Participants in U.S. vaccine clinical trials experienced mild to moderate side effects

Pfizer, the U.S. pharmaceutical company, said Friday that participants in the company's new crown vaccine clinical trials experienced mild to moderate side effects.
Pfizer made the comments at an investor conference on The 15th, Reuters reported Thursday. Side effects of the participants included fatigue, headache, chills and muscle pain, fever in some people, and even high fever. The data comes from a double-blind trial, which means Pfizer doesn't know who was vaccinated and who was given a placebo.
Pfizer's chief scientific officer, Mikael Dolsten, said at an investor conference that Pfizer's vaccine trials are not currently reporting safety issues, Bloomberg reported Thursday. Pfizer says fatigue is by far the most common side effect of the trial.
Pfizer's vaccine, developed in collaboration with Germany's BioNTech, plans to conduct a vaccine trial involving 44,000 volunteers, which has so far recruited more than 29,000 people and given a second dose of the vaccine to more than 12,000 volunteers. Pfizer expects to get test results on the vaccine's effectiveity in October.
, British pharmaceutical company AstraZeneta suspended a vaccine trial developed in collaboration with Oxford University after volunteers developed "unseplained" illnesses. The vaccine trial resumed in the U.S. and Brazil on The 14th, but is still suspended in the U.S., Reuters reported.