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AstraZeneca Covid vaccine ‘as effective’ as Pfizer after 4-5 months

Covid vaccines


The AstraZeneca Covid vaccine is ‘as effective’ as the Pfizer jab after 4-5 months, a UK study has found.

Researchers said being fully vaccinated is still the most effective protection against the Covid-19 Delta variant, which is currently dominant in the UK.

Both doses of the Pfizer vaccine are initially more effective but efficacy decreases quicker than a double dose of AstraZeneca. Long-term outcomes need to be looked at, said the study.

Two weeks after the second dose, Pfizer was 93% effective against symptomatic infection, whereas AstraZeneca was 71%.

AstraZeneca and Pfizer vaccinations offer ‘good protection’ against new infections of the Delta variant but this is still less effective compared with the Alpha variant.

The study examined 2.5m test results from 743,526 participants in the UK’s Covid-19 household-infection survey, run by the University of Oxford and the Office for National Statistics.   

Professor Sarah Walker, professor of medical statistics and chief investigator for the survey, said ‘both of these vaccines are still doing very well against Delta… when you start very very high, you’ve got a long way to go’.

Other findings included that the time between jabs has no bearing on the effectiveness of preventing new infections, but younger people will have greater protection from vaccination than older people.

And, people who have had Covid receive even more antibodies once double-vaccinated.

There was insufficient data for Moderna, but the study said a single Moderna dose has ‘similar or greater effectiveness against the Delta variant as single doses of the other vaccines’.

Trial results from earlier this month showed Moderna’s Covid-19 vaccine is still 93% effective six months after the second dose is given.

The study comes as Germany announced this month that it would give a booster mRNA (Pfizer or Moderna) vaccine to anyone who was double-vaccinated with the a vector vaccine (AstraZeneca or Johnson & Johnson).

A version of this story originally appeared on Nursing in Practice’s sister title Pulse.

To complete relevant vaccination and infections CPD modules on Nursing in Practice Learning, click here.