Studies have shown that the Pfizer vaccine effectiveness declines at a quicker rate than Astra Zeneca, according to new research.

Two doses of Pfizer initially provide greater protection against new Covid-19 variants, such as the Delta variant, however new research show that its efficacy declines quicker than previously thought, the PA reports.

Scientists from the University of Oxford have reported that after four to five months the level of immunity from both vaccines is the similar, with Astra Zeneca remaining in effectiveness throughout.

They also suggest that those infected with the Delta variant after their second jab had similar peak levels of virus to unvaccinated people. These findings have not yet been peer reviewed.

Scientists reaffirmed that while the vaccine will not prevent you from contracting the virus, it will reduce your chance of serious illness and best protect you from the now dominant Delta variant.

Sarah Walker, professor of medical statistics and epidemiology at the University of Oxford, told the PA: “We don’t yet know how much transmission can happen from people who get Covid-19 after being vaccinated – for example, they may have high levels of virus for shorter periods of time.

“But the fact that they can have high levels of virus suggests that people who aren’t yet vaccinated may not be as protected from the Delta variant as we hoped.

“This means it is essential for as many people as possible to get vaccinated – both in the UK and worldwide.”

York Press: Covid-19 vaccine does in the UK (PA)Covid-19 vaccine does in the UK (PA)

Analysis from more than 700,000 Covid-19 swabs revealed that infections with a high viral load, protection a month after the second Pfizer dose was 90% greater than an unvaccinated individual, reducing to 85% after two months and 78% after three.

For AstraZeneca, the equivalent protection was 67%, 65% and 61%, the researchers said.

Pfizer and AstraZeneca vaccine protection 'still very high'

Dr Koen Pouwels, senior researcher at the University of Oxford’s Nuffield Department of Population Health added: “Even with these slight declines in protection against all infections and infections with high viral burden, it’s important to note that overall effectiveness is still very high because we were starting at such a high level of protection.

“It is also worth highlighting that these data here do not tell us about protection levels against severe disease and hospitalisation, which are two very important factors when looking at how well the vaccines are working.”

When analysing the Moderna vaccine, researchers noted it had ‘similar or greater’ effectiveness against the Delta variant as the other vaccines. However, they do not yet have enough information on the second dose of the Moderna jab.

Dr Alexander Edwards, associate professor in Biomedical Technology at the University of Reading, who was not involved in the study, said: “Overall this study is excellent as it shows that although Delta is better at infecting vaccinated people than previous variants, the vaccines still work remarkably well.

“There are subtle differences – between different vaccine types, and some changes over time – but they all work brilliantly.”