Pfizer losing efficacy faster against Delta variant: Study

NEW DELHI: A new

study

out of the UK has shown that the effectiveness of the Pfizer/BioNTech

vaccine

is waning faster than others when up against a high viral load mutation of the coronavirus, like the

Delta

variant.

The study comes at a time when several countries, including prominent users and early adopters of Pfizer vaccine like the US and Israel, have announced they will be giving out third doses of

Covid

vaccines - or the "booster shots". Since both the US and Israel have been experiencing a rise in new cases of infections, the countries are hoping to increase immunity among those having received a dose of vaccine through the additional shot.

According to a summary of the results of the said, published by The Independent and others, the Pfizer vaccine was 90 per cent effective against high viral load infections one month after the second dose. This declined, however, to 85 per cent after two months and 78 per cent after three months - a loss of 12 percentage points.

The study also looked at the

Oxford/AstraZeneca

vaccine, which is widely used in the UK, Europe and elsewhere. For this vaccine, its effectiveness only declined by 6 percentage points, from 67 per cent to 61 per cent, over the same time period. Despite the fact that the Oxford/AstraZeneca vaccine starts at a much lower initial efficacy, the researchers calculated trajectories that would see the two vaccines at about the same effectiveness after around five months post full vaccination.

The results of the study, which is the largest of its kind to date, have not yet been peer-reviewed. The researchers also noted that despite the declines, both vaccines remained effective at preventing infections by any variant, including Delta, while they were also still very effective at preventing hospitalisation or death in the case of a Covid-19 infection.