Does the AstraZeneca vaccine protect against the delta variant of COVID?

astrazeneca vaccine against delta variant
Photo via Marco Verch/Flickr (CC BY 2.0)

With the delta variant quickly becoming the globally dominant strain of the coronavirus, many people are wondering how effective COVID-19 vaccines currently on the market are at combating the disease. The AstraZeneca vaccine, which has already seen an uphill public relations battle due to blood clots and misleading efficacy rates, is likely to be scrutinized more than the others in the fight against the delta variant.

And given that the delta variant, which was first discovered in India, is approximately 60% more transmissible than the original coronavirus, there is clearly cause for concern.

The short answer is that like Pfizer, Moderna, and Johnson & Johnson, the AstraZeneca vaccine has been proven to be effective against serious illness, hospitalization, and death from the delta and kappa variants.

The findings were presented in a scientific study by Oxford University researchers, who examined antibodies from patients who were vaccinated with the two-shot regimens.

“There is no evidence of widespread escape suggesting that the current generation of vaccines will provide protection against the [delta and kappa variants],” concluded the paper, according to Reuters. However, the study found that the concentration of neutralizing antibodies in the blood was “somewhat reduced,” which could lead to possible breakthrough infections.

The Oxford study reinforced an analysis conducted by Public Health England, which likewise found that both the Pfizer and AstraZeneca vaccines offer more than 90% protection against the delta variant. While the Pfizer vaccine was found 96% effective against hospitalization from the delta variant after two doses, AstraZeneca’s vaccine provided 92% protection.

The takeaway here is that even though the delta variant reduces the effectiveness of vaccines against symptomatic infection, two doses of the Pfizer and AstraZeneca vaccines still protect against severe disease.

“We are encouraged to see the non-clinical results published from Oxford and these data, alongside the recent early real-world analysis from Public Health England, provide us with a positive indication that our vaccine can have a significant impact against the delta variant,” AstraZeneca Executive Vice President Mene Pangalos said in a statement.

“This gives us great hope that even as these new variants continue to spread, our vaccine would continue to provide protection for people across the world and help turn the tide of the pandemic for the people of India,” Pangalos added.

Regardless of which vaccine an individual receives, however, the virality of the delta variant underscores the importance of completing the two-shot regimen—with the Johnson & Johnson one-dose vaccine being the exception.

During a June 8 White House press briefing, Dr. Anthony Fauci stressed the importance of vaccinations to prevent the delta variant from becoming the dominant strain in the U.S. As of late June, between 14-20% of new COVID infections in the U.S. were from the delta variant.

“We cannot let that happen,” Fauci said. “To get vaccinated, particularly if you’ve had your first dose, make sure you get that second dose. And for those who have been not vaccinated yet, please get vaccinated.”

Read more on the delta variant: 

Sources: Reuters, ABC News

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