Germany, France, Italy and Spain are suspending use of AstraZeneca‘s coronavirus vaccine amid concern over reports of blood clots linked to the jab, despite assurances from the drugmaker and regulators that there is no link with coagulation disorders.

Scientists and experts have reacted with concern to the decision, insisting there is no current evidence to suggest the jab is responsible for the 37 “thromboembolic events” that have so far been recorded among more than 17 million recipients of the vaccine.

AstraZeneca said the incidence of clots is much lower than would be expected to occur naturally in a general population of this size and is similar to that of other licensed Covid-19 vaccines.

The European Union’s own regulator is continuing to advocate use of the vaccine, as is the World Health Organisation, while the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) urged people to “still go and get their Covid-19 vaccine when asked to do so”.

Earlier on Monday, Boris Johnson defended the vaccine after being asked if he could tell the public that the jab was safe.

“Yes, I can,” he said. “In the MHRA we have one of the toughest and most experienced regulators in the world. They see no reason at all to discontinue the vaccination programme … for either of the vaccines that we’re currently using.”

A Downing Street spokesperson said that the PM intended to take either the AstraZenecea or Pfizer jab when offered a first dose.

Professor Anthony Harnden, deputy chairman of the joint committee on vaccination and immunisation (JCVI), also sought to reassure the public and said people should attend their vaccine appointments.

He told BBC Breakfast: “We will keep monitoring this and if there is any safety signals that we are concerned about, we would let the public know straight away.

“At the moment, the message is absolutely clear – go and get your vaccine when offered.”

The European Medicines Agency (EMA) meanwhile said that “many thousands of people” develop blood clots every year in the EU and “that the benefits of the AstraZeneca vaccine in preventing Covid-19, with its associated risk of hospitalisation and death, outweigh the risks of side effects”.

The EMA’s safety committee is reviewing the data on the blood clots and working closely with the AstraZeneca, experts in blood disorders, and authorities including the MHRA.

The committee will further review the information on Tuesday ahead of an extraordinary meeting on Thursday to consider any further actions that may need to be taken.

Germany said it was suspending its use of the AstraZeneca vaccine as a “precaution” and on the advice of its national vaccine regulator, the Paul Ehrlich Institute, which called for further investigation of the cases.

A spokesman for Germany’s Federal Ministry of Health said the EMA would decide “whether and how the new information will affect the authorisation of the vaccine”.

French president Emmanuel Macron said France was also suspending use of the vaccine as a precaution.

“The decision which has been taken out of precaution is to suspend vaccinating with the AstraZeneca vaccine in the hope that we can resume quickly if the EMA gives the green light,” Mr Macron told a press conference. “We are therefore suspending its use until tomorrow afternoon.”

The Italian medicines authority AIFA also confirmed it was taking the decision as a “precautionary and temporary measure”.

Italy’s decision to suspend use of the vaccine was made after a discussion between the country’s prime minister, Mario Draghi, and health minister Roberto Speranza.

“[Mr] Speranza held talks with the health ministers of Germany, France and Spain during the day,” the health ministry statement said.

The decision follows similar moves by the Netherlands and Ireland in the last 24 hours to allow time to investigate cases of blood clots that occurred after vaccination.

But the overwhelming scientific opinion remains that there is no certain link between blood clots and the vaccine, and the reported cases could easily be coincidental.

The head of Oxford University’s vaccine group, Andrew Pollard, said there was “very reassuring evidence that there is no increase in a blood clot phenomenon here in the UK, where most of the doses in Europe have been given so far”.

AstraZeneca said a review of safety data from more than 17 million people vaccinated in the EU and UK had shown “no evidence of an increased risk of pulmonary embolism, deep vein thrombosis (DVT) or thrombocytopenia, in any defined age group, gender, batch or in any particular country”.

Until earlier this month Germany had restricted the AstraZeneca jab to people aged under 65 because of what it said was limited evidence to prove its efficacy in older cohorts.

On 4 March, Germany’s vaccination committee reversed that guidance, opening the vaccine up to most of its adult population.

Norway, Iceland, Bulgaria, Ireland and the Netherlands have also opted to halt the rollout of all doses produced by the Anglo-Swedish pharmaceutical company.

Austria, Estonia, Latvia, Lithuania and Luxembourg have suspended the use of a certain AstraZeneca batch, while Italy and Romania stopped the use of another batch.