LONDON (AP) — The U.K. government plans to offer the first dose of COVID-19 vaccine to every adult by September as the nation’s health care system battles the worst crisis in its 72-year-history.

Foreign Secretary Dominic Raab said Sunday that the government will soon begin a trial of round the clock injections at some locations as it continues to add more vaccination sites to increase the pace of delivery. The National Health Service opened a mass vaccination center on Saturday at the historic Salisbury Cathedral, where injections were accompanied by organ music.

“Our target is by September to have offered all the adult population a first dose,’’ he told Sky News. “If we can do it faster than that, great, but that’s the road map.”

Britain has more than 51 million adults in its population of 67.5 million people.

The ambitious vaccination program comes amid crushing pressures on the National Health Service. Already beleaguered hospitals are admitting another COVID-19 patient every 30 seconds, putting the service in its most precarious situation ever, said Simon Stevens, chief executive of NHS England.

“The facts are very clear and I’m not going to sugarcoat them, hospitals are under extreme pressure and staff are under extreme pressure,’’ he told the BBC. “Since Christmas Day we’ve seen another 15,000 increase in the in-patients in hospitals across England. That’s the equivalent of filling 30 hospitals full of coronavirus patients.”

Britain’s health care system is staggering as doctors and nurses battle a more contagious variant of the coronavirus coupled with cold, wet winter weather that drives people inside, where infections spread more easily.

Britain has reported 88,747 coronavirus-related deaths, more than any other country in Europe and the fifth-highest number worldwide.

Prime Minister Boris Johnson on Jan. 2 ordered England into its third national lockdown in an effort to slow the spread of the virus and protect the NHS, which Stevens said now has some 50,000 employees off work due to COVID-19 infections and exposure quarantines.

The government says it won’t review the lockdown measures until mid-February, by which time it plans to offer at least one dose of vaccine to everyone over 70, as well as to frontline health care workers and others who are especially vulnerable to COVID-19.

Once that goal has been reached, the U.K. will offer the vaccine to everyone over 50 before finally moving on to everyone over 18.

Unlike other nations, Britain has chosen to stretch out the time between vaccine doses from 21 days to up to 12 weeks — a decision that means more people will get at least one dose more quickly.

Britain has approved three vaccines — ones by Pfizer-BioNTech, Oxford-AstraZeneca and Moderna. The first two are already being used, while the Moderna doses are not expected until spring.

Meanwhile, vaccination centers are being opened in England at some of the country’s great cathedrals. Salisbury Cathedral, which also houses a copy of the Magna Carta, opened its great nave to the public. Others will follow as the rollout continues.

Organ music played as the jabs were delivered at Salisbury. Requests were taken.

“I doubt that anyone is having a jab in surroundings that are more beautiful than this, so I hope it will ease people as they come into the building,” said the Very Rev. Nicholas Papadopulos, Dean of Salisbury.