Pfizer Doses More Effective Than AstraZeneca Against The Deadly Delta Variant of COVID-19

Image Credit – Global News


Preliminary observational data suggest that the two doses of the Pfizer-BioNtech vaccine are far more effective against the Delta COVID-19 variant than two doses of the AstraZeneca shot.

A research letter published by The Lancet on Monday evaluated 19543 COVID-19 cases and 377 hospitalizations among 5.4 million people, including 7723 cases and 134 hospitalizations in patients with the Delta variant, who tended to be younger and more affluent.

As per the data, a strong vaccine effect didn’t take hold until 28 days after receiving the second

14 days after receiving the second dose, the researchers found that Pfizer was 92% effective against the Alpha variant which was first identified in the UK., and 79% effective against the Delta variant, which was first identified in India.

Meanwhile, the AstraZeneca vaccine provided 73% protection against the Alpha variant and 60% against the Delta variant.

Dr. Eric Arts, a professor in Western University’s department of microbiology and immunology said that it’s quite a significant difference. After 28 days post-vaccination, he said that there was only really a difference in the protection of about 18% for the AstraZeneca vaccine which is not great.

The Delta variant is greatly expanding throughout Canada.

According to Health Canada, it has accounted for a majority of COVID-19 cases that were identified in March and April. Global News reached out to Health Canada to determine the total count of the Delta variant cases in the country to date but did not immediately hear back.

The variant has also threatened to delay the re-opening plans in the country and also across the

In the UK, Prime Minister Boris Johnson has extended the lockdown by four weeks in an attempt to curb the rapid spread.

Furthermore, the data suggest that the risk of hospitalization amongst those who are infected with the Delta variant has doubled than that of the Aloha variant, especially in respondents with five or more severe medical co-morbidities.

The researchers have found that two doses of both the Pfizer and the AstraZeneca vaccines were effective in reducing the cases of hospitalizations among people who had contracted the Delta strain. But the effectiveness of the shots was diminished when it was compared to those with the Alpha variant.

Chairman of infectious diseases at Queen’s University, Dr. Gerald Evans said that there could be several reasons for this. He told that Delta seems to be a variant that may be causing a more serious form of the disease but it gets very complex, and that’s chiefly because a lot of the people who are getting vaccinated with Delta in the UK are unvaccinated.

However, despite their findings, the researchers have urged to not use the data to compare the vaccines against each other due to other differences in the respondents who have received each type of shot.

Another study says that two doses of either vaccine were more than 90% effective at keeping
the people out of the hospital.


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