The best results with the Pfizer vaccine
For the analysis that comes from Great Britain, the data of the positives in England for which the virus had been sequenced were used, for a total of about 20 thousand cases of the Delta variant, processed in two different ways. Two doses of Pfizer vaccine were found to be 88% effective in preventing symptomatic disease, compared with 93.7% for Alpha. As for the effectiveness of AstraZeneca, with two doses it was 67%, higher than the 60% reported by other studies, compared to 74.5% for Alfa.
The results confirm that one dose is not enough
The analysis also confirmed that a single dose is not enough: for both vaccines the effectiveness of partial immunization stops at around 30%. “Only modest differences in the efficacy of the vaccine with the delta variant versus alpha were noted after the two doses – the authors write in the conclusions -. The differences are much more marked after receiving a single dose. These data support efforts to maximize the spread of full vaccination among vulnerable populations “.
The Israeli study
Experts from the Israeli Ministry of Health came to a different conclusion, taking into consideration the data relating to infections in the country among people protected with the Pfizer vaccine, the only one used. According to the numbers released, the effectiveness had gone from 94% observed for the other variants to 64% of the Delta, without prejudice to a high level of protection against the most serious forms of the disease and the risk of death.
Data available in Italy
In Italy there are still no specific studies for the Delta variant, but according to the latest data from the Istituto Superiore di Sanità as regards the infection, the complete vaccination course has an effectiveness between 79.8% and 81%, 5%, depending on the age group.
Attention to the duration of antibodies To the problem of efficacy, however, a study published in the Lancet also suggests, that of the duration of the antibodies given by the vaccine could be added. Those generated by the second dose, University college London experts say, begin to decline after a few weeks, and the decline could indicate the need for a booster, at least for the most frail. This was stated by researchers from University College London in a study published in the Lancet journal.