What are the side effects of the third dose of the Covid vaccine?

The hypothesis of offering the entire adult population The third dose of the Anti Covid vaccine is increasingly likely. For now in Italy the reinforcement, wi

What are the side effects of the third dose of the Covid vaccine?

The hypothesis of offering the entire adult population The third dose of the Anti Covid vaccine is increasingly likely. For now in Italy the reinforcement, with MRNA vaccines, is reserved, in order of priority, for immunosuppressed people, over 80, residents in residences, health personnel, over 60 and people with previous pathologies. Ilaria Capua, Director of the UF One Health Center at the University of Florida, who has also received the reinforcement vaccine, says: "People who will now be vaccinated, know that they can do it."

Therefore, even after the third dose, mild discomfort may be presented. In fact, according to the data published on October 1 by the Ministry of Israeli Health, the effects are "significantly lighter" than those of the first two injections.

The most common symptom is general fatigue, detected in 86.6 people per million compared to 271.8 and 251.1 per million after the second and first dose, respectively. Pain in the vaccination zone affected 42.7 people per million in the third dose, compared to 222.9 and 514.3 in the second and first.

The data refers to approximately three million that have received the reinforcement dose. There were only 19 serious disorders but the possible link with the vaccine is still being evaluated. The Israeli Ministry of Sanida affirms that "side effects were found after the third dose in a small percentage of adults of 60 years or more and are consistent with those observed after the first two doses or other vaccines; generally include pain in place of injection, headache, fever, chills, muscle pain ".

The US centers for the control and prevention of diseases (CDC) also examined the side effects of the third dose of the vaccine and concluded, in a report published on September 28, which are similar to those observed after the other doses. The experts of the CDC say that the adverse symptoms are mostly moderate or mild and do not last long.

As with the first doses, the symptoms appeared within 48 hours after vaccination. The analysis was carried out in more than 2,200,000 Americans who had received the third dose until September 19. About 22,000 responded voluntarily to a questionnaire: 28% had problems the next day of vaccination. The most frequent symptom was the pain in the arm, warned in 71% of the cases. 56% reported fatigue, 43.4% reported headaches. 7% had severe pain. 2% needed medical assistance and 13 people were hospitalized.

The percentages are in line with those corresponding to the second dose of vaccine. There is still no data on the risk of myocarditis and pericarditis after the third dose, also because at the moment the reinforcement has been offered only to the older groups (in the US over 65 years and people with previous pathologies) , while the cardiac problems after the vaccine (very rare and non-severe) have mainly affected young people.

According to several studies, the effectiveness of vaccines begins to decline between 6 and 9 months after the last injection. But for immunosuppressed people, protection fails long before. That is why a distinction was made between "third dose" and the "reinforcement": the third dose can be administered 28 days after the second and is intended to complete the vaccination cycle in people who have not responded effectively to the first two injections. The reinforcement, on the other hand, can be carried out from the 6 months after the second dose and aims to reactivate the production of antibodies.

In fact, according to a study published in the last days in the New England Journal of Medicine, the efficacy of the third dose of Pfizer is 95.6%, with 5 cases of infection in the vaccinated group, compared to 109 infections in the Placebo group. The results of the trial were presented to the Advisory Committee of the US Food and Medicines Administration (FDA) and it was found that neutralizing antibodies were high against all variants, including beta and delta.

In addition, the maximum efficiency of the third dose is reached at 7 days. A fifth of the participants of the study were more than 65 years old, a category with a higher risk of severe Covid.

Effectiveness numbers refer to the contagion: the capacity of vaccines to combat deaths and hospitalizations is greater than 90% (and close to 100%) in each analysis even with only two doses of vaccine, but protection against infections weakens After 6 months, especially in the most exposed categories, so the third dose is useful.

Recently, the European Medicines Agency (EMA) gave green light to the administration of the third dose of the modern vaccine (Spikevax) in people over 18 years of age. For the souvenir dose (which must be carried out between 6 and 8 months after the second dose), it is enough with half dose.

The data available, says EMA, indicate that the risks of side effects after the third dose are similar to those observed after the second.

Previously, the agency had already given green light for the administration of the third dose of the Pfizer-Biontech (Comirnaty) vaccine for those over 18, six months after the second dose. In addition, EMA stressed that a third dose of both vaccines can be administered with serious deficiencies of the immune system 28 days after the second.

Updated Date: 07 November 2021, 18:45

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