AstraZeneca Covid vaccine protection decreases after 3 months: Lancet study

Oxford-Astra Zeneca COVID-19 vaccine protection wanes after 3 months, Lancet study finds

London:

The protection offered by the Oxford-Astra Zeneca COVID-19 vaccine decreases after three months of receiving two doses of the preventive, according to a study published in the journal The Lancet.

Results from the data sets in Brazil and Scotland suggest that booster programs are needed to help maintain protection against serious illness in people vaccinated with AstraZeneca, known as Covishield in India.

The researchers analyzed data from two million people in Scotland and 42 million people in Brazil who had been vaccinated with the AstraZeneca vaccine.

In Scotland, compared to two weeks after receiving a second dose, the risk of being hospitalized or dying from COVID-19 was around five times higher almost five months after being doubly vaccinated, researchers said.

The drop in efficacy begins to appear around three months, when the risk of hospitalization and death is double that of two weeks after the second dose, they said.

Researchers in Scotland and Brazil found that the risk of hospitalization and death increased threefold within four months after the second dose of the vaccine. Similar figures were seen for Brazil, they said.

“Vaccines have been a key tool in the fight against the pandemic, but declining effectiveness has been a concern for some time,” said Professor Aziz Sheikh, University of Edinburgh, UK.

“By identifying when the decline begins to occur in the Oxford-AstraZeneca vaccine, it should be possible for governments to design booster programs that can ensure maximum protection is maintained,” Sheikh said.

The team was able to compare the data between Scotland and Brazil as they had a similar interval between doses – 12 weeks – and the initial prioritization of those vaccinated – those most at risk of serious illness and workers in the health.

The dominant variant was different in each country during the study period – Delta in Scotland and Gamma in Brazil.

This means that the drop in efficacy is likely due to the shrinking vaccine and the impact of the variants, the researchers said.

The study also estimated the vaccine’s effectiveness at similar two-week intervals by comparing the results of people who were bitten with those who were not vaccinated.

However, experts have warned that these numbers should be treated with caution as it becomes increasingly difficult to compare unvaccinated people with those vaccinated with similar characteristics, especially among older groups where so many are now vaccinated. .

“Our analyzes of national datasets from Scotland and Brazil suggest that there is a considerable decrease in the efficacy of the Oxford AstraZeneca vaccine, with protection against severe COVID-19 diminishing over time,” said Professor Srinivasa Vittal Katikireddi of the University of Glasgow in the United Kingdom. .

“Our work highlights the importance of getting boosters, even if you have received two doses of the Oxford AstraZeneca vaccine, as soon as you can,” added Srinivasa Katikiredd.

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