One shot of Pfizer, AstraZeneca vaccine 'barely' work against 'Delta' covid variants: Study

Washington, July 09: A new study has found that a single shot of Pfizer-BioNTech or AstraZeneca vaccines for Covid-19 "barely" work against the Delta variant of the deadly virus, because of mutations the variant has developed.

The study, published in the journal Nature, highlighted the threat posed by viral mutations of coronavirus disease (Covid-19) as the Delta variant is rapidly becoming the dominant strain across the world.

The team of French researchers tested how efficiently antibodies produced through natural infections or vaccines neutralized variants of the coronavirus, including Delta, which was first identified in India.

They discovered that the Delta variant has developed mutations to cell entry mechanisms that allow it to evade certain antibodies.

While one dose of Pfizer's or AstraZeneca's vaccines was less effective at neutralizing the variant compared to two, it still performed better than the antibodies produced through natural infection, suggesting that people who contracted the virus may still need vaccine to help defend against variants.

But weeks after getting their second dose, nearly all had what researchers deemed an immune boost strong enough to neutralize the delta variant - even if it was a little less potent than against earlier versions of the virus.

Highlighting the importance of full vaccination against COVID-19, the study also revealed that fully vaccinated individuals of Pfizer-BioNtech or AstraZeneca vaccine are well protected and retain significant protection against the highly contagious Delta variant.

The lab experiments add to real-world data that the delta variant's mutations aren't evading the vaccines most widely used in Western countries, but underscore that it's crucial to get more of the world immunized before the virus evolves even more.