The Delta strain (B.1.617.2) was formerly referred to as the Indian variant.
Public Health England (PHE), in a pre-print, said that the Pfizer/BioNTech COVID-19 vaccine was 96% effective against hospitalization from the Delta variant after two doses, while Oxford/AstraZeneca’s offered 92% protection against hospitalization by that variant.
The UK agency said vaccine effectiveness against hospitalization with Delta was similar to that seen with Alpha, previously known as the Kent variant.
The PHE said the analysis included 14,019 cases of the Delta variant – 166 of whom were hospitalized – between April 12 and June 4, looking at emergency hospital admissions in England.
While the data provides additional evidence that two doses of those COVID-19 vaccines still protect against severe disease, it suggested that vaccine effectiveness against milder symptomatic disease, although significant, was lower.
Further work remains underway to establish the level of protection against mortality from the Delta variant, said PHE. “However, as with other variants, this is expected to be high.”
PHE has previously published analysis showing that one dose is 17% less effective at preventing symptomatic illness from the Delta variant, compared to Alpha, but there is only a small difference after two doses.
'Hugely important findings'
Dr Mary Ramsay, head of immunization at PHE, said: “These hugely important findings confirm that the vaccines offer significant protection against hospitalization from the Delta variant.”
She said it was vital individuals get both doses to gain maximum protection against all existing and emerging variants.
UK vaccines minister, Nadhim Zahawi, said the data showed vaccines are continuing to help break the link between hospitalization and the Delta variant after one dose, and demonstrated the high effectiveness of two doses.
Mene Pangalos, executive vice president, BioPharmaceuticals R&D, AstraZeneca, said: “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. The data show that the vaccine will continue to have a significant impact around the world given that it continues to account for the overwhelming majority of supplies to India and the COVAX facility.”
Last week, PHE said that more than 90% of new COVID-19 cases in the UK involve the Delta variant, while the strain is a key contributor to the current wave of infection in the Indian subcontinent and beyond.