says, “antibody levels increased nine-fold one week after the booster and continued to climb to 12-fold higher four weeks after the booster,” irrespective of age.

Such claims have made experts feel the need for a third booster depends on how much one’s body is vulnerable to infection and the requirement of booster shot entirely depends on the mutations of the variants.

“The requirement may differ and depend on whether the currently available vaccines are potentially effective in covering the emerging variants that can be even more serious than the current ones,” says Dr Rajesh Chawla, senior consultant pulmonology and critical care, Indraprastha Apollo Hospitals, Delhi.

Globally, many countries like Israel, the UAE, Russia, France, Germany and Italy have already rolled out boosters. Israel approved a booster dose of the Pfizer vaccine for 60 and above, Britain’s Covid booster rolled out in September with the first extra doses given to health workers.