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There’s been quite a bit of discussion about what to do leading up to getting a COVID-19 vaccine — like what to consider if you’re immunocompromised, how to talk to your doctor about the vaccine and medications like rituximab, or what to know if you’re concerned about allergic reactions.
However, once you’ve decided to get the vaccine when it’s available to you, what happens after you receive that long-awaited shot?
Unfortunately, the vaccination won’t work like a light switch to flip off your risk for COVID-19 right away. And it’s possible that you’ll experience some side effects.
Here is exactly what you should do from the moment you receive your vaccine and onward to monitor for symptoms and protect yourself from future coronavirus infection.
15 to 30 Minutes After Getting Your COVID-19 Vaccine
After you receive your vaccine, expect to hang around the health care facility for 15 to 30 minutes. The U.S. Centers for Disease Control and Prevention (CDC) states that people who have a history of anaphylaxis due to any cause should be observed for 30 minutes following vaccination, while everyone else should be observed for 15 minutes.
The staff will monitor all vaccine recipients for any signs of allergic reactions. There should be epinephrine on hand if a severe reaction were to occur. Know that severe allergic reactions to COVID-19 vaccines are very rare, even though those that have occurred have received a lot of attention.
From December 14 to 23, 2020, there were just 21 cases of anaphylaxis after administration of a reported 1,893,360 first doses of the Pfizer COVID-19 vaccine, according to data published in the CDC’s Morbidity and Mortality Weekly Report. That equates to 11.1 cases per million doses of the vaccine. In that same time period, there were 83 cases of non-anaphylaxis allergic reaction reported.
More than 70 percent of the anaphylaxis cases occurred within 15 minutes of vaccination, which is why you’ll need to stay to be monitored after your shot.
Preventing COVID-19 Infection While You Wait
Make sure to wear a mask properly (covering your mouth and nose and fitting snugly) and stay socially distanced while you wait after getting your shot. Some locations even offer vaccines via drive-through, so you can stay in the car.
If you practice standard coronavirus mitigation methods like wearing your mask, social distancing, and using good hand hygiene, you likely don’t need to be overly concerned about contracting COVID-19 at your vaccination site.
“Going to a location to get a vaccine is in and of itself a relatively low-risk venture, especially if small groups of people can get in, get their shot, be observed for the required period of time, and then exit,” says David Aronoff, MD, Director of the Division of Infectious Diseases at Vanderbilt University School of Medicine in Nashville, Tennessee. “It’s very likely that the people administering the vaccine will have good personal protective equipment and probably will have already themselves been vaccinated.”
1 Hour After Getting Your COVID-19 Vaccine
When you receive the COVID-19 vaccine injection in your arm, it begins a cascade of responses in your body that eventually make it easier to fight off the coronavirus if you’re exposed.
However, this immune system response doesn’t happen instantly — it takes time to build up. And you’ll need the second booster shot to get the vaccine’s full efficacy, which is about 95 percent for the Pfizer and Moderna vaccines currently available in the U.S.
After you get vaccinated, you may be tempted to visit loved ones or be a little less strict about wearing a face mask. However, you won’t be protected yet, and you’ll need to still follow mitigation efforts (more on that later). Remember: It is possible to contract COVID-19 after receiving your first vaccine dose (and there have been reports of this among health care workers), so stay vigilant.
“The process of going from that first shot to having some immune protection appears to take a couple of weeks,” says Dr. Aronoff.
To understand why, it’s important to know how the vaccine works. Here’s how Dr. Aronoff explains it: If you were to look at the virus under the microscope, you’d see that it has little spikes that look like a crown, which is how the coronavirus gets its name (“corona” means “crown”).
Those spikes act like Velcro to allow the virus to stick to our cells, invade them, and cause infection. Injecting small pieces of the virus’s genetic material (or RNA) into our muscles through a vaccine teaches our body to produce antibodies whenever it sees that spiky virus.
The antibodies bind to the spike proteins, which helps neutralize the virus if you were to come in contact with it. Imagine petroleum jelly coating the Velcro, causing it to lose its stickiness.
However, since this process takes weeks to ramp up and requires a second booster shot, you won’t be protected from coronavirus the instant you get your vaccination.
“If we look at the studies from Pfizer and Moderna, and we compare how frequently people got symptomatic COVID-19 after receiving the vaccine or the placebo, those two groups began to noticeably separate about two weeks after the first vaccine injection,” says Dr. Aronoff.
In other words, people who got placebo were clearly experiencing more cases of COVID-19 than the people who got the vaccine, and this difference started to be evident by about two weeks after the first shot.
As your body gears up to produce these antibodies after you get the vaccine, you may have side effects that are normal signs of your body building immunity, per the CDC.
These vaccine side effects include:
- Pain in the arm where you got the shot
- Swelling in the arm where you got the shot
If you have pain or discomfort, speak to your doctor to see if it’s appropriate to take an over-the-counter medicine like ibuprofen or acetaminophen. The CDC recommends against automatically taking these drugs after getting the vaccine “for the purpose of preventing post-vaccination symptoms,” though it says they can be taken to treat symptoms if they develop.
You might also reduce pain and discomfort where you got the shot by applying a clean, cool, wet washcloth over the area or using and exercising your arm.
Call your doctor if the redness or tenderness where you got the shot increases after 24 hours. To reduce fever discomfort, drink plenty of fluids and dress lightly.
Consider signing up for v-Safe, a smartphone-based tool from the CDC that uses text messaging and web surveys to provide personalized health check-ins after you receive a COVID-19 vaccination. V-safe allows you to report any side effects after getting the COVID-19 vaccine; depending on your answers, someone from CDC may call to check on you and get more information. The app will also remind you to get your second COVID-19 vaccine dose.
The health care provider who administered your vaccine may give you instructions about signing up, but if not, you can learn more about it and how it works here.
1 to 3 Days After Getting Your COVID-19 Vaccine
In the days following your vaccination, be on the lookout for any unusual symptoms and call your doctor if they arise.
“My two reasons for calling your physician would be if regular vaccine side effects last longer than two to three days, or if you’re having symptoms that are not common after vaccination, like cough, chest pain, and shortness of breath,” says Elana Oberstein, MD, an internist with a subspecialty in arthritis and autoimmune disease at The Lennar Foundation Medical Center in Coral Gables, Florida, and Senior Medical Director of Musculoskeletal at Modernizing Medicine.
Since you’re not immediately protected after you receive your vaccine, these could be symptoms of COVID-19 or another health issue.
Disease Flares vs. Vaccine Side Effects
It may also be helpful to keep a log of any symptoms you have before your vaccination and after, which will help differentiate vaccine side effects from potential disease flares from an underlying chronic illness. (Using v-safe can help you track vaccine-related side effects.)
“It can be hard to parse out, since muscle soreness, headache, achiness, joint pain, muscle pain, and low-grade fever could be indicative of a rheumatic disease flare, but the critical feature is the length of time,” says Dr. Oberstein. “Flares don’t traditionally last 48 hours and then disappear. What we’re really seeing with this vaccine is a sudden onset of symptoms anywhere from right after the injection to 48 or 72 hours after it, and then they go away.”
The physical characteristics of your symptoms will also likely be different if you’re experiencing vaccine side effects versus a disease flare-up.
“When people have rheumatoid arthritis flares, they may have joint swelling, where you actually see a swollen joint filled with fluid that may be warm or hot to touch,” says Dr. Oberstein. “That is not a vaccine side effect. The joint achiness sometimes caused by vaccines is more of a systemic achiness.” Chills are also vaccine-related and likely not related to a traditional disease flare-up.
If new symptoms persist after your vaccination but you’re not sure what’s causing them, talk to your doctor, who will be able to help determine whether it could be a flare, an infection, a vaccine side effect, or something else altogether.
Rheumatologists don’t have reason to suspect that the COVID-19 vaccine will necessarily trigger an uptick in disease activity or flares, but data is needed to understand how people with autoimmune diseases fare after receiving the vaccine. Read more here about how researchers are starting to collect this information.
3 to 4 Weeks After Getting Your COVID-19 Vaccine
It’s imperative that you return to receive your booster shot so you can benefit from the vaccine’s full efficacy.
- For the Pfizer vaccine, the second dose is given three weeks (21 days) after the first dose.
- For the Moderna vaccine, the second dose is given after four weeks (28 days) after the first dose.
“Once our immune system has seen something foreign like these spike proteins, it develops what we call a memory,” says Dr. Aronoff. “The next time it sees those proteins, it doesn’t take as long to generate an antibody response and it generates a more robust one. When we come back for that second shot, we get an amplified, boosted immune response.”
In the clinical trial that led to its authorization in the U.S., the Pfizer vaccine showed an efficacy of 52 percent after the first dose. Within the first seven days after the second dose, efficacy reached 91 percent, and it reached full efficacy of 95 percent at least seven days after the second dose, per a December 2020 study published in The New England Journal of Medicine.
Meanwhile, the Moderna vaccine provided around 80 percent efficacy one month after the first dose, but reached 94.1 percent efficacy starting 14 days after the second shot, according to the U.S. Food & Drug Administration. Although there appears to be some protection against COVID-19 after a single dose, there is not yet enough information to determine long-term protection beyond 28 days after just one dose.
Even though there is debate about delaying second doses of the vaccines (and some other countries have started implementing delays) in order to vaccinate more people more quickly, this is not approved policy in the U.S. right now.
In the trials for the COVID-19 vaccines, side effects were more common after the second dose than after the first. So even if your side effects were very mild the first time around, be prepared that you could experience different or stronger symptoms after your second dose.
The Months Beyond Getting Your COVID-19 Vaccine
Although you will be vaccinated, it will still be important to continue to follow COVID-19 prevention tactics for months to come. The general guidance to follow is simple, yet not always easy to adhere to:
- Maintain a social distance of six feet or more from people outside of your household whenever possible.
- Wear face coverings when out in public and when you can’t be socially distant.
- Wash or sanitize your hands frequently and disinfect commonly touched surfaces.
- Avoid large groups or situations when it will be hard to be socially distant.
- When spending time with others, being outdoors is safer than indoors.
You can’t throw caution to the wind because you’re not guaranteed to evade the virus or prevent it from spreading even after you’re vaccinated.
Though more research is needed, “we think the COVID-19 vaccine’s impact may be similar to that of the flu vaccine’s in that if you’re immunized, you may still be able to get infected but you’re less likely to have symptoms or serious illness, the period of time that you spend shedding virus and being contagious is likely to be much smaller, and the amount of virus you’re shedding while you’re contagious is likely to be much less than if you had not been vaccinated,” says Dr. Aronoff.
It may be that the vaccine doesn’t give you an impermeable shield against the virus, but it can certainly help mitigate some dangerous effects if you do contract it.
We also don’t yet know:
- Whether the COVID-19 vaccine prevents asymptomatic transmission
- How long protection from the vaccine lasts
- Whether the COVID-19 vaccine may be less effective if you take immunosuppressant medication, such as disease-modifying antirheumatic drugs (DMARDs)
Researchers are actively studying this now. Most people on immunosuppressant medication should still get the vaccine, but it’s important not to have a false sense of security about being protected from the coronavirus until we know more.
When Might ‘Normal Activities’ Resume?
It’s important for everyone to collectively take steps to mitigate the pandemic, something that becomes more difficult when some people follow public health measures and others do not.
“We need to continue to model good behavior for everybody who is not vaccinated,” says Dr. Aronoff. “If we start to see people in public places who are not wearing masks and not socially distancing, we don’t know if that’s because they are ignoring public health policies — or if it’s because they feel like they don’t have to follow them because they’re vaccinated. Either way, it sends a message that’s confusing.”
In terms of when we’ll be able to return to our normal routines, two major things need to be considered. First, we need to see that cases of COVID-19 are very low in our communities, which we’ll learn by looking at the results of testing.
“If we see dramatic reductions in the numbers of new cases per 100,000 people per day in our communities, great reductions in the percentage of tests that are coming back positive, and great reductions in the number of people who are being hospitalized with COVID-19, that will be probably the most important sign that we can continue to reopen businesses and get people back together,” says Dr. Aronoff.
The Role of Herd Immunity
The second important piece of the puzzle is getting as many people as possible immunized so that these important metrics do not start to increase as we reopen.
“The SARS-CoV-2 virus is a high transmissible virus,” said Soumya Swaminathan, MD, Chief Scientist at the World Health Organization (WHO), in an August 2020 episode of the WHO podcast Science in 5. “We think it needs at least 60 to 70 percent of the population to have immunity to really break the chain of transmission. If you allow this to happen naturally, it will take a long time, of course, but more importantly, it’s going to do a lot of collateral damage.”
In other words, the vaccine is an important measure in achieving this widespread immunity because letting the virus run wild could result in a very large number of deaths.
That said, even with a vaccine, this will take time. “Even as vaccines start protecting the most vulnerable, we’re not going to achieve any levels of population immunity or herd immunity in 2021,” Dr. Swaminathan said at a January 11 media briefing, per the Washington Post. “Even if it happens in a couple of pockets, in a few countries, it’s not going to protect people across the world.”
However, eventually reaching these numbers through vaccination along with following standard mitigation measures (wearing face masks, social distancing, and washing hands) is what will help end the pandemic.
“All of these things work together to greatly reduce the risk of coronavirus transmission, and that is how we’re going to end this pandemic the quickest — not by substituting vaccinations for other public health measures, but rather by combining vaccinations with these public health measures,” says Dr. Aronoff.
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CDC COVID-19 Response Team and Food and Drug Administration. Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Pfizer-BioNTech COVID-19 Vaccine — United States, December 14–23, 2020. Morbidity and Mortality Weekly Report (MMWR). January 6, 2021. doi: http://dx.doi.org/10.15585/mmwr.mm7002e1.
D’Ambrosio A. Vaccinated but Sick With COVID-19. MedPage Today. January 7, 2021. https://www.medpagetoday.com/infectiousdisease/covid19/90584.
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Interview with David Aronoff, MD, Director of the Division of Infectious Diseases at Vanderbilt University School of Medicine in Nashville, Tennessee
Interview with Elana Oberstein, MD, an internist with a subspecialty in arthritis and autoimmune disease at The Lennar Foundation Medical Center in Coral Gables, Florida, and Senior Medical Director of Musculoskeletal at Modernizing Medicine
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U.S. Food & Drug Administration. Vaccines and Related Biological Products Advisory Committee Meeting. December 17, 2020. https://www.fda.gov/media/144434/download.
V-safe After Vaccination Health Checker. COVID-19. U.S. Centers for Disease Control and Prevention. January 12, 2021. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/vsafe.html.
Vaccine Safety Monitoring and Reporting in Your Facility. Vaccines & Immunizations. U.S. Centers for Disease Control and Prevention. December 23, 2020. https://www.cdc.gov/vaccines/covid-19/toolkits/long-term-care/safety-monitoring-reporting.html.
What to Expect After Getting a COVID-19 Vaccine. COVID-19. U.S. Centers for Disease Control and Prevention. January 11, 2021. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/expect/after.html.