Vaccines provide strong protection against being hospitilised with the Indian or delta Covid variant, a major study has shown, raising hope that Britain will soon be able to release restrictions.
New data from a nationwide study in Scotland reveals that although the risk of being admitted to hospital is doubled for people catching the Indian mutation, the vaccines are still very effective.
The variant is now the dominant strain of Covid in the country and is thought to be between 41 and 60 per cent more transmissible.
The Government is expected to announce on Monday that it will extend the June 21 unlocking date for a further four weeks to make sure that the link between infections, admissions and deaths has been broken.
But data released on Monday from the University of Edinburgh and Public Health Scotland (PHS) show the risk from the Indian variant is cut by 70 per cent for people who have been fully vaccinated.
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Although the team found a slight dip in vaccine effectiveness between the Kent or alpha variant and the Indian strain, they also found there are "very few" over-65s testing positive for Covid, suggesting the jabs are protecting the most vulnerable.
The Scottish team calculated that for people who had two doses or who had their first dose at least four weeks ago, the risk of being hospitalised with the Kent variant was reduced by 72 per cent and the Indian variant by 62 per cent.
In community cases at least two weeks after the second dose, the Pfizer/BioNTech jab was found to provide 79 per cent protection against infection from the Indian variant, compared with 92 per cent against the Kent strain.
The Oxford/AstraZeneca vaccine offered 60 per cent protection against infection with the Indian variant compared with 73 per cent for the Kent variant.
Officials at Public Health Scotland said they were optimistic that the vaccine programme could keep infections down.
Dr Jim McMenamin, the national Covid-19 incident director at PHS, said: "We do appear to show that delta variant does increase the risk of hospitalisation. However, what we are able to see is that our vaccines are still highly effective.
"These results provide early encouragement that two doses of either Pfizer/BioNTech or Oxford/AstraZeneca vaccines significantly reduce the risk of infection against both the alpha or new delta variants.
"I am still optimistic about the benefits – it’s just that we need to encourage everyone to come forward and take up the offer of vaccination."
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The team said a delay to the June 21 reopening would mean more people could get their second jab and gain further protection.
Prof Aziz Sheikh, director of the Usher Institute and professor of primary care research and development at the University of Edinburgh, said: "The key message is that we are seeing strong vaccine protective effects after the second dose, so this is a different picture. Getting people second doses and giving people reasonable amounts of time is key here really.
"If there is a delay, that will give us the opportunity to widen coverage, and for those who have only got one dose what we want is a period of time where people can maximise their immune response. So any increase in the window of opportunity before lockdown measures are brought to an end will be helpful, because that will help us to control community transmission."
The findings are published as a research letter in The Lancet.