The temporary suspension of the Oxford/AstraZeneca coronavirus vaccine in European countries could have significant implications for vaccine confidence in the UK and even delay Boris Johnson’s “unlockdown”, scientists have warned.

Experts say the disruption to the vaccine rollout in Europe will “undoubtedly” increase the chances of a new, more dangerous Covid-19 variant emerging that could escape current vaccines.

On Monday, France, Germany, Italy and Spain joined other smaller European countries in pausing the rollout of the Oxford/AstraZeneca jab following reports of blood clots in some patients.

The World Health Organisation (WHO) and the UK – alongside many experts in Europe – have insisted there is no evidence of a link and have urged countries not to pause their vaccinations.

The European Medicines Agency (EMA) – the European Union’s medicines regulator – is currently reviewing the data and will release its findings on Thursday. It has said there is no evidence at present of clots linked to the vaccine. 

But by the time the EMA comes to a conclusion the damage may have already been done in those countries, worries Professor James Chalmers, a molecular and clinical medicine expert at the University of Dundee.

“Some members of the public will not look into this in enough detail,” he tells HuffPost UK. “They will just see the headlines that regulators in multiple countries have got concerns about the vaccine and that in turn will put doubt in people’s minds about the safety of the vaccine – when those doubts are completely unfounded.

“At a time when places like Italy are experiencing really significant waves and desperately need to get vaccines rolling out as quickly as possible, by the time the regulators have already looked into this and concluded there is no problem, they will have caused substantial damage in the intervening period by slowing down the vaccine rollout and in undermining public confidence.”

According to Professor Christina Pagel, head of clinical operational research at University College London and a member of Independent Sage, vaccine hesitancy has long been an issue in Europe – even before recent events. Both France and Germany have seen reports of thousands of discarded vaccines because of low takeup. 

“AstraZeneca has had an image problem in Europe which wasn’t helped by what happened in January,” she tells HuffPost UK, referring to the row between the pharmaceutical giant and the EU earlier this year. 

“There are also much higher levels of vaccine hesitancy there than we have in the UK: about 50% of the French population said they weren’t going to get vaccinated. So anything that adds fuel to that fire is problematic.”

The main concern is if these fears begin to make their way over to Britain, she says. “In Europe, they’re not relying on AstraZeneca for their vaccination programme, because they have fewer doses and have other vaccines. I think it could have the potential to have a bigger impact here, where we going through five million doses a week and they are almost all from AstraZeneca.”

“Anything that makes people worried and more suspicious that the [UK] government is trying to cover things up – that’s a serious problem. We don’t have a lot of trust in our government as a population, so if there’s any kind of hint that other countries were right to suspend [the vaccine] then we could lose more trust – not just in AstraZeneca but in other Covid vaccines as well.”

Chalmers also worries about the impact of a drip-feed of negative headlines and misinformation about the vaccine.

“Every time there’s a statement from the French or German government, it puts more doubt into people’s heads and this could start to impact the uptake of the vaccine here,” he says.

With almost 25 million people in the UK having received their first dose of a vaccine, it is hoped that all over-50s – the last of the first nine priority groups – can expect to be vaccinated in the next few weeks. Chalmers adds: “I would argue that we’ve done the easy bit first, which is persuading the people most vulnerable to the virus. If you’re over 80 and you know your risk is really high, then it’s not a difficult decision. Even if there are risks, you’re going to take it.”

The impact of vaccine fears is more likely to affect younger adults, who do not see themselves at high risk.

“They could be more concerned about things like blood clots or fertility or those bits of misinformation that are flying around,” says Chalmers. “This the group I’m worried about and I’m concerned that it could be quite significant.”

A drop in the take-up of the Oxford/AstraZeneca vaccine among these groups could risk disrupting the country’s entire vaccination programme and force us into a longer lockdown, he adds. “We need to achieve very high levels of vaccination to reach any level of herd immunity. It doesn’t actually take a lot of the population to say no to the vaccine to put the entire thing at risk.

“If we allow the virus to run through the younger population at really high numbers, we’re taking a huge risk that we get a new variant emerging that could have reduced effectiveness against the vaccine, like the ones in South Africa or Brazil. 

“The decisions that have been made this week undoubtedly will have increased the likelihood of the emergence of new variants,” he adds.

If this were to happen, the government would have little choice but to reverse the easing of lockdown restrictions and shut things down. “At the moment, the biggest risk that would stop us from getting back to normal by late summer is the emergence of a vaccine-escaped variant. That’s why we need to be very cautious when lifting the current restrictions, but also why we need very rapid and complete vaccine uptake.” 

Martin McKee, professor of European Public Health at the London School of Hygiene and Tropical Medicine, said he was not too concerned about the potential impact of the suspension on the vaccine rollout in the UK.

“So far the evidence suggests that it is not having an appreciable impact on uptake here but we need to wait and see,” he told HuffPost UK.

“The general view among my colleagues across Europe is that, while understanding that some regulators want to be seen to be very cautious because of the need to reassure the public, the evidence available at present does not give cause for concern.”

But Pagel worries the UK’s path out of lockdown is now in jeopardy if hesitancy over the Oxford/AstraZeneca vaccine affects take-up. “The vaccine is doing the heavy lifting of controlling the pandemic, but if in mid-April we’re still at 5,000 cases a day (as we are currently at) then that’s an issue,” she says.

“There’s a plausible path to [the lifting of lockdown] going really well, but there’s also a plausible path to it going badly and we don’t know yet what’s going to happen.” With the inevitable rise in cases from the reopening of schools and businesses, vaccine hesitancy could derail any hopes of June 21 as “the end of lockdown”.

“One of the tests of coming out of lockdown is that the vaccination programme is successful,” she continues. “We need a high proportion of vaccinated people to have any chance of staying open, so the longer it takes to get there the harder it will be to open up.”

Although outdoor activities such as tennis and pub gardens may be permitted as planned, Pagel warns the timetable of opening up indoor spaces could be severely affected: “In terms of places like indoor restaurants and theatres that are scheduled to open in mid-May, I can easily imagine that ending up being pushed back to July or August.

“That’s if something goes badly wrong. Right now we’re at a point where we know there’s a cliff edge and it’s really foggy, so we don’t know how far away we are from that edge.” She said her initial response to hearing Monday’s reports about European countries pausing the vaccine was that was “bats**t crazy”. 

“I just couldn’t understand it at all. Given that many European countries are facing a third wave with the potential for more lockdowns and more deaths, yet we’ve seen that the AstraZeneca vaccine has worked really well in the UK. It’s working and it’s even more effective than we had thought.”

“I think this is a serious mistake on their part,” Chalmer says. “I’m really, really surprised. For one, the numbers show there is no evidence at all to show the complications are due to the vaccine. It seems like it was a very rash and overly cautious decision to stop the vaccine rollout.”

Professor Stephen Reicher, a member of the government’s Scientific Pandemic Insights Group on Behaviours (SPI-B), argues that we shouldn’t diminish people’s ability to understand and make sensible judgements about the vaccine. “During this pandemic, we’ve underestimated the public in all sorts of ways and I think we’re doing it again,” he tells HuffPost UK.

“I think people recognise that nothing in this world is 100% risk-free and that while it is absolutely true that no vaccine is perfect, the risks of not being vaccinated are far greater than from the vaccine.”

The key lies in messaging, Pagel says: “Transparency is the best policy. The way to get trust from the public is to be open and present the information on both sides. People will be able to understand the information and understand why the balance of risks means it is very much skewed in favour of taking the vaccines.” 

Chalmers agrees. “The government and public health officials need to be constantly reassuring the public that it has absolute confidence in the safety and efficacy of the vaccine,” he says. “And that the confidence is based on this amazing and indisputable data.”

“These countries will argue that they are taking any reports of concern over side effects seriously, rather than just brushing things under the carpet,” Pagel adds. “The question is: does investigating [these fears] and concluding it’s fine actually reassure people or not?

“Ultimately it’s about how much trust people have in the system, how much they believe the regulators and how it feeds into the general public’s feelings about how the pandemic is going.”