Wednesday 6 July 2022 12:06 PM Timelapse maps show how 'most contagious Covid yet' has become dominant in ... trends now

Covid's most contagious variant yet is now dominant in England, sequencing data shows as experts warn it could cause send infections to pandemic highs.

Data from the Sanger Institute, one of the UK's largest Covid surveillance centres, shows six in 10 positive swabs it examined in the week to June 25 were the BA.5 version of Omicron.

It has now officially taken over from BA.2, which caused infections to soar past 4million in April and prompted NHS bosses to call for the return of masks just days after No10 abandoned all restrictions to usher in the post-pandemic era.

BA.5 — which is also gathering steam in the US and across Europe — is thought to be a third more transmissible than its ancestor, dubbed just as infectious as measles. However, Government advisers believe it is just as mild.

Experts told MailOnline that the strain could push daily infections to a 'higher point than previously seen'. 

Covid cases have more than doubled over the last month and NHS hospitals have seen admissions among infected patients increase by a third week-on-week.

In light of the current resurgence, officials are said to be considering expanding the autumn booster vaccine campaign to cover all over-50s.

Hours before resigning over a lack of confidence in Boris Johnson, ex-Health Secretary Sajid Javid said he had told the NHS to gear up for a wider programme than anticipated. Provisional guidance recommended restricting jabs to care home residents, over-65s, frontline health and social workers and vulnerable young people.

Since BA.5 was first detected in South Africa in February, experts have been concerned over the speed of its growth. 

Data from the Sanger Institute shows it was behind 58.6 per cent of all infections in the week to June 25 — up by a fifth from one week earlier.

Until now, its prevalence had nearly doubled every week. It caused just 5.8 per cent of infections in mid-May.

Meanwhile, the separate but closely-related Omicron sub-strain BA.4, which was labelled as a variant of concern alongside BA.5, seems to have slowed. 

It was behind just 25.8 per cent of cases in the most recent week, compared to 25.1 per cent one week earlier.

While this data provides the most up to date picture, the researchers noted the positive tests it sequences are not a representative sample of the population. 

And ever since the Government's £2billion-a-month free testing scheme was axed, it has examined fewer swabs — which could raise discrepancies in its data.

However, figures from the UK Health Security Agency (UKHSA) paint a similar picture.

In a report last week, it noted that BA.5 would 'most likely' become dominant in the UK, estimating that 39.5 per cent of all cases in England were caused by the strain by June 15. Its data shows BA.5 was most prevalent in the South East. 

The UKHSA said BA.5's growth advantage over BA.2 would 'plausibly lead to increased community transmission'. 

The formerly dominant strain caused Covid infections to soar to record highs in April. Virus-tracking data from the Office for National Statistics, now considered the best barometer for monitoring the outbreak, showed 4.1million people in England were infected during the last peak. 

Its most recent update — based on tens of thousands of random swabs — show that roughly 1.8million were infected towards the end of June, up by a third on the previous week. 

As well as the new variants, celebrations for the Queen's Platinum Jubilee, half-term holidays and warm weather are also thought to be fuelling the latest surge. Some have also pointed to Britons mistaking Covid symptoms for hay fever. 

Professor Paul Hunter, an infectious disease expert at the University of East Anglia, told MailOnline: 'At present it does look like BA.4/BA.5 together will push total new infections per day to a higher point than previously seen.'

But he added that that BA.5 may cause 'less severe disease on average per infection' compared to earlier strains, although it is too early to know for certain.

'But of course the total amount of severe disease depends on both the number of infections and the risk of severe disease per infection, so [it is] not yet [possible] to say have much severe disease/how many deaths will occur in total,' he added. 

Dr Stephen Griffin, a virologist at the University of Leeds, told MailOnline: 'We have known for some time now that another – the third – significant wave was due to hit the UK and we are now very much within it.'

He said it

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