Is Pfizer Vaccine Effective Against COVID-19 Delta Variant?

The Delta and Delta plus variants, which has emerged as another threat, shifted focus to the effectiveness of vaccines.

Priya Hazra
New Update
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Pfizer vaccine Delta variant: The newly identified Delta variants of COVID-19, classified as the variants of concern, have emerged as another threat. The focus has now, evidently, shifted to the efficacy of vaccines raising concerns about how safe people will be after being vaccinated.

Addressing the concern, Pfizer claimed that its two-dose vaccine remains potent against these new variants. Meanwhile, the American pharmaceutical company is conducting trials on a third dose to test its efficacy for over six months and enhanced immunity in populations.

“We are monitoring trial participants from our landmark Covid-19 vaccine study for two years after their second dose,” said Dr Yasser El Dershaby, Pfizer’s Africa & Middle East Regional Medical Affairs chief.

What is the Delta variant?

Scientists have tracked the variations through genomic sequencing which involves studying the genes of the pathogen. As it is known, viruses evolve and mutate, Sars-Cov-2 coronavirus, too, has mutated into four variants -- Alpha, Beta, Gamma and Delta-- the last being called most transmissible.

The variant is already the most dominant strain in the US and, reportedly, it has contributed to rising cases in India, Nepal, the United Kingdom, Portugal and Australia.

However, as per studies, the vaccines are effective against the Delta variant, but in places where vaccines aren’t widely available or communities that haven’t been able to access them, the possibility of rapid spreading is high.


How effective is the Pfizer vaccine?

Initially, studies showed that Pfizer's vaccine, after two doses, offered 94 per cent protection against early variants. The efficacy rate slipped against the Delta, but it is still good to prevent moderate and serious infections. An analysis by Public Health England showed that vaccines made by Pfizer Inc offer high protection of more than 90% against hospitalization.

On June 25, the central government announced that India is conducting the first-ever study to find the effectiveness of covid-19 vaccines against the Delta plus variant.

The director-general of the Indian Council of Medical Research, Dr Balram Bhargava, said, “The report will be available in 7 to 10 days. India was also the first country to culture Delta variant. Now we are working on Delta Plus, as we have enough information on Alpha, Beta".

Initiative for future variants

According to Khaleej Times, taking measures for later, Pfizer is also studying a booster dose and a prototype vaccine with a ‘variant sequence’ for future strains.


As part of Pfizer’s and BioNTech broad development programme, the safety and immunogenicity of a third dose are being evaluated to understand the effect of a booster on immunity against COVID-19 caused by the circulating and emerging Sars-CoV-2 variants. The Delta plus variant that was found recently in India falls into the category.

Currently, the Pfizer jab needs to be stored in an ultra-cold freezer at temperatures between -80ºC and -60ºC, for not more than six months, however, that might change soon.

“We’re considering multiple areas of continued innovation including formulation improvements potentially through lyophilization (freeze-dried formulation) which we anticipate will be stable under normal refrigeration,” said Dr El Dershaby.

As per reports, Pfizer can deliver approximately 3 billion doses around the world by the end of this year. The company is in discussion with over 125 countries and organisations for supplies.

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