A new scientific analysis, published by Public Health England, has found that two doses of Covid-19 vaccines are highly effective in preventing hospitalisation due to B.1.617.2, now known as the Delta variant. Importantly, it showed no deaths among those vaccinated.
The analysis gives effectiveness data of two vaccines. Pfizer-BioNTech’s mRNA vaccine was found 96% effective in preventing hospitalisation after two doses. The Oxford-AstraZeneca vaccine was found 92% effective after two doses. The Indian version of this vaccine, Covishield from Serum Institute, is among the vaccines being administered in the country.
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How was the analysis conducted?
Researchers from the London School of Hygiene and Tropical Medicine, London and Guys, and St Thomas’s Hospital NHS Trust, London, linked all symptomatic Covid-19 cases between April 12 and June 4 to the Emergency Care Dataset (ECDS) which records all admission via emergency departments in England. The analysis included 14,019 cases of the Delta variant – 166 of whom were hospitalised.
The analysis showed that the vaccines’ effectiveness in preventing hospitalisation with Delta was similar to that seen with Alpha — (94%) after the first dose and 96% after the second dose of the Pfizer vaccine; and 71% after the first dose and 92% after the second dose of the Oxford-AstraZeneca vaccine.
“These findings indicate very high levels of protection against hospitalisation with the Delta variant with 1 or 2 doses of either vaccine,” the researchers concluded in the paper, which is yet to be peer-reviewed.
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What are the takeaways?
Matt Hancock, Health and Social Care Secretary, said it is vital to get both doses as soon as they are offered to you, to gain maximum protection against all existing and emerging variants.
On Tuesday, AstraZeneca said that real-world data from PHE suggest that vaccine effectiveness against milder symptomatic disease, although significant, was lower — 74% against the Alpha variant and 64% against the Delta variant. “The higher efficacy against severe disease and hospitalisation is supported by recent data showing strong T-cell response to Covid-19 Vaccine AstraZeneca, which should correlate with high and durable protection,” AstraZeneca said.
The data also suggests that Covishield, which accounts for 88% of doses being given in India, will have a significant impact in reducing hospitalisation in the country.
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“This real-world evidence shows that COVID-19 Vaccine AstraZeneca provides a high level of protection against the Delta variant, which is currently a critical area of concern given its rapid transmission,” said Mene Pangalos, Executive Vice President, BioPharmaceuticals R&D at AstraZaneca said.
Are there other new findings on Delta?
On June 11, PHE said in a technical briefing that 28-day case fatality rate for Delta remains low (0.1%) “… though mortality is a lagged indicator and the vast majority of cases are still within the 28 days of follow-up required”.
On Tuesday, The Lancet published an analysis of the Delta variant in Scotland, covering the period between April and June 6. The researchers analysed 19,543 confirmed SARS-CoV-2 infections, of whom 377 were admitted to hospital.
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The researchers said that the Delta variant in Scotland was found mainly in younger, more affluent groups. The risk of hospital admission was approximately doubled in those with the Delta variant when compared to the Alpha variant.
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