The specialists compared the humoral immune response to the COVID-19 vaccine. The study involved 1,647 health care workers: 688 people were vaccinated with the Moderna vaccine (mean age 43.2 years; 76.7% of women; 21.8% previously infected with coronavirus), and 959 people with the Pfizer vaccine (44.7 years; 84, 9 %, and 13.2%, respectively).
The geometric mean titer of antibodies in those vaccinated with Moderna was 3,836 units/ml, and in those who received Pfizer—1,444 units / ml. Previously infected with coronavirus participants had even higher titer—more than 9,461 units, compared to 1,613 units in those who were not sick.
In both groups, those vaccinated with the Moderna had higher titers when compared to Pfizer:
- previously uninfected—2,881 compared to 1,108 units;
- previously infected—10,708 compared to 8,174 units.
Antibody levels negatively correlated with age in previously uninfected persons , being highest among those younger than 35 years. People of all ages who had previously been uninfected and vaccinated with Moderna had higher titers than those who had been vaccinated with Pfizer.
However, the scientists noted that it is unclear how such differences between vaccines impact their effectiveness, and there is no answer which vaccine is more effective than infection or the course of the disease. Also, such a study does not show how long antibodies remain in the blood.
At the same time, they believe that the difference can be explained by the higher content of the immunogen—mRNA—in the Modrerna dose, as well as by the longer interval between doses—four weeks versus three.
Context. Japan recently recalled a batch of Moderna vaccines produced in Spain. It turned out that some of the vials contained stainless steel. However, the company Takeda that sells the drug in Japan assured that the contained steel particles would not cause an increased medical risk in the case of an injection.
At the same time, Israel reported a decline in Pfizer's efficacy in preventing infection and disease symptoms. Vaccine efficacy has dropped to 64% since early June.