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Second shots of coronavirus vaccine could be delayed even further amid growing evidence that spacing out the doses improves their effectiveness.
The NHS vaccination programme aims to immunise about 14 million people at greatest risk of Covid by mid-February, with second doses due to be given up to 12 weeks later.
But Public Health England’s head of immunisation, Mary Ramsay, told MPs on Wednesday that if infection data showed vulnerable groups, such as the over-80s, were well protected by their first shot, then second doses could be delayed to get a first jab to younger people as well.
The NHS originally planned to offer second shots of the Pfizer vaccine three weeks after the first in line with the procedure in the trials, but the soaring infection rate forced a rethink in late December with the Joint Committee on Vaccination and Immunisation (JCVI) recommending first shots for as many people as possible in the highest-risk groups.
“Like we changed the schedule very quickly before Christmas, this is a very fast-moving field, and if more data emerges it may well be that the balance of those first doses, getting more first doses to people is a priority,” Ramsay told the Commons science committee. “If we’re seeing very high levels of protection, for example in the vulnerable groups, it may be more important to get more younger people vaccinated.”
Ramsay said Public Health England would review infection data weekly and that it may be possible to be “a little bit more relaxed” about the timing of second doses, depending on vaccine supply and the scientific evidence. Asked if second shots might be given beyond the current 12-week limit, she said: “That’s unlikely, but it’s always possible.”
Evidence now suggests that spacing out doses of the AstraZeneca/Oxford vaccine may be more effective at protecting people. Clinical trials revealed the efficacy of the vaccine was substantially higher, at 90%, in a subgroup of people who received half a dose followed by a full dose, rather than two full doses, which had an efficacy of 62%.
But Prof Wei Shen Lim, the chair of the Covid-19 immunisation group of the JCVI, told MPs that further analysis by AstraZeneca showed the improved protection came from spacing out the doses.
“People who had the half dose then full dose were those who were vaccinated at a longer time interval, roughly six to 12 weeks, and what they’ve seen in their data is that people who have the second dose later probably have a three times higher antibody level than those who were vaccinated earlier. So if anything, it suggests that increasing the dose interval is beneficial,” he said.
Sir Mene Pangalos, the executive vice-president of biopharmaceuticals research and development at AstraZeneca, told the committee the first vaccine shot was more protective over time.
”What we’re seeing with our data so far is that as you go to the eight- to 12-week interval, you actually increase vaccine efficacy. People are protected enough with the first dose, to around 70%, but we see that within that eight- to 12-week interval is actually the sweet spot,” he said.
Lim said the JCVI had yet to decide how vaccine shots might be prioritised during the second phase of the rollout, once healthcare workers, those with underlying conditions, and the over-50s had received their shots.
He said essential workers may be prioritised. Modelling suggests one life is saved for every 25 to 40 people vaccinated in care homes, and for every 250 people vaccinated over the age of 80, he added, while “thousands” of train operators would need to be immunised to save one life, he said.
AstraZeneca is “imminently” scaling up to release 2m doses of its vaccine a week in the UK, and may be able to go above that from April, the firm’s chief executive said. Tom Keith-Roach, the president of AstraZeneca UK, said 1.1m doses of the company’s Covid-19 jab developed with Oxford University had been released to the UK to date, but the aim was to reach 2m doses per week on or before the middle of February.
Nadhim Zahawi, the minister in charge of the vaccine rollout, said the immunisation programme would be slower than some countries because we have chosen to vaccinate all those at highest risk of dying, such as people in care homes who are harder to reach. “Some of the countries have chosen to say, you know what, we will vaccinate anyone over the age of 60, as Israel’s done. That’s much easier to do.”
He said there were “absolutely no plans” to issue vaccine passports that could allow people who had been immunised to travel or enjoy more freedom from the restrictions.
Firstly, he said, the vaccines protect against people getting ill but nobody knows whether they prevent transmission. “Secondly, it will be discriminatory because they’ll be those who, for a number of reasons may not be able to be vaccinated or choose not to,” he told the committee.
He agreed with Pangalos, who asked for vaccine production workers to be given priority immunisation because of the urgency of their work.
Source: The Guardian
Keyword: Second shots of Covid vaccine could be delayed further in England | World news