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Which Vaccine Is Most Effective Against Delta Variant?

Which Vaccine Is Most Effective Against Delta Variant?

Just when we thought we were finally moving forward in our fight against COVID-19, the Delta variant entered the picture. Now, we hear about vaccines losing their effectiveness against the fittest variant and worry about the possibility of needing booster shots. Which vaccine is most effective against the delta variant? To find out, we’ll talk about the vaccines separately.

Which Vaccine Is the Most Effective Against the Delta Variant?


Sinovac is perhaps the most predominant vaccine in the Philippines, but is it effective against the Delta?

Reports say China has not yet released detailed information about Sinovac’s effectiveness against the variant. But, while they didn’t offer data from a large-scale study or real-world scenario, it seems like Sinovac does offer protection.

In Guangdong, where China’s first Delta cases emerged, all severe cases happened to unvaccinated individuals.

Still, booster shots may be necessary as preliminary studies show a “three-fold reduction in neutralizing effect against the Delta.”


Which vaccine is most effective against the delta variant? Is it the Pfizer-BioNtech shot?

The US Food and Drug Administration recently gave Pfizer-Biontech vaccine (now called Corminaty) its full approval. This means Pfizer can now market the jab to people aged 16 and up.

But how well does it perform against the delta?

One study noted that two doses of the Pfizer vaccine offer 96% effectiveness against hospitalization. Please note that you have to complete two doses as there’s also a report claiming that one shot of a two-dose vaccine (like Pfizer and Astra) barely offers any protection.


One report mentioned AstraZeneca showed a significant drop in effectiveness against the delta.

Astra, which is 73% effective against the symptomatic Alpha UK variant, only gives 60% protection when the Delta is involved.

But again, remember that you need to complete two doses.


Which vaccine is most effective against the Delta variant? Will it be the Moderna, which, like Pfizer, is an mRNA vaccine?

A laboratory study revealed that Moderna offers significant protection against the Delta, but it diminished compared to how it protects against the Alpha variant.

In another small study headed by researchers from New York, they discovered that mRNA vaccines, like Pfizer and Moderna, are about 94% to 95% effective against the Delta.

Johnson & Johnson

Unlike the previous vaccines we talked about, Johnson & Johnson COVID vaccine only requires one dose.

In a study, researchers found out that J&J was about 67% effective against severe disease from the Delta.

Another small study involving 20 participants showed that J&J can neutralize the Delta variant 29 days after the jab and that the protection gets better over time.


The Russian vaccine Sputnik, according to authorities, is about 83% effective against the more contagious Delta.


Which vaccine is most effective against the Delta variant?

It’s hard to tell because scientists and health experts are still analyzing the vaccines, and the Delta variant is relatively new.

And while we have all these numbers showing their effectiveness, remember that there are other studies, which might give different results. In other words, the figures here may change depending on factors like the methodology of the studies and who their participants are.

The Only Sure Thing for Now

More than knowing the answer to the question, “Which vaccine is most effective against the Delta variant?”, what’s more important is that you get vaccinated as soon as you can.

Please keep in mind that all vaccines approved by the World Health Organization are safe and effective. They may not prevent COVID-19 infection, but they are 100% effective in preventing severe cases and hospitalizations.

Of course, don’t forget to wear your mask and face shield, practice physical distancing at all times, and perform frequent hand washing.

Learn more about Coronavirus here.

Hello Health Group does not provide medical advice, diagnosis or treatment.


Explainer: Are Chinese COVID-19 shots effective against the Delta variant? https://www.reuters.com/world/china/are-chinese-covid-19-shots-effective-against-delta-variant-2021-06-29/ Accessed September 2, 2021

Vaccines highly effective against hospitalisation from Delta variant, https://www.gov.uk/government/news/vaccines-highly-effective-against-hospitalisation-from-delta-variant, Accessed September 2, 2021

Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization,  https://www.nature.com/articles/s41586-021-03777-9, Accessed September 2, 2021

Covid-19: How effective are vaccines against the delta variant? https://www.bmj.com/content/374/bmj.n1960, Accessed September 2, 2021

Serum Neutralizing Activity of mRNA-1273 against SARS-CoV-2 Variants, https://www.biorxiv.org/content/10.1101/2021.06.28.449914v1, Accessed September 2, 2021

https://www.biorxiv.org/content/10.1101/2021.07.19.452771v1.full.pdf, Accessed September 2, 2021

Durable Humoral and Cellular Immune Responses 8 Months after Ad26.COV2.S Vaccination, https://www.nejm.org/doi/full/10.1056/NEJMc2108829, Accessed September 2, 2021

Russia’s Sputnik V shot around 83% effective against Delta variant, health minister says, https://www.reuters.com/business/healthcare-pharmaceuticals/russias-sputnik-v-shot-around-83-effective-against-delta-variant-health-minister-2021-08-11/, Accessed September 2, 2021


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Written by Lorraine Bunag, R.N. Updated 3 weeks ago
Medically reviewed by Michael Henry Wanat