With the reproduction rate of the novel coronavirus rising in some states in the wake of Deepavali, public attention is once again riveted on getting a vaccine booster shot. The demand is not uncommon. Several countries have already approved a booster dose and preliminary studies show that a third shot is effective in reducing the effects of Covid-19. India, however, could take longer to approve such a dose. Here's the lowdown on booster shots:
What is a booster shot?
The aim of a booster shot is to restore the protection levels of earlier vaccination doses in the body to ensure overall effectiveness against the novel coronavirus.
How many countries are offering booster shots?
Thirty-six countries have approved booster doses. The US is dispensing an average of 3.2 lakh booster doses a day. While the World Health Organization (WHO) has criticised the deployment of booster doses because worldwide vaccine coverage has remained low in poor countries, some countries say they are necessary to combat a renewed surge in Covid-19 infections. Among them is Singapore (where 88 per cent of the population has received two doses) and the UK (79 per cent). The latter has been suffering a surge of infections since mid-September.
What about India?
The Indian Council of Medical Research (ICMR) has not yet approved a booster shot although there are anecdotal reports of medical staff and private citizens secretly getting a third shot. In Karnataka, health officials say there is no evidence of booster shots being taken secretly. Dr Arundhathi Chandrashekar, Director of the National Health Mission, who also oversees the state’s vaccination programme, says the Technical Advisory Committee has not yet recommended a booster shot for interested members of the public. "Our focus is on completing the second dose — only then can we consider introducing a booster," she told DH.
What is India’s vaccination status at the moment?
As per official data, India achieved 53 per cent first dose coverage as of Sunday evening, and 24.5 per cent second dose coverage as of Saturday. Projections indicate that India will cross 80 per cent second dose coverage only in 2022.
How effective have vaccinations been in preventing hospitalisations?
That depends on age and risk factors from comorbidities. In Bengaluru Urban, for example, between 15 October and 1 November, out of 12 people hospitalised for Covid-19 in the ICU, six were fully vaccinated and four were not vaccinated. Among six people admitted into an ICU-Ventilator, four were not vaccinated. Officials also note that most hospitalisations of vaccinated individuals happen 100 days after the second dose. "The bottom line is that even fully vaccinated people should follow all Covid-19 protocols,” says Dr K V Thrilok Chandra, Special Commissioner (Health), BBMP.
Have there been deaths among people with two doses in India?
According to the ICMR, the death rate of fully vaccinated people is 0.05 per cent.
What is the duration of protection from two doses of the vaccine?
Epidemiologist and public health expert, Dr Chandrakant Lahariya, says that “going by current evidence, we can say that a person is very likely to be protected for one year minimum.”
At the same time, the fact that this vaccination is happening at a time of infection could mean that immunity could last longer than a year, he notes. The counterpoint is that a "majority of respiratory viruses already known to humankind require a booster shot," he adds.
Is there any other data about the decline of vaccine efficacy?
In the US, out of a survey of breakthrough infections from the Delta variant among 6.2 lakh military veterans, the Pfizer vaccine's efficacy was found to decline from 91 per cent to 52 per cent over six months, while the Moderna vaccine's declined from 92 per cent to 64 per cent. This prompted Israel to decide that a third vaccine dose would be needed for people who have received two vaccine doses at least five months ago.
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