COVID-19 Vaccine: What You Need to Know

In clinical trials for vaccines produced by pharmaceutical companies Pfizer and Moderna, participants did not experience any life-threatening events that were attributed to the vaccine. A risk of a rare condition called thrombosis with thrombocytopenia syndrome (TTS) has been reported following vaccination with the Johnson & Johnson/Janssen COVID-19 Vaccine. TTS is a serious condition that involves blood clots with low platelet counts. This problem is rare, and most reports were in women between 18 and 49 years old. For women 50 years and older and men of any age, this problem is even more rare.

No. COVID-19 vaccines are part of the most intensive vaccine safety monitoring effort in U.S. history, according to the Centers for Disease Control and Prevention (CDC). COVID-19 vaccines were evaluated in tens of thousands of clinical trial participants in order to meet the Food and Drug Administration’s (FDA) rigorous scientific standards for safety, effectiveness and manufacturing quality needed to support emergency use authorization (EUA).

On Aug. 23, 2021, the FDA officially approved the Pfizer-BioNTech vaccine in individuals age 16 and older. The vaccine now will be marketed as Comirnaty.

Over 346 million doses of COVID-19 vaccine have been given in the U.S. as of Aug. 2, 2021, since they were authorized for emergency use by FDA. The vaccines will continue to undergo safety monitoring that includes using both established and new safety monitoring systems to make sure that COVID-19 vaccines are safe.

Viruses constantly change through mutation, and multiple COVID-19 mutations are circulating around the world. Some variations appear to spread more easily or make it resistant to treatments or vaccines. According to the CDC, COVID-19 vaccines are effective against severe disease and death from variants of the virus that causes COVID-19 currently circulating in the United States, including the Delta variant.

Experts don’t know how long protection lasts for those who are vaccinated. Experts are working to learn more about both natural immunity and vaccine-induced immunity. Keck Medicine will continue to monitor data as it becomes available.

Yes. Infections happen in only a small proportion of people who are fully vaccinated, even with the Delta variant. When these infections occur among vaccinated people, they tend to be mild and infectious for a shorter period. However, if you are fully vaccinated and become infected with the Delta variant, you can spread the virus to others. People with weakened immune systems, including people who take immunosuppressive medications, may not be protected even if fully vaccinated. As new COVID-19 variants begin to circulate, it continues to be important to follow state and local guidelines to minimize the spread. These guidelines can include masking, social distancing, hand hygiene and monitoring for symptoms of COVID-19 in case of exposure.

You can book your appointment via California’s statewide system, My Turn.

Some physical side effects are normal after receiving the vaccine. People may experience local site inflammation, fever, headaches, muscle pain and body aches. These symptoms are more frequent after the second dose. The symptoms typically resolve within 1-2 days.

Yes. Children 6 months and older are now eligible to get vaccinated against COVID-19. Studies show that COVID-19 vaccines are safe and effective for children and teenagers. Like adults, children and teens may have some side effects after COVID-19 vaccination that most often go away in a few days.

People with underlying medical conditions can receive a COVID-19 vaccine as long as they have not had an immediate or severe allergic reaction to a COVID-19 vaccine or to any of the ingredients in the vaccine. Vaccination is an important consideration for adults of any age with certain underlying medical conditions because they are at increased risk for severe illness from COVID-19.

If you have ever had a severe allergic reaction to any ingredient in a COVID-19 vaccine, the CDC recommends that you should not get that vaccine. You can find the ingredients and more information on the Pfizer-BioNTech COVID-19 vaccine and the Moderna COVID-19 vaccine on the U.S. Food and Drug Administration (FDA) website.

If you have had a severe allergic reaction to other vaccines or injectable therapies, ask your doctor if you should get a COVID-19 vaccine. Your doctor will help you decide if it is safe for you to get vaccinated.

People with a history of severe allergic reactions not related to vaccines or injectable medications — such as allergies to food, pets, venom, environments or latex — may still get vaccinated.

People with a history of allergies to oral medications or a family history of severe allergic reactions, or who might have a milder allergy to vaccines (without anaphylaxis) — may also still get vaccinated.

Yes. The CDC strongly recommends that pregnant people be vaccinated against COVID-19, after new safety data showed that there is no increased risk of miscarriage among those who were immunized during the first 20 weeks of gestation. Previous studies showed it was safe to receive the vaccine later during pregnancy as well as it having no effect on fertility. Organizations including the American College of Obstetricians and Gynecologists also encourage vaccination, saying pregnant people are at increased risk of severe COVID-19 infection, as well as at risk for complications that include preterm birth.

View more frequently asked questions about COVID-19 vaccines and pregnancy.

Current evidence shows that people whose immune systems are compromised may be more at risk for severe COVID-19. The most recent COVID-19 vaccine guidelines from the Centers for Disease Control and Prevention (CDC) state that people who are immunocompromised may receive the vaccine if they do not have any contraindications to vaccination. People who are immunocompromised should speak to their doctor about the risks and benefits of vaccination, including the potential for a decreased response to the vaccine.

While the most recent COVID-19 vaccine guidelines from the Centers for Disease Control and Prevention (CDC) do not directly address people with cancer, they state that people who are immunocompromised (such as people undergoing cancer treatment) may receive the vaccine if they do not have any contraindications to vaccination. If you are receiving cancer treatment, you should review the risks and benefits of vaccination — including the potential for a decreased response to the COVID-19 vaccine — with your doctor.