As vaccination campaigns against COVID-19 continue and more people receive their second dose, many have reported that it produces more acute side effects than before. But vaccine experts say the news is both general and expected.

“It’s a sign that your immune system is working,” Dr. Williams Moss said Johns is an epidemiologist and executive director of the International Vaccine Access Center at Hopkins.

As of date, more than 35 million vaccines have been administered in the US, and approximately 7 million have received their second and final dose, according to U.S. Centers for Disease Control and Prevention.

Modern and the side effects of vaccines being used in the US developed by Pfizer-BioNotech are common signs that are building up your body’s defenses. CDC Says Flu-like symptoms are expected and may include fever, chills, headaches, muscle aches, and fatigue. Some may have pain and swelling in the arm at the site of injection. All side effects should go away within a few days.

In the vaccine trials for Modern and Pfizer, side effects were higher after the second dose. Moss said some may have little or no symptoms from the first dose, but will feel side effects after the second because their immune system is already primed – resulting in a second acute inflammatory response.

FILE – A woman receives the Pfizer COVID-19 vaccine on February 3, 2021 at an immunization center set up at Trivan College, Illinois. (Photo by KAMIL KRZACZYKI / AFP via Getty Image)

Users of CDC’s tool V-Safe to report the side effects of the T-series, More side effects are reported Within a week of taking his second shot compared to the first.

Mark Susman, who recently received his second dose of the modern vaccine, said he had been feeling ill for about a day and a half.

“Chills, shortness of breath, muscle aches, soreness in general,” Susan Fox 5 is described for DC, The day after receiving his second shot. Sussman said it was not a “full blown flu”, but the side effects lasted for about 36 hours.

But not everyone feels side effects. Sasman’s mother also recently received a second dose of the Pfizer vaccine and felt fine.

How does the COVID-19 vaccine work and why do we feel the side effects?

On the surface of SARS-CoV-2 are spike proteins, viruses that cause COVID-19, which are important for viruses to bind and replicate body cells. All of the developed COVID-19 vaccines serve to induce an immune response against spike proteins, primarily through antibodies.

Modern and Pfizer vaccines being administered in the US are mRNA vaccines. This is a new technique but not unknown, as scientists have been working on the mRNA technique for over a decade.

Instead of injecting the virus, Moss explained that mRNA vaccines work by injecting spike proteins, or a “recipe” for a genetic code, from which cells produce spike proteins.

“Through that mechanism, our own cells produce spike proteins, then what happens is our immune system will look at that protein and recognize it as foreign,” he said, triggering an immune response.

This immune response is broadly known as inflammation, which can result in side effects such as redness, swelling, and tenderness at the injection site. It can also mean extensive systemic reactions in the body, such as fever, headache, muscle aches, joint pain, or fatigue.

“A lot of things happen in relation to inflammation, but it’s actually a sign that our immune system is recognizing that there is a foreign protein in our body and preparing to fight and get rid of it,” Moss said.

Why may some more side effects be felt after the second dose?

As part of the body’s immune response, it forms memory cells known as T-cells and B-cells. If a virus or foreign substance re-enters our body, such as a second dose of the mRNA vaccine, it is a reminder to the immune system.

“Basically, this second dose is saying, ‘Hey, I know you saw this spike protein a month ago. I’m going to remind you once again what it looks like so that you can actually make this Prepare to attack, ”Moss. Explained.

Modern and Pfizer vaccines are two doses, 28 and 21 days apart, respectively.

The first dose of the vaccine increases the immune system, forming an army of cells. As a result, Moss said that the second dose then produces a larger immune response – hence the potential for stronger side effects.

“We have many more cells available to attack this,” Moss explained. “But that’s why inflammation can become more severe with the second dose because our immune system is already primed, so you get an even more intense inflammatory response.”

Does the vaccine still protect you if side effects are not felt?

While the side effects are usually a sign that the body’s immune system is functioning, those who feel fine after being vaccinated are definitely protected.

“People who do not have moderate or severe side effects from the vaccine may still have a very protective immune response. They do not have, for various reasons, a profound inflammatory response,” said Moss. Combination. Prior history of exposure.

Why is the second COVID-19 dose so important?

Two-shot doses from Pfizer and Modern have been shown in clinical trials to be 94% or 95% effective at preventing symptoms of COVID-19. Although there is some protection afforded by a single dose, the safety may be significantly lower, although it remains unclear.

In January, the US Food and Drug Administration Said Increasing the length of time between doses or skipping the other altogether will not “solidify prematurely and in available evidence.” The agency reiterated the importance of continuing the two-dose diet in the study at 21-day and 28-day intervals.

Dr. Anthony Fauci, the government’s top infectious disease specialist, too Clarified this week The US will “go by science” from its clinical trials and continue its second dose of Pfizer-Bayonet and Modern vaccines within the recommended timeframe.

Fauci was responding to a debate strategy used by the UK to delay the second shot so that it could protect more people with the first dose. Pfizer, one of the two approved vaccines in the country, has not supported the decision to elapse between doses.

More than 458,000 Americans have died of the virus compared to World War II. Some 27 million people in the US have contracted it, some even more serious, Long term complications.

“I often say, the fundamental problem for most people … is they are reducing the risk of the disease and reducing the risk of the vaccine,” Moss said. “A day or two of restlessness is, in my view, a worthwhile trade for disease prevention.”

related: The NFL offers Biden all stadiums as vaccine sites

This story was told from Cincinnati.