© Provided by The iA Government mobile Covid-19 testing unit sets up in Walsall to track down a South African coronavirus variant found in the area in February (Photo: Getty/Christopher Furlong)
Concerns over the South African variant and a deadlier, lesser-known strain first identified in Nigeria are rising among Government scientific advisers after an uptick in cases of both in the UK over the past week, i has learned.
The next stage in the roadmap for relaxing restrictions in England has been given the go-ahead for Monday, after the threat from new variants and three other measures were deemed to be under control.
However, latest figures seen by i show there have now been more than 470 cases of the South African variant, B1351, compared to around 400 a week ago, and 150 at the start of February.
For the Nigerian variant, labelled B1525, there were fewer than 100 cases at the end of February but by the end of March this had risen to around 250 and by this week has climbed above 300.
While the figures are still in the hundreds, and are outweighed by the dominant Kent variant with more than 150,000 cases to date, scientific advisers to the Government are concerned that, as more people are vaccinated, B1351 and B1525 will spread more widely as the virus tries to escape the immunity created by the jabs.
Both strains carry the E484K mutation which can reduce the protection offered by vaccines.
A senior Sage source said: "If it can infect and transmit in vaccinated people, B1351 (SA) will increase in that population. It is slowly going up, but that might be because we are looking for it so hard."
Earlier this week, the Government's chief scientific adviser, Sir Patrick Vallance, said: "What may happen as more people become immune to the virus through vaccination is that the virus will try and get around that to try to escape the vaccine. That's a normal process that viruses do."
B1525 is currently classed as a "variant under investigation" but officials are examining whether to upgrade it to a "variant of concern", alongside the South African and Kent strains, to step up vigilance.
The Nigerian variant has a higher case fatality rate, at 4.3 per cent, than the South African strain at 2.2 per cent and the Kent variant at 2.3 per cent, according to documents seen by i. B1351 has so far accounted for nine UK deaths while 12 people have died with the B1525 variant.
Last weekend ministers announced all UK adults would be eligible for twice weekly asymptomatic testing, and while this was always on the cards, a source said the timing was linked to concerns about new variants.
The Government's scientific advisory committee, Sage, has called for increased testing at UK borders to prevent further cases linked to travel.
In France, between 5 per cent and 10 per cent of new cases are of the South African variant.
Travellers arriving in the UK from France and other countries not on the "red list" have to go into self-quarantine and produce evidence of a negative test.
However, there have been concerns of forged test results as well as travellers not sticking to quarantine rules.
However both B1525 and B1351 are also accounting for transmission in the community as well as foreign travel.
On Monday, Professor Neil Ferguson of Imperial College London, an adviser on the Government's The New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) committee which is monitoring new variants, said testing at borders needed to be stepped up beyond those arriving from red list countries, who have to quarantine in designated hotels.
He said: "I think it would be sensible for at least everyone to be tested when they are coming in."
At the Downing Street press conference earlier this week, the Government's chief scientific adviser Sir Patrick Vallance said: "What may happen as more and more people become immune to the virus through vaccination is that the virus will try and get around that to try to escape the vaccine. That's a normal process that viruses do."
In its latest assessment of the UK epidemic, Sage said: "The widespread transmission of a variant that circumvents vaccine-induced and naturally acquired immunity is a realistic possibility.
"Some parts of continental Europe have relatively high prevalence of B1351, and this variant in particular is of great concern, given the known reduced protection against mild to moderate disease from certain vaccines for this strain . a large proportion of the UK population would be susceptible to B1351, whether they have been vaccinated or not."