Covid-19: AstraZeneca, Pfizer vaccines found effective against Delta variant, but both doses crucial

A UK based study has found that the Covid vaccines used to inoculate major global population is effective against the Delta variant of the virus, also a major contributor in the surge in cases in India in April and May causing the second wave.

What are the new findings?

Two doses of Covid-19 vaccine was found to be highly effective against the Delta variant, although not preventing the disease altogether but the decreasing need for hospitalisation due to the Delta variant. Moreover, the scientific analysis now in Public Health England journal found no deaths among the vaccinated who were studied.

The effectiveness of two vaccines was studied for the purpose, BioNTech’s ‘ mRNA vaccine, Pfizer and Oxford-Astrazeneca’s vaccine. While the former was found 96 per cent effective against the Delta variants, the later is 92 per cent effective after two doses. Astrazeneca’s Covishield vaccine manufactured by Serum Institute of India has inoculated the majority (88 per cent) of the population in India so far.

How the scientific analysis was conducted

Researchers studied 14, 019 Covid-19 cases of the Delta variants, out of which 166 seeking critical care. All symptomatic Covid-19 cases that occurred between April 12 and June 4 were linked to the Emergency Care Dataset (ECDS) that records all hospital admissions through emergency departments of England.

In its analysis, London School of Hygiene and Tropical Medicine, London and Guys, and St Thomas’s Hospital NHS Trust, London found that the vaccine effectiveness in preventing hospitalisation for cases with Delta variant of SARS-Cov-2 is as significant as Alpha i.e upto 96 per cent after two doses of Pfizer vaccine and up to 92 per cent with Oxford-Astrazeneca vaccine. (71 per cent with one dose)

The paper, that is not yet peer-reviewed concluded that both the vaccines offered a high level of protection against the Delta variant of coronavirus.

Key take-aways

According to Matt Hancock, Health and Social Care Secretary, both the vaccine doses are important as soon as they are available to get maximum protection against all existing variants and the ones that are in the level of mutation.

AstraZeneca further cleared that according to the data from PHE, the vaccine’s effectiveness for milder symptomatic patients was lower 74 per cent for Alpha variant that was found predominantly in the UK and 64 per cent against Delta variant. Higher efficiency against case of hospitalisation with severe symptoms was supported by T-sell response to the vaccine thus providing high and durable protection.

The study findings also reassert that vaccination with Covishield has a significant impact in reducing hospitalisation in the country.

New findings on Delta variant

Public Health England in its briefing said that the 28-day case fatality rate for Delta is 0.1 per cent although there is a vast majority of cases within the 28 days of follow-up required.

Another analysis of Delta variant was done in Scotland and published covered a period between April 6 and June 6. About 19, 500 confirmed Covid-19 cases were analysed out of which 377 sought hospital admission. The findings also concluded that the Delta variant affected the younger more affluent group. The risk of hospitalisation is more or less double than then in Alpha variant, the study further asserted.