The Delta variant, which is now responsible for most coronavirus infections in England, is not driving a surge in the rate of hospitalizations there, according to data released by Public Health England on Thursday.
Although the number of coronavirus infections has risen sharply in recent weeks, hospitalization rates remain low. Between June 21 and June 27, the weekly hospitalization rate was 1.9 per 100,000 people, the same as it was the previous week.
The hospitalization rate has increased slightly over the past month, rising from 1.1 admissions per 100,000 people in early June, according to the agency’s data. But it remains considerably lower than during England’s surge last winter, when the hospitalization rate peaked at more than 35 admissions per 100,000 people.
The data suggest that countries with high vaccination rates are unlikely to see major surges in hospitalization rates from Delta. Nearly 75 percent of adults in England — including 95 percent of those who are 80 or older — have had at least one shot, according to the agency’s numbers.
Earlier this month, England had delayed its plans to reopen after Delta caused a spike in new cases.
Case rates are highest among young adults, who are the least likely to be vaccinated, Public Health England reported. (Among those under 40, just 34 percent have been at least partially vaccinated.) Young people are less likely to develop severe Covid-19, which could explain why the spread of Delta has not resulted in a wave of hospitalizations.
Breakthrough infections, or those that occur in people who are fully vaccinated, tend to cause mild or no symptoms.
At a separate news conference on Thursday, the European Medicines Agency noted that vaccination should provide good protection against Delta.
“We are aware of the concerns that are caused by the rapid spread of the Delta variant and all the variants,” Marco Cavaleri, the head of biological health threats and vaccine strategy at the agency, said at the briefing. Given the research that has been done so far, the four vaccines that are approved in the European Union — Pfizer-BioNTech, Moderna, AstraZeneca and Johnson & Jonson — all seem to protect against the Delta variant, he said.
In one recent study, for instance, researchers found that the Pfizer vaccine was 88 percent effective at protecting against symptomatic disease caused by Delta, a performance that nearly matches its 95 percent effectiveness against the original version of the virus. A single dose of the vaccine, however, is much less effective.
“Expediting vaccination and maintaining public health measures remain very important tools to fight the pandemic,” Dr. Cavaleri said. “In particular, making sure that vulnerable and elderly people complete their vaccination course as soon as possible is paramount.”