LONDON — After the European Union’s biggest countries suspended the use of AstraZeneca’s vaccine, the continent’s top drug regulator pushed back hard on Tuesday against fears about the shot, saying there was no sign of its causing rare but dangerous problems, and strong evidence that its lifesaving benefits “outweigh the risk of the side effects.”
The reassurance by Emer Cooke, executive director of the European Medicines Agency, came a day after Germany, France, Italy, Spain and others halted use of the vaccine, even as Europe faces a third wave of the virus, hundreds of millions of its people are still constrained by severe pandemic restrictions and many are facing the prospect of rules tightening even more.
The vaccine suspensions were a startling about-face after government officials had spent days assuring the public of the vaccine’s safety. After Germany indicated that it would put the shots on hold, others quickly followed, wanting to present a united front and avoid the political fallout from being an outlier if real problems with the vaccine emerged.
Concerns about possible rare side effects like blood clots and abnormal bleeding have rattled confidence in the vaccine and delayed the already slow and troubled inoculation campaign in Europe. No country in the European Union is on pace to reach its goal of vaccinating 70 percent of its population by September.
The European Medicines Agency was still studying concerns about the ill effects reported in a small number of people who received the AstraZeneca shot, but there was “no indication that vaccination has caused these conditions,” Ms. Cooke said on Tuesday at a news conference.
“While the investigation is ongoing, we are currently still firmly convinced that the benefits of the AstraZeneca vaccine in preventing Covid-19, with its associated risk of hospitalization, outweigh the risk of the side effects,” she added.
Ms. Cooke’s reassurance added to the confusion and mixed messages surrounding Europe’s vaccine rollout. The stakes could scarcely be higher: delaying inoculation for tens of millions of people, though others will continue to receive vaccines made by other companies, and possibly undermining faith worldwide in the AstraZeneca shot.
The AstraZeneca vaccine, developed in partnership with the University of Oxford, was designed to be the workhorse of the global vaccination effort, with some two billion doses ordered for use in more than 70 countries this year.
The European Union’s vaccination efforts have been hindered by political infighting, a supply shortage and a lack of solidarity. And with many countries heavily reliant on the AstraZeneca vaccine, the decision by some to suspend its use while the bloc’s regulatory body looks into safety concerns will slow things down even more.
“AstraZeneca is a very substantial part of the European investment,” said Dr. Don Goldmann, a professor of epidemiology at Harvard’s T.H. Chan School of Public Health. “It is going to be delayed and much harder to have enough of the alternative vaccines to have a coordinated rapid response.”
Clotting problems are relatively common in the general population, and health authorities suspect that the small number of cases reported in vaccine recipients are most likely coincidental.
The governments in Europe that suspended use of the vaccine said they were acting out of an abundance of caution while the bloc’s regulatory body reviewed the data.
The World Health Organization was quick to react, hoping to prevent a broader panic. It said Monday that there was no evidence to suggest that the AstraZeneca vaccine was unsafe.
Millions of people in dozens of countries have received AstraZeneca’s vaccine with few reports of ill effects, and its prior testing in tens of thousands of people found it to be safe.
It is being sold using a nonprofit model and is far cheaper than other vaccines. It can be stored more easily and has already started to be shipped to low- and middle-income countries that signed onto the global vaccine sharing program Covax.
But after a new raft of suspensions on Monday, the only large country in the European Union still administering the shots was Poland, which finds itself already firmly in the grip of a third wave of the pandemic that is moving swiftly across the continent.
The Czech Republic, which in recent weeks has had the highest rates of coronavirus infection and deaths in the world, is also still using the vaccine. Several smaller countries in the bloc have also not suspended it, creating a confused landscape for an exhausted public.
The European Union has ordered 300 million doses of the AstraZeneca vaccine, accounting for some 17 percent of its overall orders, which are divided among six manufacturers.
Andrea D. Taylor, the assistant director of programs at the Duke Global Health Innovation Center, said that even before the pause, the bloc was well behind its goal of vaccinating 70 percent of the population by Sept. 22.
“If you look at the numbers, you can see clearly that they are not on track to meet that goal,” she said. “Even without the pause, I don’t see a scenario where they would have met a 70 percent vaccination rate in September.”
She cautioned that all projections were based on a series of wildly moving targets, including a projected exponential growth in production over the next few months.
With vaccine distribution slowing, governments are turning again to the one tool they have used for the past year: lockdowns. The rules in Europe have been far more restrictive and imposed for far longer than almost anywhere else in the world.
The pain — financial, physical and psychological — is hard to measure but no one doubts it is real and getting worse.
When Italian officials announced a new national lockdown on Monday, the reaction was a mix of anger, resignation, sadness and worry.
Mauro Bolognesi, 65, smoked a cigarette in front of his vintage shop as he looked at the closed shutters around him in the popular Navigli area of Milan.
“I am not going to make it if this lasts one more year,” he said.
“It’s awful,” said Franca Gonella, 65, as she walked her dog in front of the prime minister’s palace in Rome on Monday, one of the few activities Italians are allowed outside the home. “If you are going to lock everyone up then they should be blanketing us with vaccines. The problem is that there are no vaccines.”
While the AstraZeneca vaccine is already authorized in dozens of countries, it has not yet been approved by American regulators. The results from its clinical trial in the United States have not yet been reported, and the company has not sought emergency use authorization from the Food and Drug Administration.
Many public health officials fear that the United States may yet encounter its own new wave of infection caused by more contagious variants, especially as states move to open up completely, eliminating even simple measures like mask wearing requirements. But vaccines are being rolled out with an urgency simply not seen in Europe.
Rossella Crea, 46, a high school teacher in Italy’s northern city of Verona, got her first AstraZeneca shot on March 1. She said that after reading news of the latest suspensions, she became anxious and she was no longer sure she would get her booster dose in May.
“I feel disoriented,” she said, “I think we must get vaccinated in general but this AstraZeneca one worries me.”
In Spain, the suspension came just as some regional politicians were pressing the central government to extend the usage of AstraZeneca’s vaccine to people over age 55.
Some public health experts in Spain are questioning the suspension. In a column published on Tuesday by the newspaper El Mundo, Juan Martínez Hernández, an epidemiologist, described the suspension as “a mistake.”
If such a vaccination program gets halted even when no causal relationship has yet been established, he asked, “are we ready to accept the extension and perpetuation of Covid-19 in Europe and the world?”
While there was broad concern that the decision to halt the use of the vaccine could harden skeptics and embolden antivaxers, many Europeans feared the effects of the suspension more than those of the vaccine.
Jean Imbert, a 70-year-old retiree from Marseille, France, who got his first dose of the AstraZeneca vaccine on March 7, said that he had “no particular concerns” about his shot after Monday’s announcements.
Mr. Imbert said that there was “an overreaction in many European countries,” adding that “if the ban on the vaccine lasts too long, we will have more deaths due to delayed vaccination” than because of inoculations.
Reporting was contributed by Monika Pronczuk from Brussels, Emma Bubola from Rome, Melissa Eddy from Berlin, Raphael Minder from Madrid and Constant Méheut from Paris.