Covid cases “rising exponentially” but double doses work, study shows

Coronavirus cases in England are “rising exponentially” among unvaccinated younger people and those yet to have their second jab, according to scientists.

The analysis, from the React-1 study, found that infections increased by 50 per cent between 3 May and 7 June, coinciding with the rise of the Delta variant that is now dominant in the UK.

Data from nearly 110,000 swab tests carried out across England between 20 May and 7 June suggests Covid cases are doubling every 11 days, with the highest prevalence in the North West and on average one in 670 people infected.

The study estimates that the reproduction number (R) is currently 1.44, meaning ten infected people would pass the virus on to 14 others on average.

Experts from Imperial College London said their findings show a “rapid switch” between the Alpha (Kent) variant, which first appeared in the UK in September 2020, and the Delta (India) variant in the last few weeks – with the latter accounting for up to 90 per cent of all coronavirus cases.

The research shows the bulk of infections is being driven by children aged between five and 12, as well as younger adults aged between 18 and 24. Infections in these age groups are around five times higher when compared to those over 65, according to the study.

Steven Riley, professor of infectious disease dynamics at Imperial, said: “Prevalence is increasing exponentially, and it’s being driven by younger ages. Clearly that is bad news, but the key thing to point out here is that we’re now in a very different part of the epidemic – we know there is a lot of immunity in the population.”

“The portion of population that is driving the growth is all the proportion that’s not vaccinated. Rapid rollout and mass vaccination of the younger ages, which is where we see the bulk of the infections, should effectively slow that growth.”

The results also showed that the percentage of people testing positive was highly dependent on being vaccinated. Just 0.6 per cent of fully vaccinated over-65s were found to have an infection, compared to 0.23 per cent of the unvaccinated under-65s.

Prof Paul Elliott, chair in epidemiology and public health medicine at Imperial, said: “I think we take quite a lot of comfort when we look at the details. It does appear there is very good protection where everyone is double vaccinated. 

“There is a delay between vaccines going into the arm and protection, but the sooner we get vaccines in the arms the sooner we’ll get protection.”

He said the government’s plan to vaccinate all adults in the period between now and 19 July will “make a very big difference and increase the total amount of population immunity”.