The fourth dose of vaccine provides markedly higher antibody levels than the third dose

A team of scientists led by the University of Southampton (UK) followed the study participants, antibody level and their T-cell counts, which are indicators of how protective antibodies are against a person’s SARS-CoV-2 virus.

About 166 people participated in the study and provided blood samples, with which the scientists could check antibody levels in the blood.

Blood samples were examined at various times, including 28 days after the third dose; again at the time just before the injection fourth dose of vaccine (on average over 200 days after the third dose) and 14 days after the fourth dose.

The results showed that antibody levels gradually decreased in the time between the third injection and the fourth dose of vaccine. However, two weeks after the fourth dose, the antibody levels were higher, even significantly higher than those observed after the third dose. Specifically, the study participants had 12 to 16 times higher blood levels of antibodies in the two weeks after they received their fourth injection.

According to the study, which was published in the infectious disease journal The Lancet, this increase was also noted at the cellular level.

The researchers examined data on people who received two doses of the AstraZeneca vaccine, followed by a booster shot with Pfizer’s vaccine, and then received a single dose of Pfizer vaccine or half the dose of Moderna for a fourth dose.

Two weeks after the fourth dose of the COVID-19 vaccine, the antibody levels were higher. (Photo: AP)

At the same time, the scientists also looked at people who had received three doses of Pfizer vaccine, followed by a fourth dose of Pfizer vaccine or a half dose of Moderna.

The CovBoost trial also examined side effects after the fourth injection. No serious side effects were noted in the participants, but some did report pain at the injection site or fatigue.

However, the authors say, the study also suggests that a small number of people may reach a “ceiling” in the level of antibody protection they might get from a fourth dose of the vaccine. Some people have a high degree of immune response “even before the fourth dose and receiving the fourth dose”, including people who have just been infected with COVID-19.

The trial’s leader, Professor Saul Faust, Director of the NIHR Clinical Research Facility Southampton, said: “These results highlight the benefits of a fourth dose of vaccine for vulnerable populations, especially when they received a booster shot this spring and gives confidence to any autumn booster program in the UK, if the Joint Committee on Immunization deems it necessary at that time.” .

Health Secretary Sajid Javid added: “This is further evidence underscoring the importance of getting a booster shot as soon as they are eligible.

We can live with COVID thanks to the protection provided by the COVID-19 vaccine and the booster dose will fortify and increase immunity, thereby continuing to keep you and your loved ones safe. “.

Several groups of people have been encouraged to get a booster shot this spring in the UK, including people aged 75 and over, people living in nursing homes, or those aged 12 and over with weakened immune systems. .

For most people, this will be the fourth dose of the vaccine, but for some people with weakened immune systems, it will be the fifth dose.

More than 3 million people in the UK have received a booster shot so far this spring, according to the UK’s National Health Service (NHS).

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