Third Dose of Pfizer Vaccine Increases Antibody Levels ‘Eleven-Fold’

According to preliminary research results, Pfizer and BioNTech, the two vaccine-producing companies, say that administering a third dose of the Pfizer vaccine multiplies the level of blood antibodies against coronavirus many times over, whether against the original virus or against mutated viruses.

The two companies, American Pfizer and German BioNTech, which have jointly developed a vaccine against coronavirus, have announced according to preliminary research results a significant increase in blood antibodies with the administration of a third dose of this vaccine.

On this basis, the level of antibodies against the original coronavirus (“SARS-CoV-2” originating from Wuhan, China) in the blood of volunteers who received the third dose of the Pfizer-BioNTech vaccine increased 5 to 8 times compared to the second dose.

Also, the level of antibodies against the beta mutation of the aforementioned virus (originating from South Africa) increased 15 to 21 times.

Antibodies against the highly transmissible delta mutation (originating from India) increased 5 times in the age group 18 to 55 years and 11 times in volunteers aged 65 to 85 years.

The need for a third dose was raised after it became clear that the effectiveness of the Pfizer vaccine decreases over time.

Based on current knowledge, the effectiveness of this vaccine against the delta mutation, which has caused widespread concern globally, has been reported as 96 percent. However, this level of immunity decreases after 6 months and, according to current information, drops to 84 percent.

Elderly People as First Priority for Third Dose

Nevertheless, the protection that the Pfizer-BioNTech vaccine provides against severe COVID-19 disease remains high six months after the administration of the second dose.

This means that even those who have received two doses of vaccine (are fully vaccinated) are protected against severe disease if they contract the delta variant, and their chances of hospitalization are low.

For this reason, experts have not yet given a clear answer to the question of whether a third dose is necessary, and if so, for whom and when.

Pfizer and BioNTech say there is a possibility that receiving a third dose may be necessary 6 to 12 months after the second dose injection. Of course, this statement only applies to the vaccine of these two companies.

What is certain is that if approval is issued for a third dose, the same group that had priority from the beginning—namely, the elderly and people with underlying diseases—will again be prioritized.

The health minister of Lower Saxony state in Germany announced that this age group, after the end of this summer, can receive the third dose of the Pfizer-BioNTech vaccine if approval is issued.

The manufacturers of this vaccine have submitted a request for approval to the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). To issue this approval, clinical studies must be presented again and the data reviewed.

However, since the original approval was previously issued, it is expected that the decision for third-dose approval will not take long.

Source: DW