AMSTERDAM (REUTERS) - The EU's drug watchdog said on Thursday (March 18) it is still convinced the benefits of AstraZeneca's Covid-19 vaccine outweigh the risks following an investigation into reports of blood disorders that prompted more than a dozen nations to suspend its use.

Following are reactions after the European Medicines Agency (EMA) gave an update on its views on the Oxford-AstraZeneca vaccine.

Enrico Bucci, biologist and expert in scientific data analysis at Temple University in the US city of Philadelphia

"The communication disaster of the past few days is unrepairable, so EMA could not today make any possible communication to repair what the governments have done.

"On the other hand, EMA has always said that vaccination should not be interrupted. It is the governments that have made political and emotional decisions. The important thing is, that the EMA today reiterated what it has always said, and which is also what all scientists except a few German scientists have always said: that there is not the slightest significant percentage of cases of thrombosis, and that the vaccine is safe.

"EMA also said other interesting things, such as the possibility that these rare events may be due to previous infections and not to the vaccine."

Jesse Goodman, professor of medicine and infectious diseases at Georgetown University and a former chief scientist director of the Centre for Biologics Evaluation and Research at the US Food and Drug Administration

"When people have cerebral venous clots, among the most common underlying conditions are oral contraceptives and pregnancy."

Goodman also said there are several hereditary and acquired defects in the system that regulates blood clotting.

"It could be when you look at cerebral venous thrombosis that patients often have some unusual predilection to thrombosis, like they were pregnant or had oral contraceptives or some of these were coagulation disorders. My guess is if this ends up being a rare event associated with vaccine, it could be through one of those kind of mechanisms. It could be that it occurs in individuals who perhaps have a predisposition along one of those lines, but I think this is totally speculative at this point.

"I think EMA's position, which is to allow informed immunization while this continues to be investigated is a reasonable assessment of risk and benefit based on the current situation.

"I think transparency and honesty with the public is always the best approach, even though it's often difficult to explain to people."

Professor Andrew Pollard, chief investigator on the Oxford vaccine trial

"I welcome the news that both the MHRA and EMA have reiterated that the vaccine's benefits continue to outweigh any potential risks, and the vaccine should continue to be administered.

"Thousands of cases of Covid-19 are occurring across Europe every day, the rate of covid is rising in many countries on the continent and vaccination remains a central component of our fight against the pandemic virus.

"It is important that public health bodies monitor the roll out of the vaccine, and safety has to be paramount with any new medicine. Importantly, real-world data shows the clear impact of the vaccine on public health - with far fewer cases and hospitalisations from coronavirus in those who have been vaccinated."

Dr Doug Brown, chief executive for the British Society for Immunology

"When developing a new vaccine, the two most important factors are safety and effectiveness. All vaccines have to go through rigorous clinical trials before they are approved for use and they are then monitored during subsequent rollout by the appropriate safety authorities, which in the UK is the Medicines Healthcare products Regulatory Agency (MHRA). The approved Covid-19 vaccines in the UK have all been through this thorough process.

"Over the last few days, a number of countries decided to pause the rollout of the AstraZeneca-Oxford Covid-19 vaccine to double check that having the vaccine is not linked to any cases of blood clots. These reports can sound worrying but we need to put the risk into perspective. As we all know, people fall ill for a multitude of reasons. As has happened in this case, it is right the medicines regulators review the evidence to work out what the cause is behind the rare reports of blood clots and whether it is linked to having been given the vaccine or not.

"We must remember that Covid-19 is a disease that can have serious consequences in its own right, including the development of coagulation problems. In the case of the AstraZeneca-Oxford vaccine, the European Medicines Agency have concluded the vaccine is safe and effective and recommend the continuation of the vaccine rollout, a viewpoint backed up by the UK regulator, the MHRA."

Stephan Lewandowsky, an expert in cognitive psychology at Britain's University of Bristol

Risk management is "a very difficult issue, and different member states and countries may well come to different decisions on it".

"Exercising precaution is one possible way in which policy makers manage risk, and it is more prevalent in European countries than the US or UK, where the emphasis is more on weighing of risks and benefits.

"Given that the European public is generally risk averse, the suspension and careful examination of the cases by the EMA may therefore help maintain public trust in the vaccination process, even though it may also mean that more people will get sick from Covid-19 than if the vaccinations had continued."

Prof Gino Martini , chief scientist at Britain's Royal Pharmaceutical Society

"I hope that any concerns about potential links between the Oxford-AstraZeneca Covid-19 vaccine can now be discarded given the positive verdicts delivered by the EMA, the WHO and the MHRA (UK's Medicines and Healthcare products Regulatory Agency), who have all now said it is safe, effective and can continue to be used. The vaccine is playing a crucial role in protecting vulnerable groups from hospitalisation and death and helping to decrease infection rates across the UK.

"As trusted health professionals, pharmacists are playing a key role in administering Covid-19 vaccinations and have contributed enormously to the success of the programme so far.

We have full confidence in these vaccines and can confidently state that pharmacists can continue administering them to patients. It is so important that we get all those at risk from the virus vaccinated as soon as possible."

Antonella Viola, professor of immunology at Italy's University of Padua

"EMA reiterates that the benefits outweigh the risks... very few cases of thrombosis and in line with what would be expected anyway from the non-vaccinated population. However, they do not exclude the possibility of a link between the vaccine and these rare episodes... and therefore pharmacovigilance will continue.

"So what we have to do is this: we must reassure everyone, these events are extremely rare and the vaccine continues to show a very high level of safety."

Jacques Battistoni, hea dof French doctors' Union MG

"We are delighted with the EMA's announcement which paves the way for a restart of vaccination with the AstraZeneca vaccine in France. General practitioners will be able to do so as soon as Friday if the French government authorises us to do so."