Vaccine effectiveness and longevity in UK

Impact of Delta on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK

N = 384,543

Households, 221,909

Obtaining two vaccine doses remains the most effective way to ensure protection against Delta

With Delta, Pfizer-BioNTech and Oxford-AstraZeneca vaccines still offer good protection against new infections

but effectiveness is reduced compared with Alpha

However, Delta infections after two vaccine doses had similar peak levels of virus to those in unvaccinated people

(with the Alpha variant, peak virus levels in those infected post-vaccination were much lower)

Two doses of either vaccine still provided at least the same level of protection as having had COVID-19 through natural infection

People who had been vaccinated after already being infected with COVID-19 had even more protection than vaccinated individuals who had not had COVID-19 before

Two doses of Pfizer-BioNTech have greater initial effectiveness against new COVID-19 infections

but this declines faster compared with two doses of Oxford-AstraZeneca

After four to five months, effectiveness of these two vaccines similar

however, long-term effects need to be studied

The time between doses does not affect effectiveness in preventing new infections

Younger people have even more protection from vaccination than older people

UK, third shots

Prof Peter Openshaw

New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG

We can't just look at the antibody levels and think that that equates to levels of protection

It still seems that you get a lot of protection from these vaccines, even if the antibody levels have drifted down to some sort of stable level