Frequently Asked Questions - COVID-19 Vaccine Safety and Effectiveness

Vaccine Safety

Vaccine Effectiveness

How did the vaccines get approved so quickly?

Production of the COVID-19 vaccines began sooner than is typical. Normally, production starts after a pharmaceutical company completes the development stage for a vaccine, which includes rigorous testing for safety and effectiveness. Every vaccine goes through a series of reviews and approvals by the FDA and the Advisory Committee on Immunization Practices (ACIP), among others. In the case of COVID-19 vaccines, the federal government invested taxpayer dollars to encourage pharmaceutical companies to start production before the development stage completed.

The vaccines are still going through the same rigorous testing, review and approval process to establish safety and effectiveness.

Can I stop wearing a mask and social distancing after I’ve been vaccinated?

People who are fully vaccinated (meaning it has been two weeks since your second dose of Moderna or Pfizer vaccine, or two weeks since your single dose of Johnson & Johnson vaccine) do not need to wear a mask or physically distance, except where it is required by laws, rules, and regulations. You should wear a mask and social distance on public transportation and if requested by workplaces, stores, schools, places of worship, for example. Fully vaccinated or not, it is advised to wear a mask in crowded places.

We will also continue to require all Henry Ford visitors to wear a face mask, as we have many patients with comorbidities who are vulnerable and may not be vaccinated yet. Visit the CDC website for details about how to protect yourself and others when you’ve been fully vaccinated.

Is one type of vaccine better than the other?

Be assured that all of the approved vaccines - Pfizer, Moderna and Johnson & Johnson - are safe and highly effective. All of the vaccines help prevent infection and serious illness from COVID-19. All may produce some side effects, like arm soreness, fatigue or headache, but are usually mild to moderate and last about 24 to 48 hours.

I heard that the vaccines were made with tissue from aborted fetuses and as a person of Catholic faith, I should not take them. Is this true?

There are no fetal cells or tissues in any of the COVID-19 vaccines. Concern comes from the use of fetal cell lines in development of the vaccines. The lines involved in the COVID-19 vaccines started with two aborted fetuses from 1973 and 1985. Since then, these cells have been multiplied millions of times, which is where we get the term “fetal cell lines.”

In December 2020, the Vatican Congregation for the Doctrine of the Faith stated: “…it is morally acceptable to receive COVID-19 vaccines that have used cell lines from aborted fetuses in their research and production process.”

Pfizer and Moderna used fetal cell lines to test that the vaccines worked in the laboratory.

Johnson & Johnson confirmed that it used the 1985 cell line in the production process of their single-dose COVID-19 vaccine. The scientists used the fetal cell lines to grow the adenovirus needed to make this vaccine, but by the time the vaccine goes into the vial, the cells from the fetal cell lines have been filtered out.

The Vatican also stated: "The moral duty to avoid such passive material cooperation is not obligatory if there is a grave danger, such as the otherwise uncontainable spread of a serious pathological agent.” The Catholic Health Association echoes this position, including specifically supporting the use of the Johnson & Johnson vaccine.

Are the COVID-19 vaccines FDA approved?

The Pfizer vaccine (Comirnaty) received full FDA approval for ages 16 years and older. Pfizer is also available for people ages 5 to 15 with Emergency Use Authorization (EUA).

The Moderna vaccine (Spikevax) received full FDA approval for ages 18 years and older.

Johnson & Johnson expects to apply for full FDA approval for its COVID-19 vaccine this year.

What does FDA approval mean?

An FDA-approved vaccine has undergone the FDA’s standard process for reviewing the quality, safety and effectiveness of medical products. With FDA approval, you can be very confident that the vaccine meets the FDA’s high standards for safety, effectiveness, and manufacturing quality.

Before granting approval, the FDA carefully reviews very specific data and information about the vaccine.This includes preclinical and clinical data and information, manufacturing details, vaccine testing results, and inspections of the sites where the vaccine is made. The FDA conducts their own analyses of the information to make sure the vaccine is safe and effective and meets their standards for approval.

Full approval of the vaccines may reassure some people who have been hesitant about getting vaccinated.

Will the vaccines continue to be tested, even after they receive FDA approval?

The FDA and Centers for Disease Control and Prevention (CDC) have monitoring systems in place to ensure any safety concerns continue to be identified and evaluated in a timely manner. Pfizer and Moderna will continue to conduct studies and collect data on the safety and effectiveness of their vaccines.

Can I travel within the U.S. after I’m fully vaccinated?

Yes. Fully vaccinated travelers are less likely to get and spread COVID-19. People who are fully vaccinated (meaning it has been two weeks since their last dose of vaccine) can travel safely within the United States. Fully vaccinated travelers do not need to get tested before or after travel unless their destination requires it. Fully vaccinated travelers do not need to self-quarantine.

Fully vaccinated travelers should follow the CDC’s recommendations for traveling safely including: wearing a mask over your nose and mouth, staying 6 feet from others and avoiding crowds, and washing your hands often or using hand sanitizer.

If you are not fully vaccinated, you should delay travel until you are fully vaccinated.

Can I travel internationally after I’m fully vaccinated?

Yes, but international travel comes with additional risks. Even fully vaccinated travelers are at increased risk for getting and spreading COVID-19 and new variants. You should wear a mask, social distance when possible and wash hands or use hand sanitizer frequently.

The United States does not require you to get tested before you leave, but many countries require negative COVID-19 test results for entry. Many also require you to take another test after you’ve been in their country for a few days. If you are planning to travel to a foreign country, be sure to check that nation’s requirements.

You will need a negative COVID-19 test no more than one day before your flight back to the U.S., even if you are vaccinated. If you test positive, you will not be able to return to the U.S. until you have recovered from COVID-19. An exception is if you have recently recovered from COVID-19. You can provide your positive COVID-19 test result taken no more than 90 days before the flight’s departure from a foreign country and a letter from a licensed healthcare provider or a public health official stating that you were cleared to travel. Learn more.

Can we be sure the vaccines are safe? Will one be safe for me?

We understand that there may be concern over the safety and effectiveness of a COVID-19 vaccine. We have closely examined the FDA’s process for overseeing the many different vaccine trials. The FDA is required to make decisions that are guided by science and data regarding authorization or approval of COVID-19 vaccines. We have confidence in the FDA’s approval process and are committed to safety, quality and high reliability.

You cannot develop COVID-19 from any of the vaccines available.

Do the vaccines cause severe allergic reactions?

Though allergic reactions to the COVID-19 vaccines are rare, any vaccine or medication has the potential to cause a severe allergic reaction.

The FDA currently recommends that you avoid getting vaccinated if you have had prior severe allergic reactions to other vaccines. If you have had a previous allergic reaction to the ingredients of a particular vaccine, you should avoid getting that vaccine. Review these facts sheets about the vaccines for complete ingredient lists:  

If you have had a severe allergic reaction to medication or therapies given as injections into muscle or a vein, you may be at an increased risk of having a severe allergic reaction to the vaccines. You can get vaccinated, but you need to stay in the location where you receive the vaccine for 30 minutes after vaccination for observation and for medical treatment, if a reaction occurs.

The Advisory Committee of Immunization Practices believes it is safe to receive the vaccine if you have severe reactions to food, pets, environmental allergies or medications taken by mouth.

Can I get a vaccine if I’ve had convalescent plasma or monoclonal antibody treatment for COVID-19?

You can be vaccinated any time after receiving convalescent plasma or monoclonal antibody treatment for COVID-19.   

If my child has had MIS-C or I have had MIS-A due to COVID-19, is it safe to get the vaccine?

If someone has had a diagnosis of MIS-C or MIS-A (Multisystem Inflammatory Syndrome in Children or in Adults), it is recommended to wait 90 days from the end of the treatment to receive the COVID-19 vaccine. Please note: vaccines are currently approved for children 12 and older.

If I have an underlying health condition, can I get a vaccine?

There is currently no data that suggests having an underlying health condition is a reason to avoid getting vaccinated.     

In fact, those with an underlying illness or health condition are at an increased risk of developing severe side effects or hospitalization due to COVID-19.

If you have any condition that weakens your immune system, you may not have as much protection against COVID-19 infection. However, it is safe to receive the vaccine if you are immunocompromised. For instance, if you are infected with HIV, you're on immunosuppressive medication, or you're a transplant recipient, there are no safety concerns but you may not get as strong a protective response. That’s why it’s recommended that those who are immunocompromised follow a different schedule for COVID-19 vaccination. Please see these FAQs about the vaccines for immunocompromised people.

If you have concerns about your health and getting vaccinated for COVID-19, please talk to your primary medical provider.

Can I get a COVID-19 vaccine and another vaccine, like the flu shot, at the same time?

Yes. COVID-19 vaccines can be given at the same time as other vaccines. The American Academy of Pediatrics also supports giving childhood vaccines together with coronavirus vaccines. Youth and adults who are behind on vaccinations do not need to delay regular vaccinations in order to be vaccinated for COVID-19.

Is the Johnson & Johnson vaccine safe for women?

The CDC and the Advisory Committee on Immunization Practices (ACIP) approve vaccination with the Johnson & Johnson COVID-19 vaccine among people 18 years and older. However, women younger than 50 years old should be aware of the rare but increased risk of thrombosis with thrombocytopenia syndrome (TTS).

TTS is a serious condition that involves blood clots with low platelets. The Pfizer and Moderna vaccines are not associated with this risk. You may feel more comfortable choosing one of these vaccines if you are a woman under 50.

How do we know the mRNA vaccines don’t have any long-term effects?

While the vaccines may be new, the mRNA technology used to create them has been used for decades in treatments for cancer, influenza, ZIKA and rabies. This experience has informed us that unknown, delayed side effects show up within two months of receiving the vaccine. These vaccines have been in use for many months, since the first vaccine trials were conducted over a year ago. There are no long-term side effects to worry about.

If I’ve had a dermal filler, can I still get the vaccine?

Yes. Just know that a rare and temporary side effect is temporary swelling at the site of the dermal injection. You may want to space dermal fillers two weeks before your first vaccine dose, or two weeks after your last vaccine dose. If you experience swelling, contact your provider.

Do mRNA vaccines cause heart inflammation?

The Centers for Disease Control and Prevention (CDC) is monitoring cases of heart inflammation (also called myocarditis and pericarditis) that have been reported in young adults not long after mRNA COVID-19 vaccination with Pfizer or Moderna. The side effect is rare. Vaccination is still recommended for everyone who is eligible. Heart inflammation is much more common in people who get COVID-19, and the risks to the heart from COVID-19 infection are more severe.

Heart inflammation is typically detected within a few days of receiving the vaccination. Most patients who received care responded well to treatment and rest and quickly felt better. The CDC and its partners are actively monitoring reports of heart inflammation and reviewing data and medical records to learn more and understand any relationship to COVID-19 vaccination. More information from the CDC is available here. If you have concerns, please talk with your doctor or your child’s doctor. 

Do the vaccines have any side effects?

The COVID-19 vaccines can cause side effects that are similar to symptoms associated with other vaccines, such as injection site pain in the arm, fever, muscle pain, chills and headache. The frequency of these side effects may be greater than with other vaccines. While the symptoms may be uncomfortable, and at times intense, they should go away within 24-48 hours. Most people are able to perform their normal daily activities.

Common side effects include sore arm, headache, fatigue, lymph node swelling, nausea and/or fever, which may be worsen after the second dose of the Pfizer or Moderna vaccine. This is an indication that the vaccine is working. (That said, if you don’t experience side effects, you should not be concerned. The same level of protection is expected.)

Acetaminophen (Tylenol) may be taken after vaccination to help with any symptoms you have. (It is not recommended that you take it before getting the shot because it can lessen the effects of the vaccine.) If symptoms persist, please consult your primary care provider.

If I have side effects after receiving a vaccine, am I contagious to those around me?

If you have side effects after vaccination, this does not mean you are in any way contagious to your family or community. You cannot develop COVID-19 from these vaccines.

Are side effects from the second dose of the Pfizer or Moderna vaccine worse than the first?

Yes, in the two-dose Pfizer and Moderna vaccines, side effects tend to be more significant after the second dose. However, only 2% percent of people feel ill enough to limit their usual activities. Symptoms usually last 24-48 hours.

Acetaminophen (rather than NSAIDs) is recommended to help ease symptoms after vaccination. Do not take acetaminophen before vaccination to prevent side effects – it may lessen the effects of the vaccine.

Can a COVID-19 vaccine cause a false positive on a mammogram?

Yes, when the body is building an immune response to the vaccine, in a very small percentage of people, it can cause the lymph nodes to swell temporarily. If the lymph nodes under the arm are swollen, it could cause a false positive on a mammogram. Because of this, it is recommended that you schedule a routine mammogram either before receiving a COVID-19 vaccine, or four weeks after receiving a second dose. If you are already scheduled for a mammogram or are concerned about delaying one, contact your doctor or the breast imaging clinic.

After I’ve been fully vaccinated, how long does protection against COVID-19 last?

Studies from the Centers for Disease Control and Prevention (CDC) suggest that protection from the COVID-19 vaccines decreases over time. This is why it is important to get a booster five months after the second Pfizer or Moderna dose and two months after a single dose of Johnson & Johnson vaccine.

What are the safety guidelines I should follow after I’ve been vaccinated?

Visit the CDC website for safety guidelines for fully vaccinated people.

Even if you are fully vaccinated:

  • You should follow mask and social distancing rules and requests as required by your workplace, local businesses and places of worship.
  • You still need to wear a mask on planes, buses, trains, and other forms of public transportation, and in transportation hubs such as airports and stations.  
  • You should still watch out for symptoms of COVID-19, especially if you’ve been around someone who is sick. If you have symptoms of COVID-19, you should get tested and stay away from others.

If you have a condition or are taking medication that weakens the immune system, you should talk to your doctor to discuss what you can do. You may need to keep taking all social distancing and mask-wearing precautions to prevent COVID-19.

We are still learning how effective the COVID-19 vaccines are against the COVID-19 variants, along with how well the vaccines protect people with weakened immune systems, and how long protection against the COVID-19 vaccines lasts. These guidelines will continue to change over the coming months as we learn more.

Are the COVID-19 vaccines effective against the new variants?

At this time, the vaccines appear to be protective against the variants of COVID-19. However, they may be less effective against the variants compared to the original strain of the virus.

Researchers are working to determine just how protective the vaccines are against the new strains. They are also studying new vaccines that may protect against these variants.

What if I get COVID-19 between my first and second vaccination shots?

This unique situation means you may need to postpone your second shot. But don’t worry – it’s okay to space it out a little longer. Currently a second dose of Pfizer is recommended 21 days later, and a second dose of Moderna is recommended 28 days later. There is no need to repeat the first shot. Below are a few scenarios and guidelines for timing the second shot:

If you have COVID-19 with symptoms:

  • Wait until 10 days have passed since your symptoms started, AND
  • Wait until you haven’t had a fever for at least 24 hours and your other symptoms have improved.
  • If you have severe symptoms, wait until you are feeling better and talk to your doctor about timing for the second shot.

If you have COVID-19 without symptoms (you had a positive COVID-19 test, but you don’t feel sick):

  • You can stop isolation 10 days after your first positive COVID-19 test, and schedule an appointment after this 10-day isolation period is over.

If you’ve been exposed to COVID-19 (you had close contact with someone who got COVID-19):

  • Quarantine for 14 days and monitor your symptoms.
  • If you have a negative COVID-19 test, you can end quarantine and get your second shot if the test was five days after you were exposed.

If you have questions about getting your second shot after getting COVID-19 or being exposed, please call your doctor, who can advise you based on your personal health and situation.  

Will methotrexate diminish vaccine effectiveness?

Methotrexate is a drug given to people who have immune system disorders such as rheumatoid arthritis, psoriasis and multiple sclerosis. People who have already been taking methotrexate and then receive a COVID-19 vaccine may have a diminished immune response to the vaccine.

A recent study published in the Annals of the Rheumatic Diseases showed that one-quarter of people who take methotrexate mounted a weaker immune response to a COVID-19 vaccine. People who take methotrexate or other medications that affect the immune system can receive the COVID-19 vaccines.

If you received the COVID-19 vaccine in the past and then start taking methotrexate later, methotrexate can affect your level of protection over time. This is true for methotrexate and other medications that modify or suppress the immune system.

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