New data published by Pfizer suggests getting a third shot of its coronavirus jab can confer greater protection against the Delta variant. The Delta variant entered UK shores ahead of many countries but luckily the vaccine uptake stopped it from driving up hospitalisations, although the lifting of restrictions has raised fears of that prospect. The data released by Pfizer will intensify calls for a booster shot in the Autumn.
The data suggests a third shot builds on the protection offered by the two previous doses.
The data suggest antibody levels against the Delta variant in people ages 18 to 55 who receive a third dose of vaccine were greater than five-fold those stimulated by a second dose.
When administered to an older cohort, the results were even more impressive.
Among people ages 65 to 85, antibody levels against the Delta variant after receiving a third dose of vaccine were greater than 11-fold than following a second dose, the Pfizer data suggests.
There’s “estimated potential for up to 100-fold increase in Delta neutralisation post-dose three compared to pre-dose three”, researchers wrote in the Pfizer data slides.
It is important to note that the data have not yet been peer-reviewed or published.
The data also show that antibody levels are much higher after a third dose than a second dose against the original coronavirus variant and the Beta variant, first identified in South Africa.
It comes after an analysis conducted by Public Health England (PHE) last month found the Pfizer vaccine was 96 percent effective against hospitalisation after two doses.
The same analysis found the AstraZeneca vaccine was 92 percent effective against hospitalisation after two doses.
These are comparable with vaccine effectiveness against hospitalisation from the Alpha variant that ripped through Britain last Autumn.
The analysis included 14,019 cases of the Delta variant – 166 of whom were hospitalised – between 12 April and 4 June, looking at emergency hospital admissions in England.
PHE had previously published analysis showing that one dose is 17 percent less effective at preventing symptomatic illness from the Delta variant, compared to Alpha, but there is only a small difference after two doses.