Some of the COVID-19 vaccine trial volunteers have reported side effects such as fever, chills and body ache after getting the experimental shots.

Such incidents have been reported from clinical studies being conducted on experimental shots prepared by Moderna Inc. and Pfizer. A total of five participants from two late-stage clinical trials have reported side effects after getting the shots. Three of these participants were from Moderna’s clinical trial while the other two from Pfizer’s late-stage clinical trial.

According to reports, the side effects went away by itself within a day, however, the volunteers were surprised by the fact how severe they were.

“If this proves to work, people are going to have to toughen up,” said one of the woman volunteers, in her 50s, who received the shot as a part of Moderna’s clinical trial. She did not give consent to reveal her identity and requested to remain anonymous.

“The first dose is no big deal. And then the second dose will definitely put you down for the day for sure. … You will need to take a day off after the second dose.”

The volunteer further said that she did not suffer from fever but a severe migraine. It left her exhausted as she was not able to struggle. But she added that even though she felt uncomfortable after getting the shot, the side effects would still outweigh the risks of getting infected by the novel coronavirus.

“My hope is that this works but also that the communication [on side effects] is good,” she said, indicating that Moderna should inform the people getting its experimental mRNA vaccine about the discomfort and advice them to take an off the following day.

Another participant confessed to getting high fever after receiving the shot.

“I wasn’t sure if I needed to go to the hospital or not because 104 is pretty high,” the 20-year-old participant from Maryland said in an interview. “But other than that, it’s been fine.”

Pfizer trial participants also reported similar symptoms.

“If it gets approved, I still think a lot of people should get the vaccine and I hope that all the side effects are made clear up front,” said one of the Pfizer participants, who experienced severe flu-like symptoms after his second shot.

Moderna The Moderna headquarters are seen in Cambridge, Massachusetts on May 18, 2020. - US biotech firm Moderna reported promising early results from the first clinical tests of an experimental vaccine against the novel coronavirus performed on a small number of volunteers. Joseph Prezioso/AFP via Getty Images