The delta strain (B.1.617.2) of the SARS-CoV-2 virus has spread worldwide, which is a new topic in the fight against the pandemic. To determine the immunity caused by approved vaccines from Pfizer and AstraZeneca, a clinical study was conducted to test their effectiveness against the delta and alpha strains that are currently in use.
Doctors of the clinics Θεραπευτικής Κλινικής της Ιατρικής Σχολής του Εθνικού και Καποδιστριακού Αθηνών Theodora Psaltopoulou, Panos Rekandrakis, Yannis Delta mutations “and published in the international medical journal” New England Journal of Medicine “.
How Vaccines Protect Against Delta and Alpha Strains
The efficacy after one dose of one of the two vaccines was 30.7% for the delta strain and 48.7% for the alpha strain, with similar efficacy for both vaccines.
After two doses of 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 only 67% for the delta strain.
In conclusion, it should be noted that the effectiveness of the drugs after two doses and completion of vaccination is great against the symptomatic disease COVID-19, even against the new, more infectious strain of delta.
It is worth noting, of course, that they are slightly less potent on the delta strain than the alpha strain. As epidemiologists emphasize, this indicates an urgent need to complete the vaccination of the entire population, especially vulnerable groups, as the delta variant spreads and is expected to prevail in the near future.