Covid, Pfizer vaccine effective after 6 months? What the first data say

Pfizer and BioNTech have released the results of a preliminary study without yet a review on the effectiveness of their Covid vaccine six months after the second dose. The data, published in preprint on medRxiv and not yet peer-reviewed, indicate that in the six months taken into consideration, protection against severe forms of Covid-19 seems to remain very high (97%), confirming the usefulness of the vaccine. in preventing hospitalizations and deaths due to the disease. While, in the same period, in general, the effectiveness of the preparation in preventing contagion seems to go from 96% to 84%. These are the results of a clinical trial, launched last year and concluded in March, conducted on over 44,000 volunteers from six countries. (COVID VACCINE: DATA AND GRAPHICS ON ADMINISTRATIONS IN ITALY, REGION BY REGION)

The data in detail

deepening

The analysis showed that the effectiveness of the vaccine from the US and German Biontech in preventing any Covid-19 infection that causes even minor symptoms seemed to decrease by an average of 6% every two months after administration. Specifically, it appears to remain around 96% in the period between one week and two months after the second dose, and then drop to 90% between two and four months after the second dose, and 84% in the period between four months. and six months. The study did not measure the rate of asymptomatic viral infections and does not provide information on the Delta variant, because the data mostly refer to a period when it was not yet widespread.

Pfizer: the results on the third dose

Yesterday, Pfizer also released the results of trials on the third dose of its original vaccine against the Delta variant. Clinical studies have shown that a further recall “strengthens protection against the Delta variant”. The data “show that a third dose has five times greater neutralizing effects than the Delta variant for those 18 to 55 years after the second dose, and 11 times greater for those 65 to 85 years of age,” Pfizer explained. The authorities, he added, will determine “if and to whom to recommend” a possible third dose.