Study finds 2 doses of Pfizer, AstraZeneca effective against Delta strain

A study published yesterday shows that 2 doses of the Pfizer vaccine or 2 doses of the AstraZeneca vaccine are almost as effective against the rapid-spreading Delta variant as they are against the Alpha variant. In Thailand, the AstraZeneca vaccine is being produced locally and is the primary vaccine being used in the nationwide Covid-19 immunisation campaign.

Thailand recently approved the use of the AstraZeneca vaccine as a third “booster” shot as well as a second dose for those who received a dose of the Sinovac vaccine. The AstraZeneca is said to be more effective against the highly transmissible Delta variant which is now on the rise in Thailand.

According to the study published in the New England Journal of Medicine, the Pfizer and AstraZeneca vaccines are nearly just as effective against the Delta variant as it is the Alpha variant. The study also reiterated that a single dose of either the Pfizer or AstraZeneca vaccine is not enough to offer high protection against the virus.

“Only modest differences in vaccine effectiveness were noted with the Delta variant as compared with the Alpha variant after the receipt of 2 vaccine doses.”

The findings…

• 2 doses of the Pfizer vaccine were 88% effective against the Delta variant.
• 2 doses of the Pfizer vaccine were 93.7% effective against the Alpha variant.
• 2 doses of the AstraZeneca vaccine were 67% effective against the Delta variant. It was originally reported that the 2 doses of vaccine were up from 60% effective against the mutated strain.
• 2 doses of the AstraZeneca vaccine were 74.5% effective against the Alpha variant. The original estimate was that it had a 66% effectiveness against the variant.
• A single dose of the Pfizer vaccine was 36% effective against the Delta variant and a single dose of AstraZeneca was 30% effective. Previous reports from Public Health England said the first dose of either vaccine was about 33% effective against the Delta variant.

“Our finding of reduced effectiveness after the first dose would support efforts to maximise vaccine uptake with two doses among vulnerable groups in the context of circulation of the Delta variant.”

SOURCE: Reuters