With your first dose of the Pfizer or Moderna vaccine, you may have experienced mild pain in your arm.
But the second dose is gaining a reputation for taking effect. About 40 to 50 percent of people experience symptoms such as fatigue, headache and even chills or fever.
While millions of Californians await their doses, they ask themselves: what is going on? We asked experts.
Q: Why do we experience side effects from vaccines?
ONE: “The ‘reactogenicity’ we see – local and systemic reactions – are short-lived and typically occur between one to three days after vaccination. They are essentially a reflection of the way your body develops immunity. “
• Grace Lee, MD, professor of pediatrics at Stanford University School of Medicine
Q: Why does the second dose cause more problems?
ONE: The first injection teaches your immune cells to recognize the virus; is accelerating. With the second shot, there are more immune cells ready and waiting to launch a major defense. Muscle pain and fever come from inflammation; your immune cells are sending an alarm in the form of chemicals called cytokines.
“Your immune system is ‘primed’ with dose one. You are being “boosted” with dose two. This reflects your body’s quick response. … Your body is seeing it a second time and remembering it, and it is developing the powerful immune response it needs to respond to infection. “
• Grace Lee, MD, professor of pediatrics at Stanford University School of Medicine
Q. What can I do to combat side effects?
ONE. Do not be tempted to skip the second dose. The doses of Pfizer-BioNTech are made 21 days apart; Moderna photos are 28 days apart. Although the first dose provides some protection for about 12 days, you will not be fully protected until two weeks after the second dose.
If possible, schedule the second dose when you can get some rest. If you experience severe side effects, it is safe to take acetaminophen (Tylenol) or ibuprofen (Advil). Ice can help a sore arm. Serious allergic reactions are very rare.
Q: Are there age differences in the response?
ONE: Older adults tend to have a milder response than younger ones because “their immune systems are not responding as vigorously as a young person’s, but they still get 95% protection against the virus.”
• William Schaffner, MD, professor of preventive medicine and infectious diseases at Vanderbilt University School of Medicine
Q: Why not everyone experience them?
ONE: In addition to age, experts do not know why some people have more intense reactions than others.
“Each responds differently. There are actually a number of side effects or reactions and not everyone will have many side effects. And that’s okay because we have data from the trials that show great efficacy even in those that have no side effects. “
• Grace Lee, MD, professor of pediatrics at Stanford University School of Medicine
Q: I felt good after the second dose. Does this mean that I am not protected?
ONE: Think of your education. You can have fond memories of the fun of elementary school. High school or college was more difficult. Both are important.
“Primary vaccination taught the immune system easy things, like in primary school. Sixth grade fractions and all that – they are very easy, but important.
Does this mean that primary education was not really an education, because it did not really cause you pain? Do not.
And then there was a secondary school or university education, which is a little difficult. He went into calculus and physics. Even so, the immune system went through it, and that was really great.
In the end, you had a complete education. This is exactly how vaccines work ”.
• Bali Pulendran, MD, professor of microbiology and immunology at Stanford University School of Medicine
Q: Why don’t other vaccines cause these problems?
ONE: Some do.
“It happens with many, many other vaccines. With the shingles vaccine, people sometimes say, ‘My God, that second injection. I had a fever for a day. ‘
“This is not unique to mRNA vaccines. This is a general feature of any vaccine. “
• Bali Pulendran, MD, professor of microbiology and immunology at Stanford University School of Medicine
Q: If I am exposed to the virus after vaccination, will I also experience these symptoms?
ONE: Unlikely.
“It will depend on how much virus enters your system. If you are exposed, it will enter your nasal passages – and, hopefully, stay there. This is what we call ‘mucosal immunity’. It is a local immune response.
“It is not like that second dose of the vaccine, which is being injected throughout your system, and so the lymph nodes respond. This is a full-body response. “
• Aruna Subramanian, MD, clinical professor of medicine – infectious diseases at Stanford Healthcare
Q: What are “vaccine failures”?
ONE: “We are learning that these two vaccines seem to work very well in preventing serious illness and hospitalization. But in clinical trials, some people have developed symptomatic illnesses. And that is a sign that the vaccine is not working as well as we want. We would love for it to prevent all diseases. “
• Annie Luetkemeyer, MD, professor of infectious diseases at UC San Francisco
Q: Is there any chance that I will become infected after being vaccinated but not showing symptoms?
ONE: “My guess is what we are going to find out about asymptomatic infection – if and when it occurs after vaccination – is that people have only a little bit of the virus around.
“It probably won’t be enough to really set up a robust infection or inflammatory response. I suspect that we will not see ‘long-term’ complications. Whether or not it is contagious to others? This is yet to be seen. “
• Annie Luetkemeyer, MD, professor of infectious diseases at UCSF
Q: After the second dose, for how long do the vaccines provide protection?
ONE: We don `t know yet.
“The data is incomplete because we haven’t had these vaccines in a long time. But the good news is that – in the time we had them and were able to study them – we didn’t really see a significant reduction in immunity levels.
“At the moment, it appears that the ‘half-life’ of antibodies after vaccination is at least one year, and probably more than that.”
• Joel Ernst, MD, professor of medicine and head of the Division of Experimental Medicine at UCSF
Q: Is it likely that we need continuous “booster doses”?
ONE: If necessary, vaccine “boosters” can help in two ways. They can reload the immune response against the original virus. They can also help prevent a new viral variant that can render existing vaccines ineffective. But it is not known if they are needed.
“What we don’t know is exactly what level of antibodies is sufficient to protect us. So there is a lot of monitoring now and an increasing amount of viral sequencing to see what variants are coming up. “
• Joel Ernst, MD, professor of medicine and head of the Division of Experimental Medicine at UCSF