(Reuters) – Pfizer Inc. PFE.N said Tuesday that participants mostly showed mild to moderate side effects when given either the company’s experimental coronavirus vaccine or placebo in an ongoing study at a late stage.
The company said in a presentation to investors that side effects included fatigue, headaches, chills and muscle aches. Some participants in the trial also developed a fever ̵
Kathrin Jansen, Pfizer’s head of vaccine research and development, stressed that the independent data monitoring committee “has access to blind data, so they will let us know if they have security issues and have not done so to date.”
The company has enrolled more than 29,000 people in its 44,000-volunteer trial to test the experimental COVID-19 vaccine it is developing with German partner BioNTech. 22UAy.F.
Over 12,000 participants in the study had received a second dose of the vaccine, Pfizer executives said during an investor conference call.
The comments follow rival AstraZenecas AZN.L COVID-19 vaccine trials were put on hold worldwide on September 6 after a serious side effect was reported in a UK volunteer.
AstraZeneca’s lawsuits resumed in the UK and Brazil on Monday following a green light from UK regulators, but remain on hold in the US.
Pfizer expects it is likely to have results on whether the vaccine works in October.
“We believe – given the very robust immune profile and also the preclinical profile … that vaccine efficacy is likely to be 60% or more,” said Pfizer’s Chief Scientific Officer Mikael Dolsten.
Reporting by Manas Mishra in Bengaluru and Michael Erman in Maplewood, NJ; Edited by Arun Koyyur, Shounak Dasgupta and Aurora Ellis