An NHS chief said the vaccination appeared to have “broken the chain” between catching a coronavirus and a serious illness.
NHS Providers CEO Chris Hopson said the number of hospitalizations with the Covid-19 variant, first discovered in India – known as the Delta variant – was not increasing “very significantly”.
Many of Bolton’s patients – with the largest number of cases of the Indian variant in England – were younger than in the previous waves of the pandemic, he told BBC Breakfast.
“The people who came into this circle were actually much younger and were much less at risk of very serious complications, less at risk of death, and that meant they were less in demand from critical care.” , he said.
“What we think we can start saying now, based on this experience, is that vaccines seem to have broken the chain between catching Covid-19 and potentially very, very seriously ill and potentially dying.
“There were very, very few people who had these double stings and were able to get that accumulation of protection after those stings.”
In the final phase of the pandemic, the number of people in hospital in Bolton with Covid-19 reached 50, compared with 170 in November and 150 in January and February, Hopson said.
“The rate of infection is increasing in a number of different places,” he said.
“We know that hospitalizations are increasing, the percentage of people admitted to hospitals in these areas is increasing. But they do not rise very significantly.
Of the 12,431 cases of the Indian variant confirmed so far in the United Kingdom, 10,797 are in England, 1,511 in Scotland, 97 in Wales and 26 in Northern Ireland.
In England, cases are widespread across the country, and the most affected areas include Bolton in Greater Manchester (2149 cases), Blackburn with Darwen in Lancashire (724), Bedford (608), Leicester (349), Manchester (278) and Birmingham ( 223).
Dr Adam Kucharski, an epidemiologist at the London School of Hygiene and Tropical Medicine, said the transmission of the Indian version could see a “large number” of people admitted to hospital with coronavirus.
A member of the government’s scientific advisory committee on scientific pandemic influenza modeling (Spi-M), Dr Adam told Today Radio BBC Radio 4 that after early evidence that first-dose vaccines were less effective against the Delta variant.
He added: “I think it is this increase in transmission that will potentially create significant problems for us.”
Dr Kurcarski said the current picture meant that it was “difficult to be sure” that a “large number” of people would not be hospitalized due to the spread of the Indian variant and the number of adults still unvaccinated in the UK.