DISCLAIMER: The advice in this article is intended for informational purposes only. It is not meant to replace or substitute advice, diagnosis or treatments given by a medical professional. Please consult your doctor with questions you may have regarding a personal medical condition or treatment.
Check out these up-to-date insights and answers to your COVID-19 vaccine questions from our Chief Medical Officer and senior medical experts.
Is this vaccine safe? How many people were in the trials? Was that enough to assume safety?
The Food and Drug Administration (FDA) sets forth rigorous standards that must be met before they will consider granting emergency use authorization (EUA) for a vaccine, which it granted to the Pfizer vaccine on 12/11/2020. For safety, the data must include a minimum follow up period of at least two months after the participant received the second dose of the vaccine to monitor for any late adverse effects. In addition to the FDA reviewing the data, the Centers for Disease Control and Prevention (CDC) does as well, along with an independent panel of non-government physicians and other vaccine experts not involved in the studies. Based on their review of the scientific data, these groups found that the vaccines are safe. Safety data will continue to be gathered as more and more vaccinations are given.
In terms of numbers of participants in these large trials, the Pfizer SARS-CoV-2 vaccine trials had 43,448 participants, and the Moderna SARS-CoV-2 vaccine trial had more than 30,000 participants.
What were the main side effects people experienced? Anything serious?
The main symptoms reported after the COVID-19 vaccine are as follows:
Pain at injection site
Injection site swelling
Injection site redness
Of those that developed symptoms after the vaccination, most report the second injection causes more significant symptoms than the first.
The most serious side effect attributed to the vaccination, thus far, has been several instances of severe allergic reaction developing just minutes after injection. These people were swiftly treated and are all okay. It should be noted that several of these people had a previous history of severe allergies and routinely carried epinephrine with them in case of an allergic reaction.
How can we best distinguish expected vaccine side effects from symptoms of acute illness with COVID?
If patients have symptoms of injection site pain/tenderness, fatigue, fever, muscle/body aches, etc. within hours to a couple days after receiving the injection, then these are very likely related to the vaccine and not COVID-19. If there are other more specific symptoms like rhinorrhea/congestion, cough, chest pain, loss of taste/smell, vomiting/diarrhea, etc. then it could be COVID-19, or some other virus, but are likely not from the vaccine.
Will the vaccine protect me from the new variants?
At this time, the current vaccine will still protect most of us from the new coronavirus variants. But there is one variant, found in South Africa, and now in small numbers in several other countries, that researchers are closely studying that may infect people who already had COVID in the past. Studies are underway to find out if the current vaccine can protect against this variant. This is another reason why continuing to wear masks, social distance and wash hands often are very important to prevent the spread of COVID, including any new variants.
Should I worry about how fast these vaccines were developed?
No, there should be no safety concerns related to how quickly the vaccine was produced.
There are several contributing factors that led to the quick turnaround of the vaccines. First, the technology used to make the vaccines has been studied and in development for more than a decade. Second, making a vaccine with the mRNA technology (the Pfizer and Moderna products) is also much simpler and faster than the alternative technologies, such as those used to make the flu vaccine, so there is a shorter manufacturing time. The US government helped fund the trials and development of the vaccines, so that helped speed up the process as well. Lastly, getting enough subjects for the trials was quick and relatively easy as the illness is so pervasive, and people had a real interest and felt a responsibility to enroll.
These studies were shorter than normal because of the urgent need for the vaccine during the pandemic. Are there any long-term effects that we need to be watching out for in the upcoming year?
There are no indications, thus far, of any long-term effects to watch out for. That said, ongoing safety data collection will continue through both voluntary self reporting of symptoms that develop after vaccination (done through an app on your smartphone or computer), and formal reporting by vaccine providers.
My parents are elderly and are not sure they should get the vaccine. Does it work in older adults? Did they study it in older adults?
Yes, both Pfizer and Moderna did study their vaccines among older people, a group who often have weaker responses to vaccines. Efficacy was still very good at 94% for the Pfizer vaccine in those 55 and over and 86% for the Moderna vaccine in those 65 and older. For comparison, efficacy for the younger population is 95% for these vaccines. So, these two vaccines are still very useful for preventing COVID-19 in older people.
Should I be concerned about the use of new technology (mRNA) to make these vaccines?
No, you should not be concerned about the technology used to make the vaccines. Like all vaccines, COVID-19 mRNA vaccines have been rigorously tested for safety before being authorized for use in the United States. Additionally, it is important to know that the mRNA technology was not newly developed for the novel coronavirus, it has actually been studied and in development for more than a decade. So, researchers and vaccine developers already had experience with it.
mRNA vaccines do not contain a live virus so do not carry a risk of causing COVID-19 in anyone. Also, mRNA from the vaccine never enters the nucleus of the cell and does not affect or interact with a person’s own DNA. Lastly, after our body uses the information in the mRNA it is then broken down by our cells, and then the immune system takes it from there to continue to make the protective antibodies.
Should people with certain autoimmune diseases or other conditions avoid the vaccines?
Having an autoimmune condition is not a reason to avoid the vaccine. The vaccine is approved for people with autoimmune diseases and weakened immune systems from health conditions or a medication. To understand the risks and benefits, people with these conditions should consult with their care provider before getting the vaccine.
I’m pregnant/breastfeeding. I know they didn’t study the vaccines in pregnant women so should I get it?
It is true that pregnant and breastfeeding women were not included in the study.. But the way an mRNA vaccine works makes it unlikely that it could have a harmful effect on pregnancy or a breastfed baby. In fact, the Center for Disease Control (CDC) and the American College of Obstetricians and Gynecologists (ACOG) both state that pregnancy and breastfeeding are not reasons to avoid the vaccine. If a pregnant or breastfeeding person is part of a group that is recommended to receive a COVID-19 vaccine (e.g., healthcare personnel), they may be offered the vaccine. But to understand the risks and benefits, they should consult with their care provider before getting it.
They didn’t study the vaccine in kids. Does that mean they can’t get the vaccine? Would it be unsafe?
Yes, neither vaccine is approved for use in children. The Pfizer vaccine is not approved for use in children under the age of 16, and the Moderna vaccine is not approved for children under 18. We do not have any safety information on how the vaccine works in children as they were not included in the study. We will learn more about this information after further studies are done that include children.
I got sick/sore/swollen, etc after the first one. Should I really get another dose?
Yes, to be fully protected you need to get both shots of the vaccine. The vaccine does not take full effect and cannot protect you from COVID-19 until about one to two weeks after the second shot.
I’m trying to get pregnant. Should I wait to get the vaccine?
It is true that pregnant and breastfeeding women were not included in the study. But the way an mRNA vaccine works makes it unlikely that it would have a harmful effect on pregnancy or a breastfed baby. In fact, the Center for Disease Control (CDC) and the American College of Obstetricians and Gynecologists (ACOG) both state that pregnancy and breastfeeding are not reasons to avoid the vaccine. If a pregnant or breastfeeding person is part of a group that is recommended to receive a COVID-19 vaccine (e.g., healthcare personnel), they may be offered the vaccine. But to understand the risks and benefits, they should consult with their care provider before getting it.
How effective are the vaccines in preventing severe COVID-19 disease?
Both the Pfizer and the Moderna studies showed that the mRNA COVID-19 vaccines are very good at preventing severe cases of COVID-19. Both the Pfizer and Moderna vaccine results are very strong, with very few people in the study getting severe cases of COVID-19.
How effective are they in preventing asymptomatic shedding? Will people still have to wear masks after getting vaccinated?
While we do know that both mRNA vaccines are very good at preventing someone from getting symptoms from the virus, we don’t yet know if they can prevent asymptomatic viral shedding. So, we still need everyone to wear masks after getting the vaccine until this information is available.
What is the efficacy after a single dose? After two? How long will you have to space out the two doses?
The efficacy after the first dose of the Pfizer CoVID-19 vaccine is about 52%. After two doses of the Pfizer vaccine the efficacy reaches 95%. The Moderna vaccine trial did not have a formal single-dose arm of the study to make an adequate comparison so we cannot comment on efficacy after the first dose, but after the second dose efficacy was 94.5%. For the Pfizer vaccine, you need to wait 21 days between doses. For the Moderna vaccine, it is 28 days between doses.
How long is the vaccine good for?
We do not yet know for how long the vaccine will provide protection against COVID-19. In time, scientists will learn if people need a booster shot in two to three years after their second COVID-19 shot.
Which vaccine is better? Which vaccine should I get?
Both the Pfizer and Moderna mRNA vaccines had a success rate of well over 90%. So, both are equally effective at preventing the illness from COVID-19.
Herd Immunity Questions
What percent of the population will need to get vaccinated to get “back to normal”?
Public health officials estimate that 70 to 75 percent of people need to be vaccinated before we can get back to “normal life” and move freely through society without masks and social distancing.
Should I get the vaccine if I already had COVID-19?
Yes, even if you had COVID-19, you should still get the vaccine because it is not clear how long the immunity lasts after having had COVID-19.
Should I get an antibody test before getting the vaccine?
Antibody testing is not currently recommended to assess for immunity after vaccination or the need for vaccination.
Why are these other people being prioritized before me?
There are not enough vaccines for everyone to get it right away. While more vaccine doses are being made, people most at risk of getting COVID-19 will get it first. This includes healthcare staff and patients in long-term care facilities.
DISCLAIMER: The advice in this article is intended for informational purposes only. It is not meant to replace or substitute for advice, diagnosis or treatment from a medical professional. Please consult your doctor with questions you may have regarding a personal medical condition or treatment.
Meet Our Doctors
Dr. Todd Thames is a Senior Medical Director with a demonstrated history of working in hospitals & the healthcare industry. Skilled in Healthcare Management, Healthcare, Medical Education, Medicine, and Working with Physicians. Strong healthcare services professional with a Master of Healthcare Administration focused in Healthcare Administration from Trinity University.
Dr. Todd Thames, MD, MHA, FAAFP
Dr. Tista Ghosh is a CDC-trained epidemiologist and physician leader, the former Chief Medical Officer of the state of Colorado, and a former appointee to the U.S. Community Preventive Services Task Force. She currently serves as epidemiology lead and Senior Medical Director for Grand Rounds.
Dr. Tista Ghosh, MD, MPH
Dr. Heather Hockenberry is a family practice and urgent care medicine physician with over a decade of clinical experience in direct patient care prior to coming to Grand Rounds. Her role at Grand Rounds is as a leader and mentor to the large medical team supporting them with her clinical knowledge and expertise to ensure quality care for our patients.