Although one can still catch coronavirus after one jab, one dose of the Pfizer or AstraZeneca vaccine substantially reduces the risk of hospitalisation
One vaccine dose reduces the risk of hospitalisation with coronavirus by three-quarters, a recent Public Health England study found.
The observational study — which looked specifically at vaccines’ effectiveness against the Delta variant, first identified in India — focused on the Pfizer and AstraZeneca vaccines. More data were available as these vaccines have been widely used across the UK since January, compared with the Moderna vaccine which only entered into use on 13 April.
The research compared how effective the vaccines were in preventing people falling ill with symptomatic Covid, and how effective they were at preventing hospitalisations associated with the virus.
Against symptomatic Covid, it found that one dose of vaccine was 49 per cent effective in reducing one’s chance of catching symptomatic covid with the Alpha (Kent) variant, but only 31 per cent effective against the more-infectious Delta variant.
With two doses, the vaccines were more than 80 per cent effective in preventing symptomatic illness with coronavirus, with a slightly higher potency against the Alpha variant (88 per cent compared with 80 per cent).
The study also found that one dose of either vaccine substantially reduced the risk of hospitalisation by at least 75 per cent against either variant.
After two doses, the risk of being hospitalised with coronavirus was reduced by more than 92 per cent the study found.
The study’s authors concluded: “After two doses of either vaccine there were only modest differences in vaccine effectiveness with the B.1.617.2 (Delta) variant. Absolute differences in vaccine effectiveness were more marked with dose one.
“This would support maximising vaccine uptake with two doses among vulnerable groups.”
The research was included in PHE’s technical briefing on 18 June, as the case count of the now-dominant Delta soared to 75,953 cases across the UK, growing by 33,630 or 78 per cent since last week.
As of 14 June, 806 people in England had been admitted to hospital with the variant.
The release of this data also follows the government’s decision to delay the easing of lockdown restrictions by a month, in order to increase vaccinations across the UK, with a particular focus on second doses for older and clinically vulnerable adults.
All adults in England have now been invited to book a coronavirus jab.