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Pfizer trial finds vaccine ‘100% effective’ against South African variant

2 April 2021

12:50 AM

2 April 2021

12:50 AM

Pfizer and BioNTech have released some extraordinary findings from a Phase 3 trial involving 46,307 participants, between seven days and six months after a second dose was administered. The vaccine was found to have a 91.3 per cent efficacy rate. These findings line up with the real world data coming out of Israel, which has used the Pfizer vaccine to inoculate its population, and reported several weeks ago that it proved 94 per cent effective in preventing symptomatic illness.

But on top of the overall efficacy rate came even better news: Pfizer is reporting that the ‘vaccine was 100 per cent effective in preventing severe disease’ as defined by the US Centers for Disease Control. The 32 cases of severe disease were all found in the placebo group, while zero were found in the vaccinated group. What’s more, the vaccine was found to be ‘100 per cent effective in preventing Covid-19 cases in South Africa’, where the new strain is overwhelmingly prevalent: of the 800 participants enrolled in South Africa, ‘nine cases of Covid-19 were observed, all in the placebo group, indicating vaccine efficacy of 100 per cent’. Six of them were the new B.1.351 strain. While many will look forward to seeing bigger studies, early indication suggests the vaccine, in its current form, is robust against the variant.


Today’s findings have big implications for those who have received the Pfizer vaccine, as well as public policy being crafted around protecting the vaccine rollout. Both trial and real world evidence continues to show the Pfizer-BioNTech vaccine is one of the most effective on offer; and its effectiveness against different strains suggests that the need for boosters for those who’ve had the Pfizer jab will be dependent on how long the antibodies it induces last, rather than a need to inoculate against existing variants.

The government’s reasoning for escalating Covid-19 restrictions, especially around travel (including the new requirement to secure permission under a specific list of criteria to leave the country), is based on the notion of a hypothetical variant that can dodge vaccines. While the virus is estimated to have mutated thousands of times since it first started to spread, no known variant currently exists. Still, the fear that one might appear drives its decision-making, with the South African variant frequently cited in recent months as a threat to the UK’s ability to keep the virus under control. Today’s findings suggest that, so far, Pfizer is holding up against new strains: findings which bode well for future ability to ditch Covid-19 rules and return to normal life.

As questions have been raised about the efficacy of the Oxford-AstraZeneca vaccine against news strains – with the crucial caveat that even the study suggesting ten per cent efficacy still found it protected people on the most important measures, including preventing against severe illness and death – evidence is building that in the Pfizer vaccine we have a jab that comes close to full protection. This is particularly good news here in the UK, where the elderly and vulnerable first in line for the jab last December received the Pfizer vaccine, as it was the first one to be approved and made available in Britain. As of 14 March, the most recent data set available, 10.9 million doses of Pfizer were administered, along with 13.7 million doses of Oxford-Astrazeneca. Of the 1.3 million second doses carried out, most have been Pfizer.

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