The Covid-19 variants that have been worrying scientists do not appear to be rising in popular European destinations, UK advisers have said.

While Covid infection rates are still high in countries such as Spain and France, levels of, for example, the South African variant, are staying pretty constant and are not going up, according to scientists advising the Government.

The Kent variant is now so prevalent in many European countries that there is currently no advantage for other variants, and so they are not particularly rising.

Although there are pockets where variant cases appear to be high, they are still only accounting for around 5% of cases or fewer.

As a result, experts believe variants may not become such a problem, depending on what measures countries such as Spain and France take to lock down now.

The advisers believe that in Europe, as has been the case in the UK, there is now a race between increased viral spread and vaccination.

It is still unclear whether vaccines protect against variants, although research published last week suggested the Pfizer jab could offer good protection against the Brazilian and South African variants.

AstraZeneca has also said it hopes its vaccine will protect against severe disease from any variant.

The Government scientific advisers believe that when international holidays resume, PCR tests are needed because they are more sensitive than the cheaper lateral flow tests.

They also argue that PCR tests are the only type that can pick up the presence of variants and will therefore be needed for international travel.

When it comes to herd immunity at home, the scientific advisers believe that is still a way off, with more than 80% of people needing a vaccine to have a hope of reaching herd immunity.

However, they said the vaccine rollout has already put big brakes on transmission and that will increase as more younger people are jabbed.

The comments come as new data from the Office for National Statistics (ONS) shows that about one in 340 people in private households in England had Covid-19 in the week to April 3 – broadly unchanged on the previous week

It is the lowest figure since the week to September 24, when the estimate stood at one in 470.

In Wales, about one in 800 people were estimated to have had Covid-19 in the week to April 3 – down from one in 570 for the week to March 27.

The estimate for Scotland is one in 410, down from one in 320, and for Northern Ireland it is one in 300, down from one in 220.

The R is between 0.8 and 1 across England. Government scientists said the situation is too variable to produce a UK-wide R rate, but R is believed to be above 1 in some parts of the UK.

Scientific advisers said the levels of infection have flattened off, with possible increases in some towns and cities.

Elsewhere, the safety committee of the European Medicines Agency (EMA) has said it is continuing to look at reports of rare blood clots related to the vaccine from Janssen, whose parent company is Johnson & Johnson.

Four serious cases of unusual blood clots with low blood platelets have been reported – one in a clinical trial and three during the vaccine’s rollout in the US. One person has died.

It comes after the EMA said earlier this week that brain blood clots with low platelet count should be regarded as a rare side-effect of the Oxford/AstraZeneca vaccine.

The EMA is also looking at five reports of rare capillary leak syndrome in people who were vaccinated with AstraZeneca.

This syndrome causes leakage of fluid from blood vessels, causing tissue swelling and a drop in blood pressure.

Meanwhile, papers released by the Scientific Advisory Group for Emergencies (Sage) suggest that five days of sequential lateral flow testing may match the effectiveness of a 10-day quarantine period, in terms of adherence to the regime.