The Delta variant of COVID-19, now circulating in more than 111 countries, is soon expected to become the dominant COVID strain worldwide. COVID-19 vaccination, and COVID-appropriate behaviour like masking and distancing are viable solutions to check the spread of the virus.

Here is a look at the best COVID-19 vaccines that are working against the Delta variant. Vaccines by Pfizer-BioNTech, Moderna and AstraZeneca underwent clinical trials when the Delta variant was non-existent, but now we have real world evidence to tell us how the leading jabs are working against the variant.

Pfizer-BioNTech

The Pfizer-BioNTech mRNA vaccine, which is widely used, does give some protection against a symptomatic infection with the Delta variant, but at a reduced efficacy. The Pfizer jab’s original efficacy was 95.3 percent against symptomatic infections and 100 percent effective against severe COVID-19 disease and hospitalisation.

A single dose of Pfizer-BioNTech vaccine gave 56 percent efficacy in Canada, and 33 percent efficacy in UK.

COVID-19 Vaccine

Frequently Asked Questions

How does a vaccine work?

A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

How many types of vaccines are there?

There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

What does it take to develop a vaccine of this kind?

Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.

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Here is what real world evidence says about efficacy of COVID-19 vaccines against Delta variant

Pfizer-BioNTech, Moderna and AstraZeneca vaccines underwent clinical trials when Delta variant didn't exist.

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