COVID-19: Delta variant increases hospitalisation risk but vaccine protection remains high, study suggests

The risk of being hospitalised with the Delta (Indian) variant of coronavirus is around double that of the Alpha (Kent) strain, but two vaccine doses still provide strong protection against it, new data suggests.

However, the level of protection against the Indian variant of COVID-19 may be lower than with the Kent variant, early research published in The Lancet suggests.

Data analysed from 5.4 million people in Scotland shows that the Delta variant is now the dominant form of the virus in the country.

There were 19,543 community cases of COVID during the period studied – 1 April to 6 June – with 377 hospital admissions where a specific variant was confirmed.

A total of 7,723 cases and 134 hospital admissions were found to have the Delta variant, which is thought to be about 60% more transmissible than the Alpha variant.

Researchers said that those with underlying conditions were more at risk of being admitted to hospital, as has been the case with previous variants.

They found that while vaccines reduced the risk of being admitted to hospital, strong effects against the Delta variant were not seen until 28 days after the first jab.

The Pfizer-BioNTech jab was found to provide 79% protection against infection from the Delta variant, compared with 92% against the Alpha strain.

The Oxford-AstraZeneca jab offered 60% protection against infection with the Delta variant – compared with 73% for the Alpha variant.

According to experts, the lower vaccine effect may reflect the fact that it takes longer to develop immunity after having the Oxford vaccine.

The study was funded by the Medical Research Council, UK Research and the Innovation Industrial Strategy Challenge Fund and Health Data Research UK (HDR UK) – and was supported by the Scottish government.