SAN FRANCISCO -- One of the front-runners in the quest for a COVID-19 vaccine is reporting hopeful news.
Pfizer says its vaccine is proving to be safe during phase three trials.
RELATED: Oxford, AstraZeneca to resume coronavirus vaccine trial after pause due to patient's reported side-effect
About 6,000 participants have complained of side effects, but all of those were minor and included headaches and sore arms.
Pfizer is studying more than 44,000 people of all ages. This in an increase from 30,000 that they announced on Saturday.
RELATED: US says it plans to provide free COVID-19 vaccine to all Americans
The data they released on Tuesday shows that this decision was made because of the safety of the first phase of testing.
According to the study, "These results support selection of the BNT162b2 vaccine candidate for Phase 2/3 largescale safety and efficacy evaluation, currently underway."
The company expects to have data on the effectiveness of the vaccine in October.
Coronavirus: Pfizer vaccine trials report promising results