Delta variant 60% more transmissible, reduces vaccine effect

London, Jun 11 (PTI):
The Delta variant of COVID-19, or the B1.617.2 variant of concern (VOC) first identified in India, is about 60 per cent more transmissible than the Alpha strain identified in the UK and also reduces the effectiveness of vaccines to some extent, UK health experts report on Friday.
Public Health England (PHE), which has been tracking VOCs on a weekly basis, said that the cases of the Delta VOC have risen by 29,892 to hit 42,323 in the country an increase of around 70 per cent.
The latest data also indicates that over 90 per cent of new COVID-19 cases in the UK are now the Delta variant, which continues to show a significantly higher rate of growth compared to the Alpha VOC which was first identified in the region of Kent in England and was the dominant variant in the country so far. New research from PHE suggests that the Delta variant is associated with an approximately 60 per cent increased risk of household transmission compared to the Alpha variant. Growth rates for Delta cases are high across the regions, with regional estimates for doubling time ranging from 4.5 days to 11.5 days, PHE said in its latest analysis.
There are now analyses from England and Scotland supporting a reduction in vaccine effectiveness for Delta compared to Alpha. This is more pronounced after one dose (absolute reduction in vaccine effectiveness against symptomatic infection of approximately 15 per cent to 20 per cent after one dose), its risk assessment analysis reads.
Iterated analysis continues to show vaccine effectiveness against Delta is higher after two doses but that there is a reduction for Delta compared to Alpha. There is uncertainty around the magnitude of the change in vaccine effectiveness after two doses of Oxford-AstraZeneca vaccine, it adds. PHE said that with the Delta variant now accounting for the overwhelming majority of new cases in the UK, it is encouraging to see that the increase in cases is not yet accompanied by a similarly large increase in hospitalisations. PHE will continue to monitor closely over the next few weeks, but the data currently suggest that the vaccination programme continues to mitigate the impact of this variant.