How Effective Are COVID-19 Vaccines Against Delta Variant? What Data Says

Questions of vaccine efficacy against Delta variant of COVID-19 have spurred angst anew, even as the pace of infections slows down across the world.

First identified in India, the Delta strain of the SARS-CoV2 virus and its mutated variant Delta Plus could well become the dominant health concern if not contained, experts are warning. Since research into the variants is still underway, a question mark looms over the efficacy of COVID-19 vaccines against them.

"The so-called Delta Plus variant exhibits an additional mutation in the Delta variant and since this is a new variant, scientific knowledge is still in the early stage," Dr VK Paul, who is leading India's COVID-19 vaccine task force, told PTI Monday. He said there is no data yet to ascertain if the severity of the disease will affect vaccines adversely. 

Citing Indian Council of Medical Research (ICMR) evaluations, Dr Paul said Covishield and Covaxin - two vaccines in the Indian market - are both effective against the Delta variants.

Developers of Sputnik V in Russia claimed Tuesday that the vaccine is 90 percent effective against the Delta variant, Reuters reports. In India, Sputnik V manufactured by Dr Reddy's is the third vaccine to be made available, however commercial rollout is yet to become mainstream.

Understood as the variant that drove coronavirus infections during the deadly second wave in India, Delta has now been identified in at least 85 countries, as per reports.

The World Health Organisation (WHO) which gave the variant its 'Delta' name has deemed it "the most transmissible of the variants identified so far" and has classified it as a variant of concern (VOC).

WHO has urged even fully vaccinated adults to "play it safe" and keep COVID-19 protocol - masking, sanitising, social distancing - up as variants emerge. "This still continues to be extremely important, even if you’re vaccinated when you have a community transmission ongoing," a spokesperson said from the Geneva headquarters.

Vaccine Efficacy Against Delta Variant? Solid Research Awaited

Though universal word on vaccine efficacy against Delta variant is in the shadows, there is ample medical observation that shows this VOC is more virulent, transmits faster, poses more serious health risks, can lead to greater hospitalisations, and affects young persons severely.

Countries like the United Kingdom and the United States have said the Delta variant is a bigger concern than Alpha (B.1.1.7 lineage) that was detected in the UK last year, spreading to other European countries and North America greatly.

UK's health authority Public Health England has said over 90 percent of samples being sequenced in the country are of the Delta variant, and new cases are climbing in count despite 80 percent of their adult population being vaccinated. PHE data last Friday indicated that out of the 117 people who died from the Delta variant, 50 were fully vaccinated.

Experts have, however, said the efficacy of vaccines - Pfizer and AstraZeneca for the UK - should not be called into question since the factor of age is a big decider and that "it’s what we would expect from an effective but imperfect vaccine."

New research published Monday by the Washington University in St Louis meanwhile suggests the Pfizer vaccine may offer protection from COVID-19 for years to come, without the need for booster jabs. An Oxford study, also published recently, has found a third AstraZeneca dose could boost efficacy.

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