Germany’s vaccine regulator said on Tuesday it has recorded 31 cases of a rare blood clot in the brain, nine of which resulted in deaths, after people received a COVID-19 vaccine from AstraZeneca.

The Paul Ehrlich Institute (PEI) said it has now registered 31 cases of clots in the cerebral veins – known as sinus vein thrombosis, or CSVT – and that in 19 of these there was a deficiency of blood platelets or thrombocytepenia.

In nine cases, the affected people died. With the exception of two cases, all reports concerned women between the ages of 20 and 63. The two men were 36 and 57 years old.

It comes as Berlin’s state hospital groups Charite and Vivantes stopped giving women under the age of 55 the AstraZeneca vaccine.

A spokesperson for the hospitals said on Tuesday: “From the Charite’s point of view, this step is necessary because in the meantime further cerebral venous thromboses have become known in women in Germany.”

With more than half of of people in England now thought to have antibodies against coronavirus, how close is the UK to achieving “herd immunity”?

Herd immunity refers to immunity that is built up when a large part of a population of an area is immune to a specific disease. While not every single individual may be immune, the group as a whole is protected due to a reduction in the number of high-risk people overall.

This infographic created by Martin Armstrong and Statista shows the estimated share of the UK population with antibodies in the week ending 14 March:

The team behind the government’s contact tracing app has turned its attention to vaccine passports, MPs have been told.

Cabinet office minister Michael Gove on Monday launched a charm offensive to convince sceptical MPs of the need for the certificates, which are controversial with civil liberties campaigners.

Find out more from our Policy Correspondent Jon Stone:

Canada and Berlin’s state hospital groups have stopped giving groups of people under the age 55 the AstraZeneca vaccine, reports of rare but serious blood clots after vaccination mainly in young women.

Canadian health officials said they would stop offering the jab to people under 55 and require a new analysis of the shot’s benefits and risks based on age and gender.

No such cases of serious blood clots, bleeding or death after vaccination have been reported in Canada, where about 307,000 AstraZeneca doses have already been administered.

Deputy chief public health officer Howard Njoo told a media briefing: “We are pausing the use of AstraZeneca vaccine to adults under 55 years of age pending further risk benefit analysis.”

In Berlin, state hospital groups Charite and Vivantes have stopped giving women under the age of 55 the jabs, reported German daily Tagesspiegel.

The newspaper cited a spokesperson for the hospital, adding that around two thirds of staff at Charite have been vaccinated so far and 70 per cent of workers have received one shot of the AstraZeneca vaccine.

AstraZeneca said in a statement it respected Canada’s National Advisory Council of Immunisation’s decision and was working closely with Health Canada’s assessment.

It reiterated that authorities in the UK and the EU, as well as the World Health Organisation, have found the product’s benefits to significantly outweigh the risks across all adult age groups.

Italy is planning to impose a compulsory five-day quarantine for anyone arriving or returning from trips to European Union countries, it has been reported.

Reuters cited sources from Italy’s health ministry, who said travellers will also need to take a Covid test before leaving the country, and another test after the end of their quarantine period.

The sources did not say how long the new measure would remain in place.

West Midlands Police have released footage of an illegal rave held under a bridge on the M6 over the weekend.

The party was found to be in “major breach of coronavirus laws”, and had been held “dangerously close to a river and a motorway”.

Officers were alerted of the event being planned, with party-goers given a “muster point” before the location of the event would be revealed.

The gathering of around 30 people was found underneath the bridge at junction 4 on the border of the West Midlands and Warwickshire, on Saturday.

Officers called in support from a drone and helicopter before moving in on the party, as they were “worried that those gathered may flee and fall into the river, or try to escape onto the motorway”.

£200 fines were issued to 22 people, said a spokesperson.

Assistant chief constable Chris Todd said: “This was an unauthorised event that would have been illegal outside of Covid-19 legislation – but considering the public health context it’s an even more irresponsible act.

“I’d like to thank the officers who attended what was a very challenging scene, late at night, by a motorway and on the banks of a river, acting with public safety as their priority throughout.

“They made sure everyone was safe by closing the motorway for a short period and even helped one woman from the river. Thankfully no one was hurt.

“I understand people’s frustrations at having endured a long lockdown but amassing in large numbers like this for an unlicensed event in such a dangerous environment is not acceptable and we have to take action.”

Separating doses of the Novavax Covid vaccine for more than three weeks – the interval studied in the trial – would “probably” still be effective, an expert for the firm has said.

The jab, which is undergoing assessment by UK regulators, was tested on participants who were given the second dose three to four weeks after the first.

But the UK authorities decided earlier in the year that second vaccine doses would be delayed by up to 12 weeks to get as many people vaccinated with a first dose as possible.

Professor Paul Heath, chief investigator for the Novavax trial in the UK, was asked if the jab would still be effective.

He told Sky News: “The answer is we don’t know because we haven’t looked at studies where the two doses have been separated by more than three to four weeks.

“From basic immunological principles I think it probably would be.”

He added: “We know from other vaccines that we can extend the interval between doses and do so with confidence.

“So if we needed to for this vaccine, I’m sure extending that interval would be fine from the point of view of its effectiveness.”

More than one in two people in England are now thought to have antibodies against coronavirus, according to the Office for National Statistics.

In a sign of the increasing success of the UK’s vaccination programme in protecting the public from the virus, the ONS said it estimated around 55 per cent of the population would test positive for antibodies after a blood test in the week ending 14 March.

Our Health Correspondent Shaun Lintern reports:

A total of 963 deaths registered in England and Wales in the week ending March 19 mentioned Covid-19 on the death certificate, according to the Office for National Statistics (ONS) – the lowest number since the week ending October 16.

The figure is down 36 per cent on the previous week’s total.

Around one in 11 (9.3 per cent) of all deaths registered in England and Wales in the week to March 19 mentioned Covid-19 on the death certificate.

China has given 110.96 million vaccine doses as of 29 March, according to data released by the National Health Commission on Tuesday.

On 29 March, the country carried out about 4.3 million vaccinations against Covid-19.