Some trial participants have expressed their concerns over the safety of Pfizer-BioNTech vaccine just days after UK became the first county to begin mass vaccination against the COVID-19. On Tuesday, December 8, the US Food and Drug Administration (FDA) said that the vaccine is safe, as well as effective, and indicated that it could greenlight the COVID-19 jab within days. UK had started vaccination on December 7.

If Pfizer's vaccine is granted an emergency use authorization (EUA), the immunizations—administrated in two doses almost three weeks apart—could start as soon as next week. However, many people have been wondering whether getting this vaccine would be similar to taking a flu shot. According to some trial participants, this vaccine works quite differently than yearly flu vaccines.

Trial Participants' Concerns

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Pfizer Covid-19 vaccine is safe and effective, says FDA Pixabay

One of the Pfizer vaccine trial participants said that after taking the second shot, he woke up with chills and was shaking so hard that he thought he cracked a tooth. The participant also said that "It hurt to even just lay in my bedsheet". There were other participants who experienced headaches and fatigue.

But as per the FDA, the side-effects of the Pfizer shots are common, but there are no safety concerns that would "would preclude the issuance of a EUA".

However, in October, Pfizer gave the COVID-19 vaccine to 100 kids aged between 12 and 15, while the other vaccine developer in the US, Moderna, is expected to start testing in that age group in January 2021. But neither company has announced any plans for the children who are under 12.

Dr. Christian Ramers from Family Health Centers in San Diego said that the immune system of kids is very different from the adults and it behaves really differently compared to others. It means that the testing is critical to identify the right vaccine dose and to see whether there are any unexpected side-effects or not. Since children make up 12 percent of COVID-19 infections, experts believe that a vaccine for them is necessary to control the spread.

A Baltimore County mother said that she doesn't want her kids to be vaccinated "just for the heck of it" until there are more research and testing. "What are the long-term effects with any vaccination but especially in this circumstance they're pushing it so quickly it makes me very nervous".

What About Moderna?

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Covid-19 vaccine Twitter

Another US biotech firm Moderna has also submitted its EUA application. Like Pfizer, Moderna also said that the vaccine could result in side-effects similar to Coronavirus infection symptoms, such as muscle pain, chills and headaches.

A Moderna trial participant, Yasir Batalvi, aged 24, said that when he got the first shot in mid-October, it felt like a flu shot but he experienced stiffness and pain in the left arm where he had gotten the shot, "but it was mild". He also added: "By that evening, I didn't want to move my arm above my shoulder, but it was localized, and it disappeared by the next day".

"I had the same side effects as the first: localized pain and stiffness, but it was a little bit worse," the trial participant recounted the experience after the second injection. But his arm got sore faster and "by the time I got home, I started feeling fatigued and like anyone would feel if they were coming down with the flu". While explaining what he experienced the trial participant said: "I developed a low-grade fever and had chills. That evening was rough."

However, when he called the study doctor, he was told that it was a normal reaction and there was nothing to be concerned about. Later, Moderna stopped testing the highest dose of the vaccine during the trial after receiving several reports of severe adverse reactions. Batalvi said that he is not "too concerned" as it is known now from the vaccine trials that "any adverse events mostly show up in the first couple of months".