MADRID, Sept 15 (Reuters) - News of serious side effects in one participant of AstraZeneca's COVID-19 vaccine trial led some volunteers in Johnson & Johnson's vaccine trial in Spain to drop out, its lead investigator told Reuters on Tuesday.
Still, the trial had sufficient reserve volunteers to carry on as normal, lead investigator Alberto Borobia said.
"Many have called to ask us some more detail about the risk of the vaccine, whether what happened with that vaccine had anything to do with the one we are studying, these types of questions," Borobia said in the interview. He did not say how many people had dropped out.
This highlights the challenge for drugmakers in trialling potential vaccines to control the pandemic in enormous public scrutiny. Drugmakers often pause trials while testing drugs but they do not typically disclose that.
AstraZeneca's COVID-19 vaccine trial was placed on hold globally on Sept.6 after a serious side effect was reported in a trial participant in the UK.
Trials restarted in Britain and Brazil on Monday with the go-ahead from British regulators, but remain on hold in the United States.
Johnson & Johnson's Belgian Janssen unit began Phase II trials of its COVID-19 vaccine in Spain on Monday, to be carried out on 190 people and concluded on Sept. 22.
Trials are also being carried out in the Netherlands and Germany, coming to 550 participants in total. (Reporting by Silvio Castellano, Michael Gore, Writing by Victoria Waldersee Editing by Ingrid Melander)