The fourth dose does not boost immunity? Only one group was included in the study

Israeli researchers tested the effects of the fourth dose of two mRNA vaccines against COVID-19 on health care workers. A fourth dose given to young, healthy health workers may be of marginal benefit, experts say. However, the study did not take into account the elderly.

Scientists from the Israeli Sheba Medical Center Tel Hashomer tested the effects of the fourth dose of two mRNA-based vaccines against SARS-CoV-2 – developed by Pfizer-BioNTech and Moderna.

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154 healthcare professionals were given another dose of Pfizer four months after taking the previous one. A week later, 120 people received the Moderna vaccine.

Fourth dose: effectiveness similar to the third

Both preparations induced the production of anti-SARS-CoV-2 antibodies, raising them to levels slightly higher than after the third dose. Meanwhile, the amount of antibodies in the control group decreased systematically. Both vaccines increased the destruction of the virus to levels similar to those seen after the third dose.

There were no significant adverse effects, although most of the volunteers experienced it mild general and local side effects.

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Fourth dose: how many vaccinated people got infected?

The survey showed that 25 percent. people in the control group were infected with the virus. 18,3 percent were also infected. people after vaccination with a Pfizer preparation and 20,7 percent. those who received the Moderny vaccine.

Most infected subjects – both vaccinated and unvaccinated – reported only mild symptoms.

Most people, due to the high amount of virus in their body, most likely were able to infect others.

During this time, for 100 percent. the case of infections corresponded to the Omikron variant.

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The overall effectiveness of Pfizer’s preparation was estimated by scientists at 30 percent, and Moderny – at 11 percent. When it comes to protection against severe disease, they estimated the effectiveness at 43%, respectively. and 31 percent

“Our data provides evidence that the fourth dose of mRNA vaccines is immune inducing, safe and somewhat effective. Comparing the initial fourth dose response to the peak dose response third did not reveal any clear differences in the humoral response or in the level of antibodies specifically neutralizing the Omikron variant. Although previous data showed an advantage of the third dose over the second dose, our results show that the maximum immunogenicity of mRNA vaccination is reached after three doses, and antibody levels can be restored after the fourth dose, ‘the researchers write.

Researchers point to the low effectiveness of protection against infections observed in medical workers and a high level of virus concentration in the infected.

“A fourth dose given to young healthy health workers may be of marginal benefit. Older (…) people were not included in this study, ”they emphasize.

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