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Third time is the charm with Covid shot, says study

Third time is the charm with Covid shot, says study

UK study says booster vaccine leads to a tenfold increase in antibody levels
UK study says a booster Covid shot leads to a tenfold increase in antibody levels
A nurse inoculates a youth with a booster dose of the Pfizer vaccine against Covid-19 in Mexico City, on February 9, 2022. (Photo by CLAUDIO CRUZ / AFP)

The Covid-19 booster vaccine dose — or the third Covid jab — has been found to generate more antibodies for everyone, especially for vulnerable people like the elderly and those who are immunocompromised.

Researchers in the UK have found that the level of antibodies produced after the booster was about 10 times higher in the first week compared to the levels found in people who had taken the second shot about six months ago. The study, published in eLife on January 24, indicates that the third vaccination shot also ensured that vulnerable people have antibody levels equivalent to that of healthy individuals.

In an online interaction with Happiest Health, Prof Dr Claire Steves, department of twin research and genetic epidemiology, King’s College London and joint senior author of the study, says that the findings confirms that the booster vaccine offers better protection against Covid infection — to a greater extent than the first two vaccine doses.

“Yes, we found that booster vaccination lifted (increased antibody level for) those who didn’t respond so well after two vaccinations,” she says. Prof Steves adds that almost everyone involved in the study had a robust response which will further reduce the risk of infection.

A team of researchers from the University of Bristol, King’s College London, University College London and several other institutions around the UK are part of the National Core Study for Longitudinal Health and Wellbeing, which was set up in October 2020 as part of the country’s response to the pandemic.

Booster shot is a Covid antibody equaliser

According to the official release from the University of Bristol, the study has found that the third dose eliminated the disparity in antibody levels in the different versions of the mRNA Covid vaccines. The results indicate that though initially those who received the Oxford/AstraZeneca vaccine were found to be with lesser antibodies when compared with those who opted for the Pfizer- BioNTech after the first two doses, the third booster has levelled this difference.

“Our findings support a policy of a third (and now fourth) COVID-19 vaccination to boost antibodies and protect against COVID-19. This is especially true for people who had the Oxford/AstraZeneca vaccine for their first and second jabs,” first author of the study Dr Natham Cheetham from King’s College London says in an official release.

Asked whether adenovirus-based vaccines produced lesser antibodies and why, Prof Steves explains to Happiest Health that adenovirus antibody levels were not included in the scope of the study. “But the fact is after a booster with an mRNA vaccine, it didn’t seem to matter what vaccine the person received for their first dose as the booster levelled out that difference as well,” she says. The Covid jab rolled out by Johnson & Johnson is an adenovirus vaccine.

As part of the study, researchers analysed over 9,000 blood samples from participants of the Children of the 90s and Twins UK cohorts, two of the largest UK population cohort studies in the UK to arrive at these conclusions.

“It is fascinating to observe the dynamics of immune response and of course it is reassuring to see how effective the booster jabs are,” Prof Nic Timpson, principal investigator of Children of the 90s and joint senior author, says in the release.

Good antibody response among the vulnerable, shielded people

The United Kingdom had adopted an elaborate Covid response in which people diagnosed with immune deficiencies and vulnerable comorbidities, including diabetes, were classified as Clinically Extremely Vulnerable (CEV) categories and were asked to stay put inside their homes during the initial phase of the pandemic (from 2020 to 2021). This strategy was officially called shielding and the Covid response of the UK’s public health department was primarily focused on this shielding programme.

The study has revealed even the people under the shielding programme, despite having low antibody response from the initial rounds of vaccination, had much better levels of antibodies after the booster shot.

“In the UK we had a list of people who needed to shield. We saw that this group as a whole had reduced antibody response to initial vaccination. The good news was that this too levelled up with the booster,” Prof Steves says. She adds that one of the indicators of weaker response to these vaccines was frailty.

“That (frailty) is the cumulative health problems a person has. We already know this is related to changes in the immune and inflammatory system, and this is further confirmation of that,” she says.

Dr T Jacob John, public health expert and retired head of department, clinical virology, Christian Medical College, Vellore, Tamil Nadu, also points out the need to boost immunity, especially for vulnerable people.

“Coronavirus will be with us,” he says. “It will not be fatal for everyone, but it could cause serious health complications for vulnerable people. There are many things that we must do to keep our immunity strong, and one of them is to get the booster dose this year.”


The third booster dose was found to produce 10 times more antibodies in the initial weeks when compared to the antibody levels after the first and second doses of the mRNA vaccine. The results of the study are expected to help policymakers and people to make an informed decision as part of the collective response against Covid.

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