Third Covid-19 vaccine shot probably not needed after all, research shows
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Third Covid-19 vaccine shot probably not needed after all, research shows

Different coronavirus vaccines by Pfizer/BioNTech, Moderna and AstraZeneca. Credit: Belga

People who have been vaccinated with the Pfizer or Moderna jab will likely not need a third dose of the vaccine after all, according to a new study published in the scientific journal Nature.

The researchers followed up a group of patients for some time after their vaccinations with the Pfizer/BioNTech or Moderna vaccine, and even took biopsies from the lymph nodes in people’s armpits, among other things.

“You are vaccinated in the upper arm, after which your immune system goes into action,” said virologist Johan Neyts of the KU Leuven’s Rega Institute said on Flemish radio on Tuesday. “Some of those immune cells start to nestle in the lymph nodes and train themselves there.”

To make antibodies against the coronavirus, people need so-called b-cells, which then “make the antibodies themselves,” said Neyts.

“In the lymph nodes, [the researchers] have discovered that those b-cells have a great time there and keep training themselves,” he added. “They continue to do so even weeks after the second shot, which suggests that they provide long-term immunity.”

This is very good news, as it means that the vaccines “work much better than expected,” according to Neyts. “Even after two shots, the immune response remains very high for a long time.”

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“They are very safe and now also appear to give very long-lasting protection. From about a week after the second shot, they also protect against the new Delta variant,” he added, referring to the more infectious coronavirus variant first detected in India.

These results may mean that a third booster vaccine dose, to protect against more infectious variants, will not be necessary after all, contrary to what a number of experts have been assuming.

In April, Pfizer’s CEO, Albert Bourla, said that people who received the company’s vaccine would “probably” need a third dose after six months to a year, followed by another shot every year, with the variants in mind.

Additionally, Dirk Ramaekers of Belgium’s Vaccination Taskforce stated that, while it was not yet clear if a third dose was needed, it was already working out the practical details of administering such a shot, likely starting before the end of 2021.

However, the results of the study now indicate that this third shot will not be necessary for most people, according to Neyts. “As an exception maybe, for older people with immune deficiencies, but for the general population, the immune response is strong enough with two shots.”

On Sunday, pharmaceutical company AstraZeneca, whose vaccine was not included in the above study, announced that it was testing a modified version of its jab, which should also protect people against “variants of concern.”

With the modified vaccine, the company aims to “help broaden individuals immune response against emerging variants of concern,” so that it “can be prepared should a variant vaccine be required in the future.”

If the test results are favourable, AstraZeneca plans to have the vaccine approved as an additional booster vaccine.