COVID-19 Vaccines

Page last updated/reviewed 5/15/2023.

COVID-19 vaccines are safe and effective. The County of San Diego is following federal and state guidelines and working with community partners to provide vaccinations to the public.

Recommendations

For Everyone Aged 6 Years and Older

• Get 1 dose of the updated vaccine which is the (bivalent) COVID-19 vaccine, regardless of whether you have received any original COVID-19 vaccines.  

• Multiple doses, including at least 1 dose of the updated (bivalent) COVID-19 vaccine, depending on the number of doses previously received and age. 
• If a child has not been previously vaccinated, then only use the (bivalent) COVID-19 vaccine.
• See below, or visit the Centers for Disease Control and Prevention (CDC) for the full schedule. 

For People Who May Get Additional Updated COVID-19 Vaccines

People who may be less likely to mount a protective immune response after initial vaccination may receive an additional dose of vaccine, including:

• People aged 65 years and older may get 1 additional dose of COVID-19 vaccine 4 or more months after the 1^st updated COVID-19 vaccine.
• People who are moderately or severely immunocompromised may get 1 additional dose of updated COVID-19 vaccine 2 or more months after the 1^st updated COVID-19 vaccine. Talk to your healthcare provider about additional updated doses.

For People Who May Want Another COVID-19 Vaccine Option

• People 12 years and older who are unable or choose not to get an updated Pfizer-BioNTech or Modern COVID-19 vaccine can consider other options to get up-to-date.
• Visit the Centers for Disease Control and Prevention (CDC) for details.

If You Had or Currently Have COVID-19

• You still need to stay up-to-date with your vaccines. But you may consider delaying your next vaccine dose by 3 months from:
  • When your symptoms started, or
  • If you had no symptoms, when you first received a positive test. 

Stay Up-to-Date

When are you up-to-date with COVID-19 vaccinations?

• Everyone 6 years and older: When you get 1 updated Pfizer-BioNTech or Moderna COVID-19 vaccine.
• Children who are…
  • Aged 6 months to 4 years and got the Pfizer-BioNTech COVID-19 vaccine: When you get 3 COVID-19 vaccine doses, including at least 1 updated COVID-19 dose.
  • Aged 5 years and got the Pfizer-BioNTech COVID-19 vaccine: When you get at least 1 updated COVID-19 vaccine dose.
  • Aged 6 months to 5 years and got the Moderna COVID-19 vaccine: When you get 2 Moderna COVID-19 vaccine doses, including at least 1 updated COVID-19 dose.
  • Aged 6 years and older and got the Moderna COVID-19 vaccine: When you get at least 1 updated COVID-19 vaccine dose.
• People who are unable or choose not to get a recommended mRNA vaccine: When you get the Novavax COVID-19 vaccine doses approved for your age group.

About

There are four approved or authorized vaccines in the United States:

• Pfizer-BioNTech and Moderna COVID-19 vaccines are mRNA vaccines.
• Novavax COVID-19 vaccine is a protein subunit vaccine.
• Johnson & Johnson’s Janssen (J&J/Janssen) COVID-19 vaccine is a viral vector vaccine and can be given in some situations.

These vaccines are given as a shot in the muscle of the upper arm or in the thigh of a young child. COVID-19 vaccine ingredients are considered safe for most people.

How do the COVID-19 vaccines work? 

• The vaccines teach your body to recognize COVID-19, so it is prepared to fight the virus.
• Messenger RNA vaccines (mRNA), like Pfizer-BioNTech and Moderna, provide instructions for your body to build a small protein that looks like a piece of COVID-19. This protein helps your body recognize the virus if you become infected. 
• Protein subunit vaccines, such as Novavax, include harmless proteins of the virus that cause COVID-19. This helps your body recognize the virus if you become infected.
• Viral vector vaccines, like Johnson & Johnson/Janssen, provide instructions to build the spike protein found on the surface of COVID-19. This type of vaccine uses a harmless strand of another virus to deliver the instructions.

How well do COVID-19 vaccines work?

• People who are up-to-date have lower risk of severe illness, hospitalization, and death from COVID-19 than people who are unvaccinated or who have only received the primary series.
• Updated COVID-19 boosters can help build up protection that has decreased since previous vaccination. The updated boosters provide added protection against the recent Omicron subvariants that are more contagious than the previous ones. The recent subvariants, BA.4 and BA.5, are very closely related to the original variant, Omicron, with very small differences between itself and the original variant.

Are COVID-19 vaccines safe?

• COVID-19 vaccines have undergone – and will continue to undergo – the most intensive safety monitoring in U.S. history. 
• Evidence from the hundreds of millions of COVID-19 vaccines already administered in the U.S., and the billions of vaccines administered globally, demonstrates that they are safe and effective.

Are there side effects to the COVID-19 vaccine?

• There may be some mild side effects that go away in a day or two. Side effects are a sign that the vaccine is working. Side effects could include:
  • Pain, redness, or swelling in the arm where you received the vaccine. You can apply a cool, wet washcloth to reduce pain.
  • Mild flu-like symptoms, like tiredness, nausea, muscle aches, chills, headache, or fever. Drink plenty of fluids and rest to feel more comfortable.
• Severe allergic reactions to vaccines are rare but can happen. 

What are booster doses?

• A booster dose refers to a vaccine given after the primary series to boost protection which might have waned over time.

What is the difference between monovalent and bivalent boosters?

• Previous boosters are called “monovalent” because they were designed to protect against the original (i.e., one) virus that causes COVID-19. 
• Updated boosters are called “bivalent” because they protect against both (i.e., two viruses) the original virus and the Omicron variants that causes COVID-19. More recent variants of Omicron are also covered by the vaccine.

Resources

County of San Diego

• COVID-19 Vaccines Frequently Asked Questions
• COVID-19 Educational Materials
• Data Dashboards

California Department of Public Health (CDPH)

• California Scientific Safety Review Workgroup 
• COVID Vaccines are Safe and Effective

Centers for Disease Control and Prevention (CDC)

• COVID-19 Overview of COVID-19 Vaccines
• Ensuring the Safety of COVID-19 Vaccines in the United States
• Myths and Facts
  

Food and Drug Administration (FDA)

• Vaccine Development 101