COVID-19 Update

Due to interest in the COVID-19 vaccines, we are experiencing an extremely high call volume. Please understand that our phone lines must be clear for urgent medical care needs. We are unable to accept phone calls to schedule COVID-19 vaccinations at this time. When this changes, we will update this website. Our vaccine supply remains limited. Read all COVID-19 Vaccine Information.

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covid19 vaccine what to expect - doctor injecting needle into woman's arm
covid19 vaccine what to expect - doctor injecting needle into woman's arm
covid19 vaccine what to expect - doctor injecting needle into woman's arm

Getting the COVID-19 Vaccine: What to Expect

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As the COVID-19 vaccines are authorized and become more widely available, many are wondering what to expect when they get vaccinated. Lisa Maragakis, M.D., M.P.H., senior director of infection prevention, and Gabor Kelen, M.D., director of Johns Hopkins Office of Critical Event Preparedness and Response, talk about what’s involved in getting vaccinated for COVID-19 and answer some of your most common questions.

When can I get the coronavirus vaccine?

Now that the Food and Drug Administration has issued emergency use authorizations for COVID-19 vaccines, initial quantities of the vaccine are being distributed across the United States.

Because it will take a while to make and distribute enough of the vaccine for everyone who wishes to be vaccinated against COVID-19, the U.S. Centers for Disease Control and Prevention (CDC) is recommending groups of people who should get priority. The CDC has been working closely with state health departments and partners to develop these recommendations.

If you are a Johns Hopkins Medicine patient, visit our COVID-19 Vaccine Information and Updates page for current information on getting vaccinated. Your state’s health department website can also provide updates on vaccine distribution in your area.

How many shots are in the COVID-19 vaccine?

The first two coronavirus vaccines (Pfizer’s and Moderna’s) require two doses given several weeks apart (Pfizer’s second shot is given three weeks after the first, and Moderna’s is four weeks after the first).

COVID-19 Vaccine vials

A One-Shot Vaccine

Learn about the one-shot COVID-19 vaccine from Johnson & Johnson.

What happens if my second dose of the COVID-19 vaccine is delayed?

If you have received the first dose of the Pfizer/BioNTech COVID-19 vaccination, the Centers for Disease Control and Prevention (CDC) states that the second shot should take place three weeks after the first one.

If your first coronavirus vaccine was from Moderna, the CDC says your second shot should be given to you four weeks after the first one.

If something happens that prevents you from getting the second dose of either COVID-19 vaccine on time, you can still receive it up to six weeks (42 days) after the first dose. We are not advocating for people to delay getting their second dose, but the data from clinical trials support this range. There are currently limited data on the efficacy of mRNA COVID-19 vaccines administered beyond this window. According to the CDC, however, if the second dose is administered beyond these intervals, there is no need to restart the series.

What if I received my second vaccination earlier than recommended?

You should not get the second vaccine dose earlier than the recommended times. But, if you’ve already received your second shot, and it was early by 4 days, or less than the recommended time window, your vaccinations are OK, and you do not need to repeat the vaccination series.

Is it OK if my two COVID-19 vaccinations are from different manufacturers?

The Pfizer/BioNTech and Moderna mRNA COVID-19 vaccines are not interchangeable with each other or with other COVID-19 vaccine products. Each vaccine is manufactured differently — even those that use similar underlying technology, such as Pfizer and Moderna. Once you’re given one type of vaccine, the second vaccine dose should be the same type, from the same manufacturer as the first vaccine dose.

Shortly after your first vaccination, your record will show which type you received, so you can schedule your second shot with the same brand and at the proper time interval between doses.

These recommendations may change as further information becomes available or as other vaccine types are authorized for use. In rare cases, such as in the event of an allergic reaction, an exception may be made to allow for the second dose from a different manufacturer.

When will I be protected from catching COVID-19?

The vaccine doesn’t work right away. You are not considered appropriately protected after the first shot. It takes up to two weeks after the second shot for your immune system to fully respond to a vaccine and provide protection against an infectious disease.

Do I still have to wear a mask if I get the COVID-19 vaccine?

For now, yes. Even with a vaccine that is 95% effective, a small number of people who get one of the vaccines will not become immune. It is not yet clear if you can carry the SARS-CoV-2 coronavirus and pass it along to others after getting the vaccine.

Until enough people become immune (either from being vaccinated or by getting and recovering from COVID-19), everyone should follow precautions such as physical distancing, hand-washing and mask-wearing. Vaccinating as many people as possible is a very big job, and it will take months before we can consider cutting back on these basic safety practices.

What are the coronavirus vaccine side effects?

You may have pain in the arm where you got the shot, and you might run a fever and experience body aches, headaches and tiredness for a day or two. The chance of having noticeable side effects is higher after the second shot.

Experiencing side effects does not mean that you have COVID-19, but signals that your immune system is responding to the vaccine. These side effects are considerably less severe or lasting than COVID-19, but if they persist, call your doctor and ask about taking over-the-counter pain and fever reducers to help you feel better.

covid19 vaccine coronavirus - doctor preparing to inject syringe into female patient

Is the COVID-19 Vaccine Safe?

Now that there is an authorized COVID-19 vaccine, our experts answer some frequently asked questions about vaccine safety.

Is it OK to get the COVID-19 vaccine if I have allergies?

While there have been reports of severe allergic-type reactions in a very small number of patients, the CDC says that people with allergies to certain foods, drugs, insects, latex and other common allergens can still get the COVID-19 vaccine.

If you have had a severe allergic reaction (anaphylaxis) to injectables or other vaccines, be sure to discuss the COVID-19 vaccination with your doctor, who can evaluate you and assess your risk. The vaccine provider should observe you for 30 minutes rather than the routine 15 minutes after vaccination, and if you have an allergic reaction to the first shot, you may not receive the second.

The CDC says that at this time, anyone who has a severe allergy (such as anaphylaxis) to any of the Pfizer/BioNTech vaccine ingredients should not get this vaccine.

There is a rumor that taking over-the-counter medications for pain relief before receiving the vaccine lessens its effectiveness. Is this true?

Some studies have suggested that taking medications such as Tylenol or Advil before getting a vaccination might reduce your body’s ability to mount an immune response to the vaccine. It’s unclear if these findings have any clinical significance, though, and other studies did not find any effect of anti-inflammatory medications on the immune reaction to vaccines.

If you regularly take aspirin or other over-the-counter medications such as acetaminophen (e.g., Tylenol), ibuprofen (e.g., Motrin, Advil) or naproxen (e.g., Aleve) for other medical conditions, please continue to do so as directed by your physician or as needed. Otherwise, it’s probably best to not take over-the-counter medications such as acetaminophen or ibuprofen that reduce fever or inflammation before receiving a vaccine. If you are uncomfortable or have symptoms after vaccination, that is the time to take an over-the-counter medication to help you feel better.

How long am I immune after getting the coronavirus vaccine?

This is a question researchers are eager to answer. People who are infected with the coronavirus show a decline in antibodies within a few months, but their immunity may last significantly longer than that. (A few people appear to have caught COVID-19 twice, but this is unusual). Data from the vaccine trials indicate strong immunity at least months after vaccination, indicating possible long-term immunity.

As the SARS-CoV-2 coronavirus has begun to change (mutate), studies are exploring how these changes affect the virus’s characteristics, including its ability to spread between people. A substantial mutation might have an impact on the effectiveness of the vaccines, and vaccine manufacturers are preparing to make adjustments where necessary.

Demographics of the COVID-19 Vaccine Trials

Do I need a coronavirus vaccine if I’ve already had COVID-19?

People who have gotten sick with COVID-19 may still benefit from getting vaccinated. Due to the severe health risks associated with COVID-19 and the fact that re-infection with COVID-19 is possible, people may be advised to get a COVID-19 vaccine even if they have been sick with COVID-19 before.

There is not enough information currently available to say if or for how long people are protected from getting COVID-19 after they have had it (natural immunity). Early evidence suggests natural immunity from COVID-19 may not last very long, but more studies are needed to better understand this.

Does the COVID-19 vaccine interfere with getting a mammogram?

Getting a mammogram too soon after your second dose of the coronavirus vaccine could result in a false positive and a callback due to temporarily swollen lymph nodes.

The Johns Hopkins Division of Breast Imaging supports the recommendation from the Society of Breast Imaging: When possible, and if it does not delay care your doctor recommends, you should schedule screening mammograms before your first dose of a COVID-19 vaccine or four to six weeks after the second dose.

Breast imaging radiologists have noticed that underarm lymph nodes can become temporarily enlarged after a person is vaccinated for COVID-19. This is a normal reaction to the vaccine in some people. Four to six weeks after your vaccine(s), your lymph nodes are expected to return to their normal size.

If you go ahead with getting your mammogram within six weeks of your COVID-19 vaccination and larger-than-usual lymph nodes show up on the test, you will get a callback for more tests. The doctor may follow up with an ultrasound of the lymph nodes under your arm and request that you come in again one to three months after that to be sure the lymph nodes return to their normal size.

If you get a mammogram within the first six weeks after your COVID-19 vaccinations and your mammogram is negative for signs of breast cancer and does not show any enlargement of the lymph nodes, your results would be considered reliable that there are no signs of breast cancer.

scientist with pipette

Coronavirus (COVID-19)

What you need to know from Johns Hopkins Medicine.

Updated: March 2, 2021