U.S. listed shares of AstraZeneca (AZN) - Get Report slipped on Tuesday after Oxford University paused a study of the drugmaker's COVID-19 vaccine in children until the British regulator completes a review of rare cases of blood clotting.
Shares of AstraZeneca at last check were off 0.6% to $49.23.
Oxford said in a statement that it had not seen any safety issues from the children's trial. But it decided to halt the test because of concern about rare blood-clotting problems reported in multiple countries.
The vaccine researchers are awaiting the results of a review by the British drug regulator Medicines and Healthcare Products Regulatory Agency, “before further vaccinations,” the university said in an emailed statement.
“Whilst there are no safety concerns in the pediatric clinical trial, we await additional information from the MHRA on its review of rare cases of thrombosis/ thrombocytopenia that have been reported in adults, before giving any further vaccinations in the trial,” the university said in its statement.
“Parents and children should continue to attend all scheduled visits and can contact the trial sites if they have any questions.”
The Oxford trial, involving 200 children ages 6 through 17, has been going on since mid-February, according to The Wall Street Journal.
The Oxford-AstraZeneca vaccine in March was deemed safe and effective by both the World Health Organization and the European Medicines Agency.
The British government said last week that it had seen 30 severe blood-clotting cases reported out of 15.8 million administered doses of the AstraZeneca vaccine. Seven of the affected people died.
Last week, AstraZeneca said its COVID-19 vaccine had an efficiency rate of 76%, lower than previously released data from a U.S. trial that were criticized as being outdated.
The U.S. may not need AstraZeneca’s COVID-19 vaccine, even if it wins U.S. regulatory clearance, Anthony Fauci, the nation’s top infectious-disease doctor, told Reuters last week.