The delta mutation (B.1.617.2) of the coronavirus has spread throughout the world, being a new bet in dealing with the pandemic.
In order to determine the immunity induced by the available approved vaccines of the companies Pfizer and AstraZeneca, a clinical study was conducted to test their effectiveness against delta and alpha strains. The doctors of the Therapeutic Clinic of the Medical School of the National and Kapodistrian Athens, Theodora Psaltopoulou, Panos Malandrakis, Giannis Danasis and Thanos Dimopoulos (Rector of EKPA) summarize these data, as published in the international New England Journal of Medicine.
The efficacy after a single dose of one of the two vaccines was 30.7% against the delta strain and 48.7% for the alpha strain, with similar efficacy for both vaccines.
After two doses of the Pfizer vaccine, the efficacy was 93.7% for the alpha strain, and 88% for the delta strain.
After two doses of the AstraZeneca vaccine, the efficacy was 74.5% for the alpha strain and 67% for the delta strain.
In conclusion, say the professors of EKPA, the effectiveness of the vaccines after two doses and the completion of the vaccination, is great against the symptomatic disease COVID-19, even with the new, more infectious delta strain. They emphasize the urgent need to complete the vaccination of the entire population, especially of vulnerable groups, as long as the delta strain spreads and is expected to prevail in the near future.