Extensive maintenance: Expert explains how COVID-19 vaccines work and side effects after shots
Dr. Williams Moss, an epidemiologist and executive director of the International Vaccine Access Center in Johns Hopkins, explains how mRNA vaccines work through Pfizer and Moderna and why side effects are more likely after the 2nd dose.
As the vaccination campaign against COVID-19 continues and more people receive their second dose, many have reported that it has caused more serious side effects than after the first. But vaccine experts say this news is normal and also expected.
“It’s a sign that your immune system is working,” said Dr. Williams Moss, an epidemiologist and executive director of the International Vaccine Access Center in Johns Hopkins, said.
To date, more than 35 million vaccines have been administered in the U.S., and nearly 7 million have received their second and final dose, according to the U.S. Centers for Disease Control and Prevention.
Side effects of the vaccines used in the USA, developed by Moderna and Pfizer-BioNtech, are normal signs that your body is offering protection. The CDC says flu-like symptoms are to be expected and can include fever, chills, headaches, muscle aches and fatigue. Some have pain and swelling in the arm at the site of injection. All side effects should go away within a few days.
In vaccine trials for Moderna and Pfizer, side effects were more frequent after the second dose. Moss said some people had minimal or no symptoms from the first dose, but that they would experience side effects after the second because their immune system was already replenished, resulting in a more intense inflammatory response the second time.
FILE – A woman receives a Pfizer COVID-19 vaccine at a vaccination center located at Triton College in River Grove, Illinois, on February 3, 2021. (Photo by KAMIL KRZACZYNSKI / AFP via Getty Images)
Users of V-safe, the CDC’s tool to report vaccine side effects, reported more side effects compared to the first within a week of receiving their second chance.
Mark Sussman, who recently received his second dose of the Moderna vaccine, said he had been ill for about a day and a half.
“Chills, shortness of breath, muscle aches, general aches,” Sussman described to FOX 5 DC, days after receiving his second shot. Sussman added that it was not a “full-blown flu” but that side effects were present for about 36 hours.
But not everyone feels side effects. Sussman’s mother also recently received a second dose of Pfizer vaccine and is feeling well.
How does the COVID-19 vaccine work and why do we feel side effects?
There are peak proteins on the surface of SARS-CoV-2, the virus that causes COVID-19, which are critical for the virus to bind to and replicate in the body’s cells. All of the developed COVID-19 vaccines work to elicit an immune response against the protein, primarily through antibodies.
The Moderna and Pfizer vaccines administered in the US are mRNA vaccines. This is a new technology, but not unknown, as scientists have been working on mRNA technology for more than a decade.
Instead of injecting the virus, Moss explained that mRNA vaccines work by injecting a ‘recipe’ for the ear protein, or the genetic code, that causes cells to produce the ear protein.
“Through the mechanism, our own cells will produce the peak protein. What happens then is that our immune system will see the protein and recognize it as foreign,” which triggers an immune response, he said.
This immune response is commonly known as inflammation, which can cause side effects such as redness, swelling and tenderness at the injection site. It can also mean a broader systemic reaction in the body, such as fever, headache, muscle aches, joint pain or fatigue.
“A number of things happen with regard to inflammation, but it’s really a sign that our immune system realizes that there’s a foreign protein in our body and is preparing us to fight it and get rid of it,” Moss said.
Why can some people experience more side effects after the second dose?
As part of the body’s immune response, it builds memory cells known as T cells and B cells. When a virus or foreign substance enters our body again, such as the second dose of the mRNA vaccine, it is a reminder to the immune system.
“Actually, the second dose says, ‘Hey, I know you saw this ear protein a month ago. I’m going to remind you again what it looks like, so you’re really ready to attack it,'” Moss explains.
The Moderna and Pfizer vaccines consist of two doses, 28 and 21 days respectively.
The first dose of the vaccine makes the immune system primary and creates an army of cells. As a result, Moss said that the second dose then generates a greater immune response – hence the possibility of stronger side effects.
“We have a lot more cells available to attack it,” Moss explained. “But that’s why the inflammation can be worse with the second dose, because our immune system is kind of already prepared, so you get an even more intense inflammatory reaction.”
Does the vaccine still protect you if you do not experience any side effects?
Although side effects are usually a sign that the body’s immune system is working, those who feel well after receiving the vaccine are definitely protected as well.
“People who do not have moderate or severe side effects from the vaccine may still have a very protective immune response. For various reasons, they just did not have that intense inflammatory response,” Moss said, referring to a combination of genetics. and previous history of exposure.
Why is the second dose of COVID-19 so important?
The two-shot dose of Pfizer and Moderna shown in clinical trials is 94% or 95% effective in preventing COVID-19 symptoms. Although a single dose provides some protection, the protection may be significantly shorter, although it remains unclear.
In January, the U.S. Food and Drug Administration said extending the time between doses or skipping the second total was “premature and not firmly rooted in the available evidence.” The agency reiterates the importance of continuing the two-dose regimen at intervals of 21 days and 28 days.
Dr Anthony Fauci, the government’s top expert on infectious diseases, also made it clear this week that the US will “approve” the clinical trials and administer the second doses of the Pfizer-BioNTech and Modern vaccines within the recommended period.
Fauci is responding to a debated strategy that the UK used to delay the second survey so that it can protect more people quickly with a first dose. Pfizer, one of two vaccines approved in the country, does not endorse the decision to split the time between doses.
Fauci says the US should stick to the current 21-day and 28-day intervals for Pfizer, Moderna
Dr Anthony Fauci said the US should stick to the data showing the best results by increasing the Pfizer vaccine to 21 days and Moderna to 28 days, despite studies by AstraZeneca on extending the interval.
More than 458,000 Americans died from the virus, a death toll higher than in World War II. Nearly 27 million people in the U.S. have contracted it, some even having serious long-term complications.
“I often say, the fundamental problem for most people … is that they underestimate the risk of the disease and overestimate the risk of the vaccine,” Moss said. “A day or two of discomfort is, in my opinion, a valuable compromise to be protected from the disease.”
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This story was reported from Cincinnati.