HealthTap Debunks Five Top Myths about the Pfizer and Moderna COVID-19 Vaccines; Answers the Big Questions About Safety and Efficacy

These two vaccines in particular are both safe and effective, and people have a responsibility to get vaccinated at the earliest opportunity.

Dr. Geoff Rutledge, MD, PhD
Board Certified in Internal and Emergency Medicine
Former faculty at Harvard and Stanford
Chief Medical Officer, HealthTap

Perhaps not surprisingly, there is a remarkable amount of misinformation about the two COVID-19 vaccines that are the first to be used on the broader U.S. population.

The Pfizer vaccine, for which the FDA issued Emergency Use Authorization (EUA) on December 11, 2020 has already been given to thousands of healthcare workers, as well as nursing home staff and residents. The vaccine from Moderna and the National Institute of Allergy and Infectious Diseases (NIAID) was approved on December 18, 2020. Over the past few days, HealthTap polled its 90,000 doctors, finding that 96% of doctors who have an opinion say that these vaccines are both safe and effective.

On behalf of our doctors and the entire team at HealthTap, we're encouraging our members and the public at large to get vaccinated as soon as the vaccine is available to them.

Take care to verify the information you find online for accuracy, and avoid spreading misinformation during this crucial time. If we manage this next phase of the pandemic well, we're on our way to a safer and less worrisome world relatively soon.

Myth or Fact?

Don't be fooled by misinformation!

The Pfizer and Moderna vaccines can change a person's DNA.

Both vaccines use a fragment of the virus's genetic code (messenger RNA) that does not do anything to the DNA in human cells.[1]

The Pfizer and Moderna vaccines were developed and tested using fetal tissue.

The Pfizer and Moderna vaccines are produced and tested without the use of any type of human cells.[2][3]

Once a person is vaccinated they don't have to wear a mask.

People will still need to wear masks until we reach herd immunity, which occurs when most of the population is vaccinated or has recovered from COVID-19.[4]

Both vaccines are 90 to 95% effective at preventing the transmission of COVID-19.

These vaccines are 94% to 95% effective at preventing the person who is vaccinated from developing symptoms. We still don't know if people who are vaccinated will get asymptomatic infections that can transmit the virus to others.[5]

The vaccines have dangerous side effects for many people.

There were no serious side effects in large trials for both vaccines. Since releasing the Pfizer vaccine, there have been just three reports of an immediate allergic reaction (anaphylaxis), all of which were readily treated. Just like medicines, all vaccines very rarely cause allergic reactions (for example, the flu shot has a one in 1 million chance of causing an immediate allergic reaction). Mild side effects, such as sore arm, low-grade fever, and fatigue are common and clear up without treatment in 1 to 3 days.[6]

Frequently Asked Questions

with answers provided by

Dr. Geoff Rutledge, MD, PhD
Board Certified in Internal and Emergency Medicine
Former faculty at Harvard and Stanford
Chief Medical Officer, HealthTap
What COVID-19 vaccines have been approved by the FDA?
The Pfizer/BioNTech vaccine has been granted an emergency use authorization (EUA) by the FDA for anyone over the age of 16. The Moderna vaccine has been granted an emergency use authorization (EUA) by the FDA for anyone over the age of 18. Other vaccines are in late stage clinical trials, but have not yet applied to the FDA for approval. [7]
Do the Pfizer and Moderna vaccines work in the same way as other vaccines?
Other vaccines include either a component of a virus or bacteria, or an actual live but weakened organism. The new Pfizer and Moderna COVID-19 vaccines are different, because they do not contain any component of the virus. Instead, they have a small slice of the genetic code of the virus in the form of messenger RNA (mRNA). The mRNA gives instructions for your cells to manufacture the spike protein of the virus, which enables your immune system to make antibodies against the virus. Antibodies give you immunity, so you will not get sick if you are exposed to COVID-19. [8]
Are there other vaccines coming soon?
The most promising vaccine candidates that are undergoing the final "phase III" clinical trials include the AstraZeneca/Oxford University AZA-1222 vaccine, and Johnson&Johnson Ad26.COV2.S vaccine. These vaccines put COVID-19 DNA inside a different virus (adenovirus) that carries the COVID-19 protein sequence into cells, which make messenger RNA (mRNA) from the viral DNA, which enables the cell to manufacture the COVID-19 spike protein, which triggers the production of antibodies that protect you from the virus. There is a third vacccine that also shows promise: Novavax NVX-CoV2373. This vaccine includes the actual spike protein along with an immune-boosting chemical (adjuvent) to trigger your immune response to COVID-19. None of these potential vaccines contain the actual COVID-19 virus. [9]
If there is more than one vaccine available when it's time for me, how do I decide which one to take?
The vaccines authorized so far are equally effective. The biggest problem will be the availability of the vaccines, so whichever one is available to you is the one you should take. Recommendations for children under the age of 16 and for pregnant women are still in development, although many Obstetricians are strongly recommending that pregnant and breastfeeding women also take the vaccine. [10]
How much vaccine do we have for people in the U.S.?
As of December 18, 2020, the US government has multiple contracts for vaccines, including for 100 million doses of the Pfizer vaccine, and 200 million doses of the Moderna vaccine (together, enough to give two shots to 150 million people). Delivery of the vaccine has started, and up to 20 million doses may be available in December, with another 20-25 million doses expected in January 2021. That said, there are estimated to be about 331 million people in the U.S., so additional vaccines will need to be ordered to cover the majority of the population.
Who is eligible for the vaccine?

The CDC advisory committee on immunization practices recommended on Dec 1 2020 that people get vaccinated in the following order:

  1. healthcare workers at risk of exposure to COVID-19
  2. residents of long-term care facilities
  3. people at high risk for severe COVID-19 illness due to underlying medical conditions (which may include obesity)
  4. people 65 years and older
  5. everyone else.

It is likely that by the time the highest risk groups are fully vaccinated, we will have additional safety data on the use of these vaccines in pregnant women, breastfeeding women, and children less than 16 years old. Some government leaders have recommended that teachers also be given a higher priority for vaccination. The actual distribution of the vaccines is managed at the state level, so the specific distribution plans may vary by state. [11]

How much will the vaccine cost?
The federal government has stated that the first round of vaccinations will be free for Americans, and the Affordable Care Act (ACA) requires that health insurers offer recommended vaccinations at no cost to members. This regulation does not apply to short-term insurance plans, so the actual cost of getting vaccinated could vary. President-elect Biden has promised to "guarantee the vaccine gets to every American, cost-free", but this will be subject to congressional authorization of additional spending, and may depend on whether the president's party also controls the senate. [12]
What if I am not an American citizen? Can I still get a COVID-19 vaccine?
Several government leaders are working hard to make the vaccine available to immigrant populations without requiring documentation, which would let non-citizens get vaccinated without worry about their status. However, in these early days there is no concrete plan or legislation, as there is not enough vaccine for American adults. We are optimistic that undocumented people will have access to the vaccine eventually, but it's difficult to speculate on when.
Should children get vaccinated?
Not yet. Healthy children are in the lowest risk category, so they are in the last-priority group. More important, the first clinical trials of the two approved vaccines excluded children, so we need to wait for the results of the current phase III trials that include children. [11]
Should pregnant woman get vaccinated?
Probably. The initial clinical trials did not include pregnant women, so there isn't good safety data. On the other hand, pregnant women and their babies are at significantly higher risk from COVID-19, and many doctors believe that any possible risk of the vaccine during pregnancy is greatly outweighed by the risk of not getting vaccinated. The American College of Obstetricians and Gynecologists (ACOG) issued a statement advocating for vaccinating pregnant women. Pregnant women should discuss this with their obstetrician. [10]
How do we know that there was adequate testing to ensure the vaccine is safe and that there won't be any unanticipated long-term effects?
The phase III clinical trials of the first two vaccines followed the standard and comprehensive testing and review procedures, and included more than 74,000 people. Based on prior experience with this kind of vaccine, and because the vaccines have so little other material (they are mostly just mRNA), there is an extremely low risk of significant long term effects. On the other hand, there is a substantial risk of death and other long-term effects of getting COVID-19, so any possible unexpected risk from the vaccine are miniscule in comparison. [13]
What are the risks of getting vaccinated?
The main risks of getting vaccinated are short term side effects, which may include soreness of the arm, low-grade fevers, muscle aches, and fatigue. These side effects can last 1 to 3 days, and get better without treatment. The incidence of these minor side effects appears to be greater after the second shot. Very rarely, an immediate allergic reaction may occur, so it is recommended that the vaccine be administered in a healthcare setting that can treat such reactions. People who have a history of severe allergic reactions (anaphylaxis) should be monitored more closely when they receive the vaccine. [14]
Can I get COVID-19 from the vaccine?
Absolutely not. There is no virus in the vaccine, so it cannot give you COVID-19.
If I have already had COVID-19, should I get vaccinated?
Probably. Current recommendations are that every adult should be vaccinated. People who were previously infected with COVID-19 may be in a lower priority group for receiving the new vaccine. [15]
Will the COVID-19 vaccine protect me from other viruses?
Probably not. The vaccine will protect you from any virus that has the same spike protein, but COVID-19 is the only virus that we know of that has that protein. [16]
Based on current information, when is your best guess of when we can stop wearing masks and social distancing?
We'll be able to stop wearing masks and social distancing when enough people are immune and unable to spread the virus. To reach this "herd immunity" will require a significant proportion of the population to be vaccinated. The exact proportion required to achieve herd immunity depends on how strictly people follow pandemic restrictions. In areas where people are not masking and social distancing, at least 75%, but preferably more than 85% of the population will need to be immune. [4]
What should I say to my friends or family who think the vaccine is unsafe?
Avoid arguing or implying that the person is foolish or not intelligent. Then point to facts from reliable sources. The vaccines have been thoroughly and systematically tested, and are very safe. Getting COVID-19 on the other hand is more than unsafe, it can be deadly and can lead to serious long-term consequences. Everyone should be more afraid of COVID-19 than of a well-tested vaccine that will protect them! [17]
How do I know what information to trust online?
It's important to evaluate online medical information with extra care, especially regarding COVID-19 and its treatment. Note the publisher and original source of the information to ensure both are reputable and authoritative. Websites ending with .edu or .gov are usually trustworthy. Many websites that end with .org or .com are trustworthy as well, but not all. Sometimes organizations give themselves names that sound like well-known organizations as a way of misleading readers. Find out who is paying for the information and what their purpose is. Studies are often commissioned by organizations that have a financial interest in a certain type of results. Look for verification of the information by a doctor or other medical professional. Most credible websites will cite the names and titles of doctors or researchers who have reviewed the content for accuracy. Lastly, make sure the page you're reading is current. It's easy to find outdated content online, which might not be wrong, but it's better to rely on something that includes the date to be sure you're getting the latest and best information.
HealthTap polled its doctor network, finding that 96% of doctors who have an opinion say that these vaccines are both safe and effective.

Both the Pfizer and Moderna vaccines are the first that use messenger RNA (mRNA) technology and have proved both safe and highly effective.

The vaccines were comprehensively tested with rigorous clinical trials that achieved results quickly because there were so many new cases of COVID-19 among those who did not receive the vaccine. In addition, federal funding of development and advance purchase allowed the manufacturers to conduct large trials with unprecedented speed, a historic achievement exemplifying the power of private-public collaboration for public health. These vaccines empower your cells to create one of the virus proteins, to which your immune system reacts to produce antibodies that defend against the virus and prevent you from getting sick with COVID-19. The vaccine cannot give you COVID-19, it does not contain the virus.

Dr. Hunter Handsfield
US-licensed Doctor
Infectious Diseases

This vaccine is a new type of vaccine in that it is an mRNA based vaccine. However, the basis of the vaccine itself and delivery is based on decades of solid research.

The new vaccines have been shown to be safe and very effective. There is minimal down side or side effects to getting the vaccine. And the trade off is getting COVID which has a high rate of complications.

Dr. David Mcadams
US-licensed Doctor
Family Medicine

The US FDA has the most vigorous and independent review process for vaccines in the world, so we can have confidence that these vaccines are safe and effective.

It is important to get your vaccine as soon as you can, to protect the vulnerable and our healthcare workers. We can't expect to get to herd immunity by natural means - it puts too many people at risk, strains the healthcare system, and it probably doesn't last. The vaccines are our only hope of getting enough lasting immunity in the population to be truly protective.

Dr. Donald Collins
US-licensed Doctor
Internal Medicine

COVID-19 Community Questions

Answered by HealthTap's panel of top U.S. doctors

A 59-year-old male asked:
Dr. James Ferguson answered
45 years experience Pediatrics
Some basics: Both the flu and COVID-19 can invade the lung tissue and cause a pneumonia by themselves. Pneumonia is a generic label for a serious lung infection. The vaccines mentioned can help prevent you from developing a secondary pneumonia that sometimes follows such illnesses but they do not prevent severe viral pneumonia.
A 44-year-old member asked:
Dr. Hunter Handsfield answered
52 years experience Infectious Disease
COVID-19 vaccine: As far as known, there is only one type of coronavirus (named SARS-CoV-2) that causes COVID-19. Unlike influenza, different strains are not expected to evolve year to year. How long immunization will last (e.g. need for a booster dose) won't be known until vaccines come to clinical trials to see how well they work -- several months from now. (3/10/20)
A member asked:
Dr. Geoffrey Rutledge answered
40 years experience Internal Medicine
Yes: The first vaccine for COVID-19 illness caused by the coronavirus (SARS-Cov-2) was approved by the US FDA on Dec 11 2020. The Pfizer/BioNTech vaccine is 95% effective, and has no significant serious side effects (fever and muscle soreness were common side effects). Complete protection requires two shots, 3 or 4 weeks apart. A second vaccine from Moderna also is effective and will likely be approved
A 69-year-old male asked:
Dr. Claudine nandi Lee answered
Specializes in General Practice
If available: Yes worth getting the influenza injection especially if immuno-compromised.
A 49-year-old male asked:
Dr. Richard Roberts answered
45 years experience Pediatrics
No: The vaccines prevent bacterial pneumonia. They have no effect on viral pneumonia.
A member asked:
Dr. Deborah Ungerleider answered
35 years experience Pediatrics
Unknown: No one knows yet. It is too early to tell whether a vaccine, once developed, will be a one-time vaccine, or need a booster after a certain number of years, or if it will be annually (like the flu vaccine). As more research is done, that , and experience once the vaccine is widely available, will let us know.
A member asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
Too early to know: Vaccines will need to be developed, tested and evaluated over-time to answer that question.
A member asked:
Dr. James Ferguson answered
45 years experience Pediatrics
Maybe/not: Anyone who gets flu or covid-19 can develop a dangerous pneumonia during the illness. Having the immunity provided by the vaccine against strains of a common cause of pneumonia is helpful for anyone. However, there are other causes of pneumonia & covid-19 also triggers lung failure from acute respiratory distress syndrome (ARDS) which is a different issue. If it fails you die.
A member asked:
Dr. Lauren Bickel answered
Specializes in Family Medicine
Maybe not: Agree that pneumonia vaccine protects against the most common types of pneumonia, which can occur in people with COVID 19. But it appears that COVID 19 virus itself causes a bilateral viral pneumonia which can be very serious & even fatal in people with underlying lung conditions & other medical problems
A member asked:
Dr. James Ferguson answered
45 years experience Pediatrics
Yes: The American Academy of Pediatrics has issued a position statement advising all parents to have their kids under 2 get their routine vaccinations on time. Some vaccine preventable diseases like whooping cough are most deadly in the under 1 yr age group.
A member asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
Yes: There are a number of providers who have infant/ child immunizations done by appointment now - one patient at a time. They allow for time between patients to clean the area. So, yes immunizations are still recommended.
A 62-year-old female asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
Vaccine studies: Although there is on-going research - unfortunately even when rushed, it takes quite a while to get a vaccine developed, approved and made. There is some promising research coming out of the U.K. There need to be a number of steps before a vaccine can be marketed - these are safeguards.
A 62-year-old female asked:
Dr. Geoffrey Rutledge answered
40 years experience Internal Medicine
This vaccine is safe: The COVID-19 vaccine development has been much faster compared to previous vaccines, enabled by new technology. But the testing/evaluation of effectiveness and safety has been done according to the usual very strict standards. Trials of COVID-19 vaccines have included more than 75,000 participants, so if if there were serious side effects we would know. These vaccines are safe and effective
A 32-year-old female asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
COVID 19: In pregnant women who develop COVID-19 pneumonia, early data show approximately the same rate of intensive care unit (ICU) admissions as in the nonpregnant population but an increased risk of preterm and cesarean delivery. REF: https://www.uptodate.com/contents/coronavirus-disease-2019-covid-19-pregnancy-issues. Would discuss with your doctor and partner. Take care.
A 54-year-old male asked:
Dr. James Ferguson answered
45 years experience Pediatrics
Wouldn't count on it: Any such information wherever you found it is little more than speculation at this point. The viruses involved are quite different & antibodies triggered by a vaccine are selective to the type of stimulus it responds to (here MMR). Much like puzzle pieces if it is not the same puzzle, a piece may come close but not actually fit.
A 60-year-old male asked:
Dr. James Ferguson answered
45 years experience Pediatrics
Hard to speculate: I suppose when the regional covid-19 activity wanes to a sporadic level & hospitalizations drop off there would be less fear in the population. When or if that will occur is hard to predict. The emergence of improved early identification & treatments along with a drop in case fatality rate will also help. Feeling safe is a personal issue that varies with the individual. At some point we will adapt
A 60-year-old male asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
COVID 19: I agree with Dr. Ferguson. There are many different vaccines in testing phases in various countries. The issue is not just having a vaccine but is also having sufficient amounts to allow for large scale vaccinations.
A 38-year-old female asked:
Dr. Manuel Lowenhaupt answered
39 years experience Infectious Disease
COVID vaccines: The two leading vaccine candidates are synthetic mRNA vaccines. Messenger RNA (mRNA) is the template for a cell to build a protein. These vaccines instruct the body's cells to build the "spike" protein only from the COVID-19 virus. The spike alone is not able to replicate or attack the body but can trigger a robust immune response that will stop infection of the wild virus.
A 38-year-old female asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
COVID 19 vaccine: Traditional vaccines may use inactivated virus organisms to produce antibodies. But the new Pfizer/ BioNTech vaccine uses messenger RNA that causes our cells to produce Spike proteins which we then develop an immune response to.
A 38-year-old female asked:
Dr. Gurmukh Singh answered
48 years experience Pathology
1-2 weeks: Depending on the type of vaccine, it will take 1-2 weeks after the second dose for immunity to kick in. If and when a single dose vaccine becomes available, it will be 1-2 weeks after the vaccination. For now, wear a mask, practice social distancing and wash your hands often. Wish you good health!
A 38-year-old female asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
COVID 19 vaccines: I checked multiple sites and could not find a direct answer to your question. Both mRNA vaccines would require 2 doses. Pfizer’s booster shot will be given three weeks after the first one; Moderna’s is spaced four weeks later. REF: https://www.washingtonpost.com/health/2020/11/17/covid-vaccines-what-you-need-to-know/?arc404=true
A 56-year-old male asked:
Dr. Geoffrey Rutledge answered
40 years experience Internal Medicine
Not from the vaccine: The COVID-19 vaccine does not have virus in it, and cannot make you a carrier. After vaccination, you won't get sick from COVID-19, and it is not likely that you would be able to spread the virus if you were exposed to it — but we do not yet know that with certainty. There remains the possibility that vaccinated individuals could unknowingly spread the virus for a period of time after exposure.
A 25-year-old female asked:
Dr. Hunter Handsfield answered
52 years experience Infectious Disease
COVID vaccination: The data available so far indicate the three vaccines to be available soonest are very safe. Serious side effects have been rare; the vaccines are far less dangerous than COVID-19 itself and everybody should be vaccinated. If enough people in any country are vaccinated, over time the virus and illness will be reduced to low numbers. It's not yet known if it can be eliminated entirely.
A 42-year-old male asked:
Dr. Karna Gendo answered
25 years experience Allergy and Immunology
No impact so far: So far, no effects on fertility have been found. The spike protein on the Covid-19 virus and a protein that makes up the placenta have only a small amount in common, almost certainly not enough for the immune system to attack the placenta. https://fullfact.org/health/vaccine-covid-fertility/
A 42-year-old male asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
COVID 19 vaccine: I am not aware of COVID 19 vaccinations causing infertility. You can learn more about this at: https://www.nejm.org/doi/full/10.1056/NEJMoa2034577
A 36-year-old female asked:
Dr. James Ferguson answered
45 years experience Pediatrics
To be decided later: Initial efforts are likely to focus on front line hospital workers/all first responders followed by nursing home residents & then all those over 60 with medical conditions. Those with other medical conditions under 60 would eventually be in line for the initial available stock of vaccine. Moderna and other vaccines will likely be readily available to all by next summer (many will refuse it)
A 41-year-old member asked:
Dr. Heidi Fowler answered
24 years experience Psychiatry
COVID 19 vaccine: In general, if one has a weak immune system it would probably be safer to take the vaccine & to be protected. Any contraindications (reasons you should not be vaccinated) will be published by the drug companies.
A 41-year-old member asked:
Dr. Christine Hom answered
29 years experience Pediatrics
Vaccine: The vaccine cannot cause COVID, it only codes for a surface protein (spike). There is a lot of concern for people taking immune suppressing drugs or primary immune diseases. Some considerations are the risk of acquiring COVID disease versus the risk of the vaccine. Right now, the experience with this vaccine is being accrued, including safety and efficacy for people with immune conditions.

More questions about COVID-19 vaccines? Talk to a doctor now.

HealthTap is here to give you personalized guidance and answer your questions about COVID-19. Talk to a doctor over video or by text, post your own question to doctors, or assess your symptoms with our AI.

References

[2] Vaccines and Related Biological Products Advisory Committee Meeting, December 17, 2020, https://www.fda.gov/media/144434/download
[4] The false promise of herd immunity for COVID-19, https://www.nature.com/articles/d41586-020-02948-4
[7] COVID-19 Vaccine EUA Recipient/Caregiver Fact Sheets, https://www.cdc.gov/vaccines/covid-19/eua/index.html
[8] COVID-19 vaccine: A recent update in pipeline vaccines, their design and development strategies, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7685956/
[11] The Advisory Committee on Immunization Practices’ Interim Recommendation for Allocating Initial Supplies of COVID-19 Vaccine — United States, 2020, https://www.cdc.gov/mmwr/volumes/69/wr/mm6949e1.htm
[12] Frequently Asked Questions about COVID-19 Vaccination, https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq.html
[13] How Can We Be Sure the New COVID-19 Vaccines Are Safe?, https://www.ucsf.edu/magazine/covid-vaccine-safety
[14] What to Expect after Getting a COVID-19 Vaccine, https://www.cdc.gov/coronavirus/2019-ncov/vaccines/expect/after.html
[17] How to Handle Misinformation in the Age of Dr. Google, https://www.aafp.org/fpm/2020/0900/p48.html