COVID-19 Vaccine: Your Questions Answered

arm swelling covid 19 vaccine

The FDA has now authorized three COVID-19 vaccines. Both of the first two authorized vaccines rely on an immunity-building strategy that hasn’t been used in any other vaccine. As many of us start rolling up our sleeves to get a shot, here are answers to some of the most frequently asked questions.

What is mRNA? Why does it matter?

All previous vaccines have been based on weakened virus molecules or proteins from the disease (pathogen) that our immune systems can easily overcome while learning to recognize it. The new vaccines from Moderna and Pfizer — the first two to make it to market so far in the U.S. — contain mRNA (messenger RNA), which is a genetic template that instructs our cells to build the viral proteins that our immune systems can then recognize. Its main perk is that by allowing our bodies to produce the proteins (rather than growing them in a lab like in traditional vaccines), it slashes the time it takes to produce the vaccine (as done in the past) in the lab. For nearly 20 years, researchers have been interested in using mRNA in vaccines. Some were even tested in early clinical trials for rabies, influenza and Zika. However, the vaccines for COVID-19 are the first mRNA vaccines ever authorized by the FDA. This long history of studying the mRNA concept is why the vaccine could be developed so quickly. mRNA is new to you and me, but a well-known process to scientists.

Will the COVID-19 vaccine change my DNA?

mRNA is a messenger in your body. It’s the way your DNA tells the rest of your body what proteins to create for various functions. In your body, mRNA is created in the nucleus of your cells, based on the DNA that resides there. Then the mRNA exits the nucleus to be used as a template for protein-making in the rest of the cell, and it has no way back in. Soon, it degrades without ever re-entering the nucleus or coming in contact with DNA. mRNA lives in the body between a few hours and a couple of days.

Like naturally occurring mRNA that has already left the nucleus of your cells, the mRNA vaccine isn’t able to enter your cell’s nucleus. Because of that process, it can’t come in contact with or change your DNA. Click here to see  a video that explains the process more fully.

The Johnson & Johnson vaccine uses a viral vector — a harmless virus-turned-delivery system that’s been used in vaccines before — to introduce the gene that encodes a protein found on the surface of the COVID-19 virus. Our cells then create just this protein (not the whole COVID-19 virus) so our immune systems learn to recognize it. It also will not change your DNA.

Why do I need two shots of the Pfizer or Moderna vaccines?

Multiple doses of the vaccine expose our immune systems to more of the viral proteins, giving it the chance to develop more antibodies and protection. The immunity takes time to develop. Researchers believe that 10 days after the first dose, patients develop about immunity that is 52% effective. About a month after receiving their second dose, immunity can reach 94%. A similar strategy is used for other vaccines, like Shingrix, developed to prevent shingles.

Since the initial assessment, new analysis of the research suggests that two weeks after the injection, a single dose of Pfizer or Moderna’s vaccines is more protective than previously thought, potentially up to 92%.

How does the FDA decide if a side effect is severe?

The FDA has a toxicity grading scale to rate adverse events related to preventive vaccines. It ranks both local events (like injection site pain) and systemic events (like fever and nausea) as mild (Grade 1), moderate (Grade 2), severe (Grade 3) or life- threatening (Grade 4.) Several effects, like pain at the injection site, headache, fatigue and nausea, are considered Grade 1 if they do not interfere with your activity at all. If side effects do prevent you from doing ordinary tasks, they may be designated Grades 2 or 3. If the symptoms cause you to go to the emergency room for treatment, they are Grade 4.

Is the COVID-19 vaccine safe?

The most common side effects for all three vaccines — headache, fatigue, fever, chills and muscle and joint pain — are more intense than those for the flu, for example. And the side effects caused by the COVID-19 vaccine tend to be worse after the second shot than the first.

The FDA reported that up to 4.6% of Pfizer vaccine patients, 9.6% of Moderna’s patients, and 2% of Johnson & Johnson’s patients experienced severe (Grade 3) adverse effects. Grade 3 effects are those serious enough to interrupt a person’s life — for example, by causing them to take a day off of work — but not so severe that the person is hospitalized. Younger patients were more likely than older ones to experience severe adverse effects. No life-threatening effects were linked to the Pfizer vaccine and less than 0.1% of patients experience Grade 4 adverse effects to Moderna’s vaccine. Swelling, pain, rashes and redness at the injection site are common.

While some patients have experienced anaphylaxis, all have recovered.

Covid-19 vaccines have not been tested on pregnant or lactating women or on children. It also will need to be tested on millions of more people for scientists to understand how the vaccine may interact with certain chronic illnesses or other drugs.

Check out MedShadow’s vaccine side-effects tracker for more details.

How long were test patients followed and why?

The FDA required that patients in the Phase 3 trials be followed for a median of two months after the second shot before the data would be reviewed for its approval.

When it comes to side effects, the CDC considers vaccinations different from other medicines, because they aren’t taken continuously. In general, the CDC designates adverse events that happen within six weeks of administration to be potentially linked to vaccines. In the case of the Pfizer and Moderna vaccines, the mRNA is broken down within days of the injection, so it doesn’t remain in your body long term.

The CDC is tracking possible adverse reactions in early recipients through its V-safe app. The agency initially announced that it would follow these patients for six weeks but has since said it will check in on them at three months, six months and one year after receiving the vaccine. Individuals can also report adverse effects through VAERS, the government’s vaccine adverse event reporting system.

Who has been tested for the vaccine?

The vaccines have been authorized for adults. While Moderna’s and Johnson & Johnson’s vaccines have the okay for patients 18 and older, Pfizer’s original trial included a small number (163) of 16- and 17-year-olds and has been recommended for patients 16 and older. On March 31, the company announced that the vaccine was safe and effective for patients 12-15 years old.

The vaccines were effective in both men and women, regardless of weight or race. While Pfizer’s vaccine appears to be just as effective in older patients (65 and older) as in younger ones, Moderna’s vaccine offered slightly less protection (86% compared to 96%) in older patients versus younger ones.

None of the trials included pregnant or lactating women. Pfizer has started a trial in pregnant women and Johnson & Johnson says it plans to. While immuno-compromised people (such as those with the HIV, human immunodeficiency virus) were included in the trials, there isn’t enough information yet to determine if the vaccines offer different levels of protection to these groups.

A small study in pregnant and lactating women demonstrated that the Pfizer and Moderna vaccines were safe and led to a strong immune response in these patients. Additionally, the shots seemed to  confer at least some immunity to the fetuses and newborns through placenta and breast milk. The study has not been peer reviewed, and is not as large as clinical trial.

Moderna and Pfizer are both currently testing their vaccines in younger teenage patients.  Moderna announced it is starting a trial in patients as young as 6 months to 11 years old. Doctors have told the New York Times that side effects can be more intense in children than adults. The new trial will start with very low doses and increase them to find the lowest effective dose for children. The children will be followed for a full year.

Johnson and Johnson says it plans to test its vaccine in babies and children, pregnant and lactating women, and immunocompromised patients in upcoming trials.

Will the COVID-19 vaccine protect me from mutated versions of the virus?

Researchers have identified several mutated forms of the virus spreading in the UK, South Africa, Brazil, and elsewhere. Scientists believe the vaccines will still protect against these strains, but are running studies to confirm it. Moderna and Pfizer announced that their vaccine may offer slightly less protection against the variant from South Africa than it does to the variants originally tested. Johnson and Johnson also announced that their vaccine is less effective against this variant, but they believe it still prevents the most severe outcomes. Those in the study that did get the disease did not end up hospitalized.

Moderna is working on creating a “booster” shot that will offer greater protection.

“We’re doing it today to be ahead of the curve, should we need to,” Dr. Tal Zaks, Moderna’s chief medical officer, said in an interview cited in The New York Times in January. “I think of it as an insurance policy.”

“I don’t know if we need it, and I hope we don’t,” he added.

Can I Throw Away My Masks After I Get the Vaccine?

There are several reasons that you should continue to wear your mask and social distance after getting the vaccine. First, the clinical trials did not continuously test every participant for COVID-19; they only tested those patients who displayed symptoms. There is a chance that the vaccine protects people from getting sick, but not from contracting and spreading the virus without showing symptoms.No vaccine is 100% effective and it can be less effective especially in people with weakened immune systems. You’ll want to keep protecting those around you who are elderly, have cancer or other conditions that cause immunodeficiencies.

Nonetheless, the CDC announced guidelines suggesting that small groups of fully vaccinated people (people who received all doses of the vaccine more than two weeks ago) can now safely spend time together indoors without masks. These individuals should still wear masks in public spaces.

Got more questions you want MedShadow to answer? Contact us.

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18 thoughts on “COVID-19 Vaccine: Your Questions Answered

    1. The American Society of Hematology (ASH) has some good resources on this topic. Here is one specifically about ITP blood disorders and COVID-19

      Here is another about the vaccine and a transplantation and cellular therapy

      And here is a list of their resources on other topics if you’d like to explore further.

  1. Should I receive second Modena vaccine if I had an immediate allergic reaction? I have received multiple answers from dr, pharmacists and Health District. I had a tingling in head, tongue and heaviness in entire body. I was given Benedryl and tingling stopped within 7 or so minutes. Heaviness continued and I slept about 4 hours upon returning home.

  2. I received the first dose of Moderna. I had fever and chills that lasted a day or two but I was warned about those, no big deal. But my arm where I received the shot hurts so bad it feels like it’s about to fall off and it’s been almost two weeks. I’m not sure if this is something to be concerned about and if I should report this or who I should report this too. This isn’t a minor pain, it hurts like heck.

    1. Hi Cheryl,
      You can report effects like these to VAERS.
      You can also register for the V-Safe app if you haven’t already, which is specific to COVID-19 vaccines.
      We’d also recommend calling your healthcare provider who may suggest changes to look out for or treatments that might help.

  3. i heard the side effect is more severe when you receive the 2nd shot. I also heard advices like taking ibuprofen ahead of the 2nd shot may lessen the side effect. Any truth to that? any other advices?

  4. Just wanting to report for statistics.
    Dose 1
    No pain at all at injection
    2 hours post- very sore arm and fatigue
    Overnight fatigue, painful muscles and joints. Restless sleep,
    Next day – severe headache lessening joint and muscle pain
    Previous conditions
    Typ1 diabetic for 35 years cured by transplant
    Kidney pancreas transplant Dec 21, 2021.
    Anti-rejection meds and other post transplant drugs and supplements.

  5. I received my second Phizer vaccine on February 17. About a week later I started to get these very very tiny red dots on my body. They last about 4to5 days and then they turn brown. Could this be a reaction from the Covid vaccine. I went to a dermatologist and they can’t give me an answer as to what it is. I hope you can answer my question and put my mind at ease. Today isMarch 11 and I am still getting the red ducks but less. Thank you and I hope I can get an answer

  6. I know this sounds bizarre, but I had my second shot of Phizer vaccine today and I was injected well below the deltoid. Will I still be immunized effectively?

  7. My resting heart rate has changed after the first vaccine of Pfizer. Usually 65-68, now it ranges 78-109. This is the third week since first dose. I get the second in a week. I feel my heart pounding louder at night when I first lay down. I wear a Fitbit, so it’s noticeable to track resting heart rate.

  8. I had almost every possible side effect. about 8 hours after my second shot I had a terrible headache like someone hit me with a hammer. It got so bad it was like I had the drunk spins. Threw up a few times Had the chills so bad that I imagine what going thru drug withdrawls much feel like. Terrible body aches. Shortness of breath. Took my pulse / ox and my oxygen level was mid 80’s. It should be over 95. Felt the the same way all the next day. Got a fever, still had chills, dizzy and vomiting. Headache and slight fever also. Next day I got diarrhea for 2 days. Still achy, then 5 days after vaccine, I got “Covid arm” a hot red rash on the arm I h ad the shot on. Had that for a few days. Still hardly any energy. Luckily my husband took good care of me. Stayed on “the brat diet” all week. No appetite Took about 10 days to get back to about 90%. THEN, OVER 3 WEEKS PAST THE SECOND VACCINE, I had lymph nodes swell up in both my calves. Felt like I was very bruised! Went to the doctor and they said they should pass. The swollen nodes moved to both my arms, then my groin area and still there. I am a bit concerned about what this vaccine is doing to my body.

  9. PFIZER . First shot no side effects at all. Second shot, fatigue, very sore arm-could not lift it. Pain came on gradually until it woke me up in the middle of the night. Loose bowels. Stiff legs. Lasted about 24 hrs. Starting to feel like I’m coming out of it but not sure yet on third day.

  10. Received 1st dose Pfizer… nothing at all for side effects. Today received 2nd and my arm hurts soooooooo bad I’m in tears. It doesn’t hurt at injection site but bicep kills, near top side of arm/shoulder.. feels like my arm is in a vice grip!!!! OMG … God help me!

  11. The red dots may be petechiae. It may be a good idea to see a hematologist and/or PCP and get a complete blood count panel to test your platelet levels. Blessings and healing to you.

  12. I’ve had my first Pfizer vaccine. No sore arm at all, but headache and one week after vaccine chills and fatigue. Feels like a cold or allergies. Seems a long time before I had any side effects.

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