COVID-19 FAQs: Vaccines

UPDATED: 1/3/22

News, scientific understanding and guidelines about COVID-19 are continually evolving. As such, please note that some information on this page may have changed since its original publication date.

Question: Will I need a booster or a third vaccine dose if I have arthritis?

A: The terms “booster” and “third dose” are often used interchangeably when talking about COVID-19 vaccination, but there are distinct differences between the two. A vaccine dose is administered as a part of the primary vaccine series (one dose for J&J, two doses for mRNA vaccines); a booster shot is given when immunity to the primary series has likely waned over time.

*It should be noted that the CDC has revised its recommendations to say that mRNA vaccines (Pfizer-BioNtech, Moderna) are preferred over the Johnson & Johnson vaccine, citing increasing evidence of a rare blood clotting disorder. (See, “What are the possible side-effects of a COVID-19 vaccine?” below for more information.)

Experts say that those with weakened immune systems require an additional dose in their primary vaccine series. According to the CDC, these include rheumatology patients being actively treated with high-dose corticosteroids, alkylating agents, antimetabolites, tumor-necrosis factor (TNF) blockers, and other biologic agents that are immunosuppressive or immunomodulatory.

For immunocompromised patients 12 years and older who received an mRNA vaccine (only Pfizer-BioNtech is approved for children 12 and older), the CDC recommends a third vaccine dose at least four weeks after the second dose. All doses should be completed with the same product (i.e, all three doses with Pfizer-BioNtech OR all three doses with Moderna). The CDC also recommends third doses of the Pfizer-BioNtech vaccine for some immunocompromised children 5 to 11 years old, depending on their health status. Talk to your child's doctor about a third dose if you believe they may qualify.

This guidance differs from recommendations about boosters, which aim to restore immunity after the primary vaccination series.

However, some experts, including Dr. Anthony Fauci, the White House Chief Medical Advisor, say it's just a matter of time until the definition of being "fully vaccinated" changes from two to three mRNA doses for all. This is partly due to evidence pointing to waning immunity from two doses and the arrival of the Omicron variant (see, Do the COVID-19 vaccines protect against the variants?, for more information, below).

As such, the CDC has updated its guidance to say that all COVID-19 vaccine recipients (Pfizer-BioNtech, Moderna and J&J) ages 18 years and older should receive a booster shot. Children 12 years and older are also eligible to receive a booster shot of the Pfizer-BioNtech vaccine.

Recipients of the Pfizer-BioNtech vaccine are advised to receive a booster shot five months after completing their initial vaccination series; Moderna recipients six months after their second shot; and J&J recipients, including immunocompromised patients, should receive a booster dose at least two months after their first shot.

Any of the approved vaccines (Pfizer-BioNtech, Moderna and J&J) may be used as a booster dose. However, some evidence suggests that J&J recipients who receive an mRNA booster may have improved immunity. Still, there is no official recommendation about which vaccine J&J recipients should receive, and patients should talk to their doctors about which second vaccine dose is right for them.

Additionally, the CDC recommends that immunocompromised individuals 18 and older who have already received three doses of an mRNA vaccine should receive a fourth booster dose six months after their third shot. (Immunocompromised patients 16 and 17 years old may receive a fourth dose). Patients can choose any of the three vaccines (Pfizer-BioNtech, Moderna or J&J) for their booster shot. However, immunocompromised patients who received J&J are not advised to seek out a third booster dose at this time. Likewise, immunocompromised children under 15 are not advised to seek fourth doses at this time. 

Health experts advise against getting additional doses or boosters that differ from what is recommended by the CDC or FDA without the supervision of a doctor. If you have concerns about vaccine protection, talk to your doctor about the best approach. 

Question: What are vaccine guidelines for immunocompromised patients seeking a third dose?

A: Immunocompromised patients who received one of the mRNA vaccines are advised to seek third doses at least four weeks after their second shot. If possible, it’s recommended that a third dose match the vaccine previously administered. That is, those who received two doses of the Pfizer-BioNTech vaccine, should stick to the Pfizer-BioNTech vaccine for their third shot, and vice versa for those who received the Moderna shot.

For immunocompromised patients who received the Johnson & Johnson vaccine, the CDC recommends that they should receive a second shot at least two months after their first. Patients can choose the COVID-19 vaccine of their choice (a second J&J or an mRNA vaccine), though some evidence suggests mRNA booster may improve immunity. There is no official recommendation and patients should consult their doctors about which second dose is right for them.

The CDC recommends that immunocompromised patients who received an mRNA vaccine should receive a fourth booster dose (Pfizer-BioNTech, Moderna, J&J) at least six months after vaccination. This does not apply to immunocompromised patients who received the J&J vaccine – those patients are only advised to seek two total vaccine doses at the time. Talk to your doctor to determine which vaccine booster is right for you. 

Data shows that immunocompromised individuals, such as cancer patients, organ transplant patients and those on immunosuppressive medications, experience blunted vaccine response. But vaccine response in immunocompromised patients can vary, depending on the medications they take and the health conditions they have.

“Not all medications that our patients take have been shown to have significant effects on responses to vaccination. Patients should ask their provider if they are likely to see a beneficial effect from additional vaccination,” says American College of Rheumatology president, David Karp, MD, PhD. “Luckily, we have not seen any safety signals in patients with autoimmune and rheumatic diseases from the COVID-19 vaccines, so there should be no concern for the third dose.”

It also remains unclear how much protection a third dose or fourth booster provides immunocompromised individuals. As such, patients who receive additional doses should still take extra precautions, such as physical distancing and wearing masks, says Karp.

Question: Do the COVID-19 vaccines protect against the variants?

A: Evidence suggests that vaccines provide strong protection against severe disease, death and hospitalization among the primary variants in the United States, Delta and Omicron.

While vaccines appear to be are less protective against infection for the Omicron variant, evidence suggests that third doses of the Pfizer-BioNtech and Moderna vaccines deliver stronger protection.

Both Moderna and Pfizer-BioNtech are already working on developing variant-specific boosters in case they are needed, and could be available in the spring.

That said, experts are urging people to get their boosters now instead of waiting for an omicron-specific booster. Given the uncertainties and potential transmissibility of the virus, they say "we may not have time to wait." Plus, boosters increase the level of disease-fighting antibodies which can help bolster protection against the variant, virologist Pei-Yong Shi at the University of Texas Medical Branch in Galveston, who works with Pfizer, told NPR.

As such, the CDC updated its guidance to say that all COVID-19 vaccine recipients 18 years and older should receive a COVID-19 booster. Children 12 and older may receive booster doses of the Pfizer-BioNtech vaccine.

Immunocompromised individuals have another set of vaccine and booster recommendations to enhance protection. Even so, these recipients may experience a blunted vaccine response and may want to stick with a more cautious approach, including social distancing and wearing masks in settings where vaccination status is unknown. The Arthritis Foundation strongly advocates for vaccination and encourages everyone to seek out the recommended number of primary vaccine and booster doses. If you haven’t already done so, talk to your doctor about receiving additional vaccine doses to maximize protection. 

Question: Will my arthritis drug reduce the COVID-19 vaccine response?

A: Although research is limited, there is evidence that disease modifying drugs used for autoimmune arthritis may reduce the response of the mRNA COVID-19 vaccines from Pfizer/BioNTech and Moderna. No research on the adenovirus J&J vaccine has been reported.

Based on a small study of 133 fully vaccinated individuals taking immunosuppressive medications, antibody levels and virus neutralization was three times lower than in individuals not taking these medications. The study has not been peer reviewed.

However, study coauthor Alfred Kim MD, PhD, Assistant Professor, Division of Rheumatology, Washington University School of Medicine noted in an interview with Reuters that, “most patients in the study were able to mount antibody responses in response to SARS-CoV-2 vaccination, which is reassuring."

Study results showed:

• More modest reductions in patients using TNF inhibitors, methotrexate and sulfasalazine, JAK inhibitors and IL-12/23 inhibitors.
• A 10-fold reduction in patients who used corticosteroids regularly.
• A 36-fold reduction in patients who use B cell inhibitors.

Learn more about study results here.

Question: What are the possible side effects of a COVID-19 vaccine?

A: COVID-19 vaccines can cause mild side effects, such as pain, redness or swelling where the shot was given, fever, fatigue, headache, chills and muscle or joint pain. These side effects are normal and signs that your immune system is building protection against the virus. Most side effects occur within the first three days of vaccination and usually only last a day or two.

These side effects can mimic symptoms of COVID-19. Get tested and self-isolate if you experience symptoms more than three days after being vaccinated lasting more than two days. 

However, on December 16, the CDC revised its vaccine recommendations to say that mRNA vaccines be preferred over the Johnson & Johnson vaccine. The CDC cited increasing evidence showing that the vaccine may trigger a rare blood clotting disorder that has resulted in dozens of cases and at least 9 deaths in the United States. The risk was greatest among women 30 to 49, affecting an estimated 1 in 100,000 who had received the company’s shot.

Likewise, in its fact sheet about the Johnson and Johnson vaccine, the FDA lists warnings for two serious side effects: blood clots and Guillain-Barre syndrome, a potentially serious neurological condition.

Signs of a blood clot include a severe headache that persists, severe abdominal or leg pain that won’t go away or shortness of breath. If you received the vaccine within the last 30 days and are experiencing any of these symptoms, contact your doctor immediately. If you received the vaccine more than a month ago, the risk for blood clot complications is very low, according to Dr. Anne Schuchat, principal deputy director of the US Centers for Disease Control and Prevention.

Symptoms of Guillain-Barre Syndrome usually appear within 42 days of vaccination. Talk to your doctor right away if you begin to experience weakness or tingling in your arms and legs, double vision or difficulty walking, speaking, chewing, swallowing or controlling your bladder or bowels.  

While these side effects can be serious, experts note that they are extremely rare, and that the benefits of getting the J&J vaccine still vastly outweigh the risks of not getting vaccinated at all.  

Neither the Pfizer or the Moderna vaccines are associated with the risk of blood clotting. However, about 1200 cases of heart inflammation (myocarditis) and pericarditis have been reported following vaccination with one of the mRNA vaccines (Pfizer and Moderna). Young adult males under 30 seem to be most at risk, and most cases occurred after the second dose. Most cases were mild, with symptoms like fatigue, chest pain and abnormal heart rhythm that cleared up on their own.

Experts stress that the benefits of vaccination strongly outweigh the risks and that COVID-19 infection is a major risk factor for heart inflammation and heart damage. In other words, the chances that an unvaccinated person who contracts COVID will experience heart problems is much greater than someone who gets vaccinated with one of the mRNA vaccines.

Others who have received mRNA COVID-19 vaccines have experienced severe allergic reactions (anaphylaxis). These events are very rare. The CDC estimates that the rate of anaphylaxis is 11.1 per million doses of the Pfizer-BioNTech vaccine and 2.5 cases per million doses of the Moderna vaccine. Another study, published as a research letter in JAMA, says that the risk of having a severe allergic reaction to the vaccine is “extremely low,” highlighting the overall safety of mRNA vaccines.

Experts urge that the fear of anaphylaxis should not deter people from getting vaccinated. The risk of developing severe outcomes from COVID-19 is much higher than the risk of an allergic reaction from the vaccine.

Still, healthcare workers must be prepared to treat reactions in the rare event they occur. As such, patients are asked to stay for 15 minutes to be monitored after vaccination – which is when most allergic reactions occur.

Those with a history of severe allergic reactions not related to vaccines or injectable medications may still get the vaccine. However, these patients are advised to be monitored for at least 30 minutes after vaccination.

Patients with a history of immediate allergic reactions to vaccines and injectable medications should discuss the risks with their doctor. The CDC advises patients to avoid vaccines containing ingredients that have given them previous severe allergic reactions.

There are two main allergens of concern in the COVID-19 vaccines:

• Polyethylene Glycol (PEG), which is found in the mRNA vaccines. If you are allergic to this ingredient, ask your doctor about getting the J&J vaccine
• Polysorbate, which is found in the J&J vaccine.  Ask your doctor if you can get an mRNA COVID-19 vaccine if you are allergic to this ingredient.

Finally, if you have an immediate allergic reaction after getting the first dose of a COVID-19 vaccine, the CDC advises against getting a second dose.

Question: Which vaccines have been FDA approved and what does that mean?

A: On August 23, the Food and Drug Administration (FDA) formally approved the Pfizer-BioNTech vaccine for people 16 years and older, after granting it emergency use authorization (EUA) last December. The Pfizer-BioNtech vaccine is the first COVID-19 vaccine on the market to be given full FDA approval. The vaccine is still authorized for emergency use in children ages 5 to 17.

FDA approval makes it easier for employers, universities, the military and other institutions to mandate vaccination. It also gives doctors more flexibility to prescribe third doses of the Pfizer-BioNTech vaccine to patients. 

In the meantime, health experts say that FDA approval of the Pfizer-BioNTech vaccine doesn’t undermine the safety and efficacy of the Moderna and Johnson & Johnson vaccines. All three vaccines have met the FDA’s rigorous and scientific standards for EUA, says FDA Commissioner, Janet Woodcock, MD. Rather, FDA approval is another important step in reassuring the public that vaccines are safe and effective, she says. 

"Real-world data has shown that patients with rheumatic diseases have worse outcomes than the general population when becoming ill with COVID-19," says David Karp, MD, president of the American College of Rheumatology. "We are hopeful the FDA’s formal approval of the Pfizer vaccine will help Americans feel more confident in the safety and efficacy of mRNA technology and will encourage them to pursue vaccination to reduce their risk of developing COVID-19 disease." 

Moderna submitted its application for full approval in June, about a month after Pfizer-BioNTech, and regulators are still reviewing data. Johnson & Johnson is expected to appply for full FDA approval soon.

Question: What is the difference between an mRNA vaccine and an adenovirus vaccine?

A: The vaccines from Pfizer/BioNTech and Moderna, Inc. use a genetic molecule called messenger RNA (mRNA), which teaches our cells how to create a version of the coronavirus spike protein. This prompts the immune system to make antibodies against this spike protein so the body can recognize the virus and fend off future infections.

Because mRNA is so fragile, these types of vaccines must wrap mRNA in oily lipids and store them in very cold temperatures.

Like mRNA vaccines, adenovirus vaccines also teach the immune system how to fight the coronavirus by carrying instructions for building the spike protein. But instead of storing the instructions in the form of mRNA, adenovirus vaccines, like the Johnson & Johnson vaccine, use double-stranded DNA. The DNA is “wrapped” and delivered to the body in the form of a virus, called an adenovirus.

Adenoviruses are common – many cause the common cold and flu-like symptoms. However, the Johnson & Johnson vaccine uses a modified adenovirus that cannot copy itself inside your cells and make you sick.  

Importantly, mRNA and adenovirus vaccines only carry the instructions to build the coronavirus virus spike protein, not the virus itself. This makes it impossible for these vaccines to give you the coronavirus.

While these vaccine technologies are considered newer, scientists have actually been studying them for many years. And unlike traditional vaccines that use weakened live or dead versions of the entire virus, these vaccines are simpler to produce.

Question: How important is the timing between COVID-19 vaccine doses?

A: The current COVID-19 vaccines available in the U.S. require two shots either 21 days (Pfizer/BioNtech) or 28 days (Moderna, Inc.) apart.

The FDA, CDC and other health experts stress that it’s essential to get fully vaccinated as close to the recommended dosing intervals as possible. In other words – don’t delay scheduling your second appointment longer than necessary. If you are able to get the COVID-19 vaccines in the 21-day (Pfizer/BioNTech) or 28-day (Moderna, Inc.) windows, or close to them, do so.

The CDC has guidance for those who are unable to get their second shot at the recommended dosing intervals.

• Second doses received up to four days earlier than the recommended intervals for both vaccines are still considered valid; 17 -21 days for Pfizer/BioNtech and 24-28 days for Moderna, Inc.
• Second doses received six weeks (42 days) after the initial dose for either vaccine are still considered valid.

Question: Are COVID-19 vaccines safe for people with autoimmune disease?

A: There is no advisory against vaccinating people with autoimmune diseases, and experts say there is no reason to believe that the current COVID-19 vaccines on the market are unsafe for these populations.

Both the Pfizer/BioNTech and Moderna, Inc. vaccines are made with mRNA technology, which contain genetic instructions for one part of the coronavirus instead of the entire virus itself. Experts, including Wilbur Chen, MD, vaccine researcher, professor of medicine at the University of Maryland School of Medicine, and Ted Mikuls, MD, MSPH, Umbach Professor of Rheumatology at the University of Nebraska, expect that vaccines made with this technology to be safe for immunocompromised patients and those on immunosuppressant drugs.

However, Mikuls adds that more data is needed understand whether immunosuppressant medications or unchecked disease activity may reduce vaccine effectiveness. Even so, he anticipates the vaccine will provide protection for the vast majority of patients with arthritis and rheumatic diseases.

Experts urge that immunocompromised patients don't delay vaccination, including third doses. 

Some DMARDs have been shown to blunt immune responses to other vaccines such as those for influenza, pneumonia and Hepatitis B.  Whether holding or delaying DMARD therapies might lead to improved vaccine responses with available and emerging COVID vaccines is currently unknown.

The American College of Rheumatology (ACR) has released vaccine clinical guidance for rheumatologic patients. 

As data continues to be collected on the effects of vaccines for patients with autoimmune disease, talk to your health care provider about the considerations about getting vaccinated.

Question: Why do some people feel sick after a COVID-19 vaccine? 

A: Some people who received the vaccine have had flu-like symptoms, including, body aches, chills and fever. If you experience these side effects, it's a normal response and a sign that your body is building a protection against the virus. In clinical trials, some participants experienced more side effects after the second dose.

Question: Can the vaccine give me COVID-19?

A: The vaccine cannot give you the virus. This is true of traditional vaccines made from dead viruses, and almost always true of live, attenuated vaccines, which in rare cases, can cause mild illness in some vulnerable populations. What’s more, the current vaccines on the market (Pfizer-BioNtech and Moderna, Inc.) do not contain the entire virus, only genetic instructions for one part of the virus, so it’s impossible for these vaccines to give you COVID-1. 

Question: How long does it take to develop immunity after receiving a COVID-19 vaccine?

A: The new COVID-19 vaccines teach your immune system to recognize and fight the virus. This protects you from getting sick with COVID-19.  But a vaccine needs time to provide protection after it’s received. COVID-19 vaccines may not protect you until a week or two after your second shot or third shot. The same time frame applies to enhance immunity after your booster dose. 

Remember, you could be infected with the SARS-CoV-2 virus just before or just after vaccination and get sick. So, it’s very important to continue the usual risk mitigation activities – wearing a mask, physical distancing, hand hygiene, etc.

Question: Can I get infected with COVID-19 after I get vaccinated?

A: The short answer is yes, but all three COVID-19 vaccines on the market provide exceptional protection against severe illness and hospitalization. 

Many people think of vaccines as shields from viruses, but this isn’t always the case. For some, vaccines only protect against symptoms and disease, not necessarily infection. In other words, it’s possible that a vaccinated person may still get infected with a virus but not get sick or only experience mild or moderate symptoms.

Although vaccines don’t always prevent infection, they prime your immune system to quickly fight the virus and protect you from the worst outcomes of disease.

It should be noted, however, that vaccine protection may be reduced in people with compromised immune systems, such as those taking immunosuppressive drugs. As such, health experts recommend that people with compromised immune systems receive third doses at least four weeks after their second shot and a fourth booster shot at least six months after their third. For J&J recipients, patients are advised to seek a second dose of their choice (J&J or an mRNA vaccine) at least two months after their first. There is no recommendation about boosters for J&J recipients at this time.

Immunocompromised patient  are also encouraged to practice more caution, such as limiting time in crowded indoor spaces and practicing social distancing.

Question: Can I still spread COVID-19 after getting vaccinated?

A: It’s possible, but less likely. Vaccines sharply reduce the chance of becoming infected with COVID-19. But in the event of a breakthrough infection from the delta variant, internal data from the CDC suggests that fully vaccinated people may be just as contagious as unvaccinated people with infections. As such, the CDC now recommends that even vaccinated people wear masks indoors in areas of the country where the virus is surging.

Question: Will a COVID-19 vaccine alter my DNA?

A: No. COVID-19 mRNA vaccines do not change your DNA in any way. The term mRNA means messenger RNA vaccines.  These vaccines teach your cells how to make a specific protein that triggers your immune system to fight back against the COVID-19 virus and protect against future COVID-19 infections. The mRNA never enters the nucleus of your cells where your DNA is located. Learn more about COVID-19 mRNA vaccines.

Question: Are vaccines recommended for people who have already had the virus or have tested positive for antibodies?

A: The short answer: yes. Researchers say there are still too many unknowns about how long immunity lasts from natural infection. Though immunity from COVID-19 vaccines is yet to be determined, research shows that vaccine immunity tends to be stronger than natural immunity. However, the Mayo Clinic advises that those who have been recently diagnosed or exposed to the virus should delay vaccination or wait about 90 days from the time of diagnosis to get vaccinated. 

Question: Are the COVID-19 vaccines safe for children with JA?

A: See: COVID-19 FAQS: Juvenile Arthritis.