As the distribution of the coronavirus vaccine continues across the country, some groups reported experiencing more moderate side effects with the injection.
Although reactions are expected and should not discourage people from getting vaccines, experts say there are some reasons why women, young people and people who have had the coronavirus may be experiencing more side effects.
What side effects are people reporting?
Dr. Albert Ko, professor of epidemiology and medicine at the Yale School of Public Health in New Haven, Connecticut, said that the adverse reactions observed are mostly moderate, with serious “very rare” reactions. Side effects occur at a lower rate than side effects in inoculations commonly used for diseases such as measles, polio, or flu.
Side effects commonly reported include minor symptoms such as sore arms, muscle pain, redness around the injection site and mild fevers. Some people have reported experiencing more side effects after the second dose of Pfizer or Moderna vaccines, and in rare cases, people have had allergic reactions.
Side effects of the vaccine in women
In a recent study conducted by the Centers for Disease Control and Prevention, analyzing safety data from the first month of COVID-19 vaccinations, more than 79% of side effects were reported by women, although only about 60% of doses were administered to women.
Dr. Anne Liu, an infectious doctor at Stanford Health Care in Palo Alto, California, said the rare anaphylactic reactions reported happened “almost exclusively” in women.
“We know that anaphylaxis, which is very rare, appears to be almost exclusively in women,” explained Liu, noting that allergic reactions have been reported in clinical trials and are not a cause for concern. “We don’t know how much of this is reporting bias, as if women, for some reason, report symptoms more often than men.”
A late skin reaction to the Moderna vaccine, reported earlier this month, was seen mainly in women.
Liu said that the immune response in women receiving COVID-19 is different from the response in men who are diagnosed with the virus, which could explain the difference in response to vaccinations.
“Men seem to have worse results (with COVID-19) … Do women generate a slightly more robust immune response? Perhaps this is responsible for some of the differences in side effects,” said Liu, noting that there are differences in male and female immune systems and responses to vaccines, including the flu vaccine. It has been suggested that variable responses may have to do with differences in testosterone and estrogen, but Liu said that link was not firmly established.
Side effects of the vaccine in people who have had coronavirus
Liu said the data from the original clinical analyzes showed that “those who have had COVID have had a little more side effects” compared to people who have not, but said these results “are not so surprising”.
Liu said the different responses are probably related to immune responses. There are two different phases of an immune response. Initially, there is the “new immune response”, which Liu defined as the process of recognizing a substance as dangerous, then recruiting immature memory-forming cells to become mature cells that recognize the specific structure of that substance and then multiplying these mature memories the cells must be ready to react quickly if that substance is found again. This process takes a few weeks, which is why it takes some time to be fully vaccinated.
The second phase is the “recall” or “memory” response, which occurs when the substance is reintroduced into the body. This triggers a faster response to clear the substance before it has a chance to “spread everywhere at high levels and infect many cells”.
Since people who have had the coronavirus have already started the new immune response process, the first dose of the vaccine would be more likely to trigger a recall response. However, people who did not have the coronavirus will have this new immune response with the first dose, then the recall response with the second.
“Instead of (the first dose) generating a new (immune) response, which may be weaker … what you’re seeing is actually a recall response,” said Liu. “This should be faster and, I hope, stronger.”
Side effects of the vaccine in young people
Ko said data from clinical trials indicated that young people reported more side effects after vaccinations. He also saw the differences.
“It is something that I have seen both in terms of relatives who have been vaccinated … as well as the patients I see,” said Ko. “This is certainly on the right track.”
Liu said the difference may be due to changes in the immune system.
“We know that the immune system changes as we age,” said Liu. “We know that younger people (who contract the coronavirus) have a more robust production of a group of molecules called interferons, which is useful in fighting the virus, and that may be part of the reason why the elderly get worse with COVID . .. The more robust response in young people seems to be a good thing and correlates with young people acquiring the coronavirus without a serious infection. “
Liu pointed out that similar effects have been seen in other vaccines, since “many vaccines” are “generally less effective” in older adults. As people age, the human immune system changes in a process called “senescence” that weakens the “initial inflammatory response that responds to danger signals” and reduces the “ability to produce new antibodies”. Liu said that these changes generally mean that older adults receive a different dosage of the vaccine. With respect to the COVID-19 vaccines, no differences in efficacy were observed in older adults.
“Vaccines in general tend to produce less response in older individuals than in young adults,” she said.
How can you respond to side effects?
Both Liu and Ko said that doctors are advising not to take any medication before receiving the coronavirus vaccine, with Ko noting that the premedication did not have “many effects” on the side effects of the flu vaccine.
“We are recommending against premedication, like Tylenol or ibuprofen,” said Liu. “If, after the vaccine, you develop symptoms that can be treated by these drugs, then go ahead and take them, but we are not recommending taking them in advance.”
Liu also said that people who are concerned about side effects may also consider trying to have a lighter workload the day after receiving the second dose of the vaccine, if possible.
Both Liu and Ko emphasized that you don’t need to experience side effects to know that the vaccine worked.
“There is no correlation between feeling symptoms and being able to mount an immune response,” said Ko. “People mount good antibodies regardless of whether they have experienced symptoms or not after vaccinations.”
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