COVID-19 Vaccine Frequently Asked Questions
How do vaccines work?

Vaccines trigger the body’s natural response to fight illnesses.  Vaccines work by training the immune system to be ready to recognize viruses or bacteria when they enter the body. Then, if a person is exposed to that virus or bacteria, their immune system knows how to respond. The COVID-19 vaccines protect people from getting seriously ill and requiring hospitalization. If a vaccinated person gets COVID-19, they usually have mild symptoms.

Are COVID-19 vaccines safe?

Yes. The Federal Drug and Administration (FDA) works to make sure that all vaccines are as safe as possible through careful testing. Although COVID-19 vaccines are new, the process for ensuring vaccine safety is not new. All vaccines must meet strict safety standards before being released to the public. Many thousands of adults of different ages and races volunteered for clinical trials to test the COVID-19 vaccines, and over 80% of Californians 12 years and older have completed their primary series. The FDA and others continue to track side effects and watch for any safety concerns.

What’s in the COVID-19 vaccines?

The Moderna and Pfizer vaccines have mRNA, genetic material that our cells use to make spike proteins. Then our bodies respond by making antibodies. The mRNA COVID-19 vaccines do not have preservatives, which is why they must stay frozen until they are ready to use. The Johnson & Johnson vaccine has a modified adenovirus that delivers instructions for the body to make antibodies. Novavax is a protein-based vaccine. Novavax stimulates an immune response using a technique that is well-known and established. It is similar to other common vaccines you may have had such as seasonal flu, pertussis, and hepatitis B.  Vaccines may also have lipids, salts, sugars, acids, and acid stabilizers to help keep them stable to deliver the active ingredients. Vaccines do not contain ingredients that are poisonous or harmful.

Who can get a COVID-19 vaccine?

People 6 months and older can get a COVID-19 vaccine.

What COVID-19 vaccines are available?

•    The FDA has given full approval for the Pfizer vaccine for people 12 years and older and the Moderna vaccine for people 18 years and older. Children 6 months and older can get the Moderna and Pfizer vaccines under emergency use authorization.
•    The FDA has given emergency use authorization for the Novavax COVID-19 vaccine. People 18 years and older can get two doses of Novavax spaced three weeks apart as a primary series and a Novavax booster six months after. Novavax offers an alternative to the mRNA vaccines for people who cannot or prefer not to get an mRNA vaccine.
•    The FDA has limited the use of the Johnson & Johnson COVID-19 vaccine because of potential health risks. In most cases, another vaccine is preferred.

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

Yes. Omicron strains spread easily and breakthrough cases occur.  However, vaccines continue to protect people from becoming very sick, being hospitalized, or dying from COVID-19. Even with new strains, getting vaccinated is a safe and reliable way to protect yourself from COVID-19. The virus may change again over time creating new variants. Scientists will continue to monitor these variants.

How is the bivalent booster different than the original (monovalent) COVID-19 booster?

The original (monovalent) COVID-19 boosters only target the original strain of the virus. The updated bivalent booster targets both the original strain and newer omicron strains. The bivalent boosters offer better protection against the types of COVID-19 you’re most likely to be exposed to now and in the near future. COVID-19 vaccination and boosters continue to be the most important strategy to prevent serious illness and death from COVID-19.

When can I get a bivalent booster?

Get your booster as soon as possible. Bivalent boosters are available for everyone 6 months of age and older.

  • Children ages 6 months and older can get a bivalent vaccine. The Moderna COVID-19 bivalent vaccine booster is authorized for people six months and older at least two months after they complete their primary series. Children 6 months through 4 years old who are currently receiving their Pfizer primary series will receive a Pfizer bivalent vaccine as their third primary series dose. Children 6 months through 4 years old who completed their Pfizer monovalent series more than two months ago can get a Pfizer bivalent booster.
  • People 18 years and older can get either a Moderna bivalent or a Pfizer bivalent booster at least two months after getting their primary series or their most recent booster. This age group can also mix or match their boosters. A Pfizer or Moderna booster is strongly advised for those who got the Johnson & Johnson vaccine. Novavax vaccine is authorized for use as a booster for people who have completed their primary series.
How long will the COVID-19 booster protect me?

The COVID-19 boosters offer the best protection against getting sick with COVID-19 in the months following the shot. Two weeks after getting the vaccine the risk of getting sick is low and the risk gradually goes up over the first six months. However, the vaccine and boosters will continue to provide long-term protection against severe disease, hospitalization, and death.

Are there side effects?

Yes. The most common side effect is pain in the arm where you get the vaccine. Some people also have one or more of these symptoms: tiredness, headache, muscle pain, chills, joint pain, and fever. Another side effect is swollen lymph nodes in the neck or under the arm where the vaccine was given. These are all signs of the body’s immune system working. A very small number of the many people vaccinated have had more serious side effects such as a severe allergic reaction.  Talk to your health care provider if you have had a severe allergic reaction to other vaccines or any ingredients in the COVID-19 vaccines. Your health care provider can help you decide if it is safe for you to receive the COVID-19 vaccine.

Should people who have already had COVID-19 get the vaccine?

Yes. People who have had COVID-19 may have some immunity against the coronavirus, but this immunity can be weak and may not last long. Most people develop more antibodies to the coronavirus after they are fully vaccinated than after getting COVID-19. The vaccine will help your body have a stronger response if you get COVID-19 again. People with COVID-19 should wait until they are no longer infected, and check with their health care provider before getting the vaccine.

Do I still need to wear a mask after I’ve had the vaccine?

It depends on your personal risk and your community levels of COVID-19. Follow public health recommendations for wearing a mask if:
•    community levels are high, or
•    your child care program is experiencing a COVID-19 outbreak, or
•    you are at risk for severe disease or are immunocompromised.
Check the CDC website for information about community levels of COVID-19 in your county.

Where can I get a vaccine?

This will vary by county. You can get a vaccine from local pharmacies like CVS or Walgreens, or from your health care provider. Your local health department or school district may also be holding vaccination clinics.  Check with your local public health department or primary care provider about where the vaccine is be available in your location.

What does the vaccine cost?

Most health care plans and county health departments provide the vaccine free of charge.

Is the vaccine required for child care workers?

Getting a COVID-19 vaccine is voluntary, but some employers require vaccination for their workers. Some public venues may also require proof of vaccination for entry.

Is the vaccine recommended for pregnant people?

Yes. The COVID-19 vaccination is recommended for pregnant people. The CDC recommends that all people who are pregnant, breastfeeding, trying to get pregnant, or might become pregnant in the future be vaccinated for COVID-19. Pregnant people are more likely to get severely ill if they get COVID-19 compared with non-pregnant people. People who contract COVID-19 while pregnant also face a higher risk of having a preterm birth. Getting a COVID-19 vaccine during pregnancy can also help protect the baby from COVID-19. Pregnant people should talk to their health care providers about getting the vaccine.

Updated March 22, 2023, UCSF California Childcare Health Program

This article was made possible with funding from the Heising-Simons Foundation.