Yasir Batalvi, 24, has stiffness in his arms after the first Covid-19 vaccine.

As the United States approaches the licensing of the Covid-19 vaccine, many wonder what it would feel like to be vaccinated.

Pfizer's vaccine in partnership with BioNTech, along with Moderna's vaccine, are currently being applied for emergency approval by the US Food and Drug Administration.

The mRNA vaccine works by giving the body instructions in the form of messenger RNA, to produce a small piece of Sars-CoV-2, namely the mutant protein.

These vaccines require two injections, one first to adapt to the body, followed by a few weeks as a second shot to boost the response.

But because this technology is so new to vaccine production, many people are skeptical and hesitant to use it.

Batalvi recently graduated from college and lives in Boston.

"I feel so helpless. The pandemic has had a huge impact on people's lives. It is not just their life, but their livelihood," Batalvi said.

Batalvi was a bit nervous when he rolled up his sleeve, especially when he was given a 22-page sheet of paper that needed to be signed.

"I think nCoV has caused a huge disruption to our lives, so I decided to do something, this is a civil obligation," Batalvi said.

"Initially, the shot felt like a flu shot, it just left a small mark on the arm," he recalls.

It was after the first dose.

"I actually had some pretty serious symptoms after the second dose. I was fine when I was in the hospital when I finished. But that night was terrible. I started to have a mild fever, fatigue and chills."

Batalvi called the plan doctor to inquire about the symptoms.

"This means your immune system is working hard. You will get well soon," said Dr. Paul Offit, vaccine specialist at Children's Hospital Philadelphia.

"Don't hesitate to go back to getting a second shot, as it will put you in a better position against this terrible virus, which has killed more than 250,000 people and caused many long-term complications."

Anthony Fauci, America's top epidemiologist, said the same thing to Mark Zuckerberg, Facebook's chief executive, earlier this week.

"Others have pain in their arms. Some can have both a cold and painful hand, like the flu and a few people have a fever," he said.

"Most of these symptoms go away within 24 or at most 48 hours," Fauci said, adding it is important to be honest about the side effects that you see.

Scientific advisor Moncef Slaoui, Head of Operation Frequency, the US government's program to promote vaccine research and drug development Covid-19 in cooperation with the private sector, said about 10-15% of subjects participated in the study.

"Most people have less noticeable side effects. I think compared to the 95% protection against either fatal or debilitating infections, this is the right balance."

The side effects encountered by Batalvi should not be confused with safety concerns.

To date, both Moderna and Pfizer vaccines have shown good results, but only time will tell whether any serious unsafety issues will arise over the next few years.

"While we can predict 90-95 percent of side effects occurring within two months of the immune system responding to both vaccines, we have no experience of one or two years of experience.

Batalvi didn't know whether he had a real vaccine or a placebo, but based on his experience, he thought he could guess.

"This is a randomized study. So neither I nor the research doctors nor Moderna know if I have been vaccinated. But based on the side effects I have, I assume I have been vaccinated.

Batalvi said he was looking forward to the end of the pandemic to meet his sister's twin nephews and daughters, who were just born this week.

"I hope that after the vaccine comes in, everyone is confident using it. I tried it and it feels good. I think we can get through it," he said.