The Centers for Disease Control and Prevention (CDC) earlier in August approved administering COVID-19 booster shots to Pfizer and Moderna vaccine recipients, endorsing third doses for immunocompromised Americans.
“At a time when the Delta variant is surging, an additional vaccine dose for some people with weakened immune systems could help prevent serious and possibly life-threatening COVID-19 cases within this population,” CDC Director Dr Rochelle Walensky said in a statement.
Are two vaccine doses enough to fight the coronavirus? Do they protect you against all variants? Here's all you need to know.
What is a booster shot?
A booster shot is the one that is given to strengthen one's immune system against a particular pathogen. When the first shot of COVID-19 is given, it only primes your immune system – that is, it sensitises it to the foreign object.
Only the second dose strengthens the immune system, producing more antibodies and protecting you from a severe form of the disease.
What has the Centre and AIIMS Director said?
“No specific recommendation regarding Covid-19 vaccine booster dose has been made by National Technical Advisory Group on Immunization (NTAGI) and National Expert Group on vaccine administration for Covid (NEGVAC). There are at present no recommendations on booster dose from World Health Organization,” the MoS Health Bharti Pravin Pawar responded to a question in the Rajya Sabha.
However, Guleria recently said that India could need booster shots and that trials are underway.
"It seems that we probably will need the booster dose of vaccines as with the passage of time the immunity tends to fall. There is waning immunity. We would like to have booster dose that will cover for various emerging variants,” Guleria told news agency ANI.
What are the benefits of a booster shot?
Research has shown that booster shots train your body to detect and protect viruses or bacteria. Depending on the type and manufacturer of the vaccine, you may get booster shots, weeks, months or even years after your first shot, FIT explained.
The booster dose can activate the immune system immediately. It works on the basis of 'immunological memory' where the immune system remembers the vaccine that the body has already used. In such a situation, the booster dose activates the immune system immediately, whose effect is seen more, FIT report said.
In an interview to The Economic Times, Dr Giridhar R Babu, Professor and Head of Life Course Epidemiology at the Public Health Foundation of India, stated that 'depending on how long the vaccine protection lasts, one needs to decide when to give the booster. But it still needs to be seen and studied whether the boosters will help in fighting the disease more effectively'.
Why are we talking about the need for booster shot?
Mainly because of the Delta variant. While vaccine manufacturers maintain that vaccines are effective against the variant, initial studies show that some variants are breaking down the protection.
For example, Delta mutation brings down the effectiveness of mRNA shots from BioNTech SE and Moderna less effective – bringing down protection to below 90 percent. The Oxford-AstraZeneca vaccine, provided in India as Covishield, is showed lower effectiveness at 60 percent, a study showed.
Will we really need a third dose for better protection?
We do not know yet. The World Health Organization (WHO) is yet to approve booster shots.
WHO Chief scientist Soumya Swaminathan sounded a warning in June, adding that the recommendation was 'unnecessary and premature' given the lack of data.
In a conversation with FIT, virologist Dr Shahid Jameel explains, “Right now, the COVID vaccine has been tested in a two-dose trial. Further doses may be needed, but a study should be done to prove this. However, booster dose is not required so soon. Immunology also does not say that. It is of no use to take booster doses so soon.”
“The third dose does not affect the memory response or secondary response. But, after 2-5 years, it can consolidate the decreasing memory response.”Virologist Dr Shahid Jameel to FIT
Who is most likely to need a booster shot?
First, booster shot is only for people who have already received their two complete doses of vaccine. In most countries, more than half the population is yet to receive even a single dose of vaccine.
Booster shot will be more helpful for the elderly and the immunocompromised, whose bodies would have produced relatively lesser antibodies from the first two shots.
If studies show that a new variant is resistant to the vaccine, then all those who have taken the particular vaccine will be required to take the booster shot.
What are vaccine manufacturers saying?
Pfizer and BioNTech, earlier in June, said that they have designed a version of their vaccine specifically to combat Delta variant.
Pfizer CEO Albert Bourla tweeted that the company believes a booster dose 'will likely be necessary to maintain highest levels of protection' against COVID, adding that data from its booster study demonstrating that the added dose was eliciting 5 to 10-fold higher antibody response.
According to the BBC, the UK government is urging the working age group and people over 75 years to participate in the third dose trial to study its efficacy in defending new COVID variants.
COV-Boost vaccine trial is studying the use of seven different COVID-19 vaccines when given as a third dose.
According to the report, Professor Saul Faust, Chief Investigator at Southampton University, says that it is possible that some age groups may not need boosters and some may.
He also said, "We are not trying to say that one vaccine is better than the other. Its purpose is to find out what should be a booster campaign and which vaccine should be used.”
Which countries have started administering booster shots?
Like Israel, many Middle Eastern countries including Bahrain, are already offering booster shots to those who had completed their vaccination earlier. Indonesian Doctors Association has called for the government to green light booster shot, especially for health workers.
Media reports suggest that Thailand is also considering giving booster shot for frontline workers.
What is happening in India?
In India, Bharat Biotech's Covaxin is undergoing trials for booster shot. However, the company has said that results will come only in November 2021. Watch out this space for more information.
(With inputs from FIT)
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