The Delta variant of coronavirus, first identified in India, doubles the risk of hospitalisation compared with the Alpha variant first found in the UK, but Pfizer and AstraZeneca vaccines provide good protection against the strain, says a study published in The Lancet journal.
Researchers at Public Health Scotland and the University of Edinburgh, UK, found that the Pfizer-BioNTech vaccine offered better protection against the Delta variant compared to the Oxford-AstraZeneca preventive, known as Covishield in India.
The analysis covered the period from April 1 to June 6, 2021, for the demographic distribution of cases.
The team analysed 19,543 confirmed SARS-CoV-2 infections over the period of interest, of whom 377 were admitted to hospital for COVID-19 in Scotland.
Around 7,723 community cases and 134 hospitalisations were found to have the Delta variant of coronavirus.
The study found that the Pfizer vaccine offered 92 per cent protection against the Alpha variant and 79 per cent against the Delta strain two weeks after the second dose.
For AstraZeneca’s vaccine, there was 60 per cent protection against Delta compared with 73 per cent for Alpha variant, the researchers said.
They also found that two doses of vaccine provide much better protection against the Delta variant compared to a single dose.
“Risk of COVID-19 hospital admission was approximately doubled in those with the Delta variant of concern (VOC) when compared to the Alpha VOC, with risk of admission particularly increased in those with five or more relevant comorbidities, the authors of the study noted.
“Both the Oxford AstraZeneca and Pfizer BioNTech COVID-19 vaccines were effective in reducing the risk of SARS-CoV-2 infection and COVID-19 hospitalisation in people with the Delta VOC,” they said.
However, the researchers noted that these effects on infection with Delta variant appeared to be diminished when compared to those with the Alpha VOC.
The authors of the study warned that the vaccine comparison should be interpreted with caution due to differences in the groups which received each type of vaccine, and also in how quickly immunity is developed with each shot.