The company confirmed the decision in a statement on Tuesday afternoon.
Rare cases of blood clots combined with low platelet numbers in persons who have received the vaccine are the background for the decision, the company said.
“We have made the decision to proactively delay the rollout of our vaccine in Europe,” Johnson & Johnson said in the statement.
“We have been working closely with medical experts and health authorities, and we strongly support the open communication of this information to healthcare professionals and the public,” it added.
According to the company, the United States Centers for Disease Control (CDC) and Food and Drug Administration (FDA) are reviewing data “involving six reported US cases out of more than 6.8 million doses administered”.
“Out of an abundance of caution, the CDC and FDA have recommended a pause in the use of our vaccine” in the United States, it said.
Vaccination programmes in several European countries could be impacted by the decision to delay rollout of the vaccine, which is also known as the Janssen vaccine after the Johnson & Johnson subsidiary which developed it.
France was scheduled to receive its first 200,000 doses of the Janssen vaccine this week. The vaccine has already been authorised for use on all age groups by French medical regulator Haute autorité de santé.
France’s rollout had been planned primarily through family doctors and pharmacies, while mass vaccination centres continue to rely more heavily on Pfizer and Moderna.
Nordic countries Sweden, Denmark and Norway were also due to receive their first doses of the Johnson & Johnson vaccine later this week, while the first delivery was received in Austria on Tuesday morning.
Sweden will decide how to use the vaccine within the coming days, the country’s health agency Folkhälsomyndigheten said earlier on Tuesday.
“We are looking at the issue and the data available from the European Medicines Agency and our American colleagues,” Sweden’s state epidemiologist Anders Tegnell said at a briefing, adding a decision would be announced “within one or a few days.”
Each of the Nordic countries has factored large-scale deliveries of the Johnson & Johnson vaccine into their vaccination calendars.
Sweden expected to receive 67,000 doses of the Janssen vaccine in April, a reduction on the 229,000 doses previously expected. Another 295,000 doses were set to arrive in May, and another 888,000 by the end of June.
Denmark has ordered more vaccine doses from Johnson & Johnson than from any other supplier, having earmarked 8.2 million doses. Those doses were scheduled to begin arriving from Wednesday.
“It is very important for us… before we initiate use in Denmark, to ascertain whether we, for example, need further documentation and scientific research, whether there should be certain provisions for use, whether it should be used (only) for certain target groups,” the director of the Danish Health Authority (Sundhedsstyrelsen) Søren Brostrøm told news wire Ritzau in a written comment.
Norway’s programme for vaccinating its population faces a setback of delays of up to 8-12 weeks if the country does not use the Janssen vaccine and also chooses not to reimplement the AstraZeneca vaccine, which remains suspended in the country, also due to concerns over side effects.
The estimate was given by department director Line Vold of the Norwegian Institute for Public Health (Folkehelseinstituttet) at a briefing on Tuesday afternoon.
“If both AstraZeneca and Johnson & Johnson are excluded, vaccination can be completed 8-12 weeks later provided other vaccines are delivered as promised,” Vold said.
Austria, which ordered 2.5 million doses of the vaccine for a population of 8.5 million, plans a heavy reliance on the Johnson & Johnson vaccine.
On Tuesday morning, the first delivery of around 16,800 doses of the vaccine arrived in Austria.
Austrian health authorities indicated that a plan to start administering the doses immediately would be temporarily suspended.
“Until there is clarity about any side effects, these doses will not be delivered to the vaccination centres and will not be administered,” said a spokesperson for the Ministry of Health on Tuesday.