Fourth Covid vaccines are not currently needed, British government scientific advisers have said, amid increasing evidence the Omicron strain is much milder than previous variants. 

On Friday night, the Joint Committee on Vaccination and Immunisation (JCVI) announced that booster jabs continue to provide high levels of protection against severe disease from Omicron in older adults, including the most vulnerable. 

The committee's analysis found that, three months after receiving a third jab, protection against hospitalisation among those aged 65 and over remains about 90 per cent. 

Ministers have been exploring the possibility of a fourth jab for several weeks after Israel, considered a global pioneer in Covid vaccination, launched such a programme last month. 

But Prof Wei Shen Lim, the JCVI's chairman of Covid immunisation, said: "The current data show the booster dose is continuing to provide high levels of protection against severe disease, even for the most vulnerable older age groups. 

"For this reason, the committee has concluded there is no immediate need to introduce a second booster dose, though this will continue to be reviewed." 

It comes as Covid numbers in Britain fell for a third day in a row and evidence emerged that hospitalisations arising from virus cases were 12 times lower than during last year's winter peak. 

There were 178,250 cases reported in the UK on Friday, down from 179,756 the previous day and a daily fall of more than 11,000 from the previous week. 

New figures from Scotland show just 1 per cent of people who test positive for Covid are ending up in hospital – down from 12 per cent last January. 

Data from England shows the number of patients in mechanical ventilation beds has fallen to 728 – a decline of 63 in a week and the lowest it has been since October. 

Speaking during a visit to King's College Hospital in south London, Sajid Javid, the Health Secretary, said: "When we look at Omicron versus the previous variants, of course there are some encouraging signs. We know now that Omicron is less severe." 

However, Javid emphasised the need for people to come forward for their booster jabs amid "challenging times" for the NHS. 

On the same visit, Amanda Pritchard, the head of the NHS, said a fortnight of further hospital admissions for Covid was "already baked in" as some NHS staff faced "the steepest climb of the pandemic yet". 

Staff absences because of Covid isolation are continuing to put severe pressures on services, amid warnings the situation could continue for some weeks. 

The JCVI said rolling out a fourth jabs programme "would add to the significant existing operational pressures", noting that "the current Omicron wave is progressing very swiftly, offering limited time for additional vaccine programme measures to have a substantial impact within this wave". 

Britain's Health Secretary Sajid Javid, left, meets staff in a Covid-19 Intensive Care Unit during a visit to Kings College Hospital in London. Photo / AP 

The committee said that, even among the most vulnerable, a fourth jab would provide "limited additional benefit against severe disease at this present time" and that the main aim of the vaccination programme remained prevention of severe disease, not protection against mild or asymptomatic infection. 

Protecting against all infection would require regular jabs – as often as every three months – which "is not considered a sustainable long-term strategy", they said. 

The committee added that alternative vaccines including variant-specific jabs, which could become available later this year, may prove better suited to providing long-term protection against novel variants. 

The comments echo remarks made earlier this week by Sir Andrew Pollard, the chairman of the JCVI, who told The Telegraph that "more strong evidence is needed" before the rollout of a fourth vaccine. 

He said: "We can't vaccinate the planet every four to six months. It's not sustainable or affordable. In the future, we need to target the vulnerable." 

There is increasing evidence that Omicron is milder than previous variants. The latest figures show an increase in hospitalisations, with 2434 admissions on Friday – up from 2080. But NHS data shows that, in some areas, as many as 45 per cent of patients in hospital with Covid were admitted for other reasons. 

Figures calculated from the change in number of Covid patients in hospital for the week ending December 28. Photo / NHS 

There were 13,045 people included in the official Covid hospital figures by January 4, but 4825 had been admitted for other reasons. Across the country, 37 per cent of Covid hospital patients were admitted for other reasons, compared with a figure of 24 per cent earlier this month. 

The figures show that, in the week ending January 4, cases of "incidental" Covid rose by 135 per cent, from 2,065 to 4,845. Those classed as primarily Covid saw lower growth, of 83 per cent, from 4,479 to 8,200. 

The Midlands had the highest proportion of "incidental" cases, at 45 per cent. In London, the percentage of non-Covid cases included in the figures hit a high of 44.7 per cent on January 2 but has since fallen to 38.2 per cent. 

The latest statistics show deaths from Covid in care homes are up to 10 times lower than this time last year, even though there has been a greater number of outbreaks. 

Data from Public Health Scotland shows only one in 100 people who recently tested positive for Covid required hospital care, compared to one in eight at the end of last January. 

Calculations by The Telegraph also suggest in England just 2 per cent of cases compared to 12 per cent last winter are currently ending up in hospital.