How effective are Covid vaccines against the Delta variant?

The Delta variant, also known as B.1.617.2, can spread more easily, according to the health experts.

The strain has mutations on the spike protein that make it easier for it to infect human cells.

That means people may be more contagious if they contract the virus and more easily spread it to others. It is now the dominant strain in the UK.

But how well do current vaccines work?

Analysis by PHE shows that two doses of COVID-19 vaccines are highly effective against hospitalisation from the Delta variant.

A third of the population in England is still susceptible to being infected with the Delta variant of Covid-19, according to a scientific adviser

Scientists are looking at how the Delta variant can cause breakthrough cases, or infections among people who are fully vaccinated. So far, they seem to be rare.

In a preliminary analysis, two doses of the Pfizer or Moderna vaccine appeared to be about 88 per cent effective against disease and 96 per cent effective against hospitalization with the Delta variant, according to Public Health England.

The AstraZeneca vaccine was about 60 per cent effective against disease and 93 per cent effective against hospitalization.

Johnson & Johnson has also reported efficacy from its one-shot vaccine against the Delta variant, which researchers estimate to be similar to the AstraZeneca results.

• SEE ALSO: ​Third of population in England ‘still susceptible to Delta variant’

Now vaccine makers are testing booster shots to find out if they can better protect against the Delta variant and other variants that emerge in coming months.

Professor Matt Keeling, from the University of Warwick and a member of Scientific Pandemic Influenza Group on Modelling (Spi-M), said this week a third of the population in England is still susceptible to being infected with the Delta variant.

His team estimate that, by July 19, there will have been 15.3 million symptomatic and asymptomatic infections in the country.

This means that 27.4 per cent of the English population will have been infected and therefore have natural immunity, leaving the rest either vaccinated or unvaccinated.

(PA Graphics)

When taking account of vaccines, which do not work perfectly, the modellers at Warwick calculated that 33 per cent of the population remains susceptible to the Delta variant, which was first identified in India.

Prof Keeling told a briefing: “There’s still a large number of susceptibles out there and we expect infection, cases and hospital admissions to keep increasing between now and July 19th.”

He said keeping hospital admissions low “and below what we saw in January” really does rely on individual behaviour, as he backed calls for people to take it slowly when restrictions are released.

He said experts do not know about drops in immunity in any great detail and “any waning immunity” could alter the figures, pushing up cases.

He added: “You almost need to think of this like a spring-like system, and, if you suddenly release it, you get a much, much bigger wave than if you gradually let things change.”

What are the symptoms of the Delta variant?

The symptoms are similar to those seen with the original coronavirus strain and other variants, including a persistent cough, headache, fever, and sore throat.

At the same time, COVID-19 patients in the U.K. have reported that some symptoms are slightly different for Delta, according to data from the ZOE COVID Symptom Study. Cough and loss of smell seem to be less common.

Headache, sore throat, runny nose, and fever seem to be more common.