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COVID-19 Information: Santa Clara County and Bay Area, California

Trustworthy information about COVID-19

Vaccination Updates for the Bay Area, Sept. 2022

As of Sept. 15, 2022, the Bay Area counties have some of the highest vaccination rates in the state (over 87% in Santa Clara County), but lower rates for people vaccinated and boosted (only 69%, by comparison). COVID is still a serious disease, however - it is still the third leading cause of death in the United States, for example.

Initial dose(s) of the COVID vaccine provide significant protection against getting seriously ill, but that protection grows less over time. Public health authorities urge everyone who can to be vaccinated and also to get boosted after 5 months.

Early September 2022, a booster dose that specifically covers multiple variants of SARS-CoV-2 (including the omicron variants) was approved, which may provide significant protection longer, through the peak 2022-23 COVID season, in much the same way that the annual influenza vaccines work. (See below for details on how to get this booster.)

First COVID Vaccination - Bay Area

Currently 3 different vaccines have been approved (on an emergency basis) by the FDA for use by people 18 and older in the U.S.

The vaccines from Pfizer/BioNTech and from Moderna both require 2 doses of the vaccine to be fully effective; the Johnson & Johnson vaccine reaches full effectiveness after just 1 dose. The first two work best if the second dose is 3-4 weeks after the first; if you miss that window of opportunity, it is wisest to get the second dose as soon as possible.

The Pfizer/BioNTech & Moderna vaccines have been approved by the FDA for ages  6 months - 17.  

Boosters and third doses have also been approved  - see below for more details. 

Getting the vaccine - make an appointment or find a walk-in location:

Santa Clara residents  aged 5+ can make an appointment to get the COVID vaccine at any one of several county locations using the links on this website. Some locations offer walk-in vaccinations, no appointment necessary. Stadiums, fairgrounds, community centers, churches, offices and local pharmacies are being added frequently as vaccination sites.

Don't have internet access? Eligible residents can also make appointments for the County HealthSystem vaccine sites through the Valley Connection Call Center at 408-970-2000.  The Call Center is open Monday through Friday from 7am to 9pm and Saturday and Sunday from 8am to 4:30pm. Assistance is available in English, Spanish, Vietnamese, and multiple other languages.

For details on who is currently eligible to be vaccinated, and where, around the Bay Area, check with your healthcare provider (if you have insurance) and with your county health authority.

Vaccinating Kids and Teens: 

Children 6 months - 4 years, and 5 - 11 years old are approved to receive pediatric doses of either the Pfizer/BioNTech or Moderna vaccines. Teens 12-18 are already eligible to  receive the same dose of the Pfizer/BioNTech or Moderna vaccines as adults. All age groups will need 2 doses, roughly 3-4 weeks apart, to be fully vaccinated. 

In Santa Clara County, "All children ages 5-11 who sign up for an appointment are eligible at our mass vaccination sites. ... Drop-in vaccination clinics will provide vaccinations beginning Thursday, November 4, 2021". Teens can also receive theirs at county mass vaccination sites, or any of the other locations where adults are vaccinated. Children younger than 5 years old should be vaccinated at their pediatrician's office. For Santa Clara County residents, if your child does not have a regular doctor, call (866) 967-4677 for assistance enrolling in government programs or health coverage.

Vaccinating any child or teen requires permission of their parent or legal guardian (with some exception for teens 12+). The permission form is online, or can be filled out on location.


In the U.S., COVID vaccines are purchased with taxpayer funds, and are free - but there still might be an administration fee. (The full cost is covered for people without health insurance.)


If you miss the second dose  -- Get the next one as soon as you can. 

If it has been 5 months or longer since your original vaccination -- Get the vaccine booster as soon as you can. 

Boosters and Additional Vaccine Shots

NEW Bivalent boosters were approved in early September 2022, and are now recommended for everyone who is eligible for a booster.

Protection from the first vaccination wanes over time, so in 2022 health authorities recommended that most people get at a booster vaccination dose every 5 months (half the amount of vaccine as the initial full dose). Another full dose is also recommended for everyone who received the single-shot Johnson & Johnson vaccine. The CDC also approved a "mix & match" approach to booster or third doses, meaning that we can safely receive a different vaccine for this purpose. An extra full dose of Pfizer/BioNTech or Moderna has also been approved for people who are immunocompromised.

Santa Clara County Public Health Department urges everyone who is eligible to keep their vaccines up to date.


The new bivalent booster vaccines protect against multiple variants of SARS-CoV-2, including the omicron variants that were so dangerous last winter and spring. It can be taken at the same time as a flu shot (influenza booster) or many other vaccines.

Those who work in a daycare, school, college, or university in CA may be required either to get a vaccine booster or to test for a COVID infection multiple times per week.

California mandates that people who work in high-risk settings in California must be vaccinated and have a vaccine booster if eligible: Per the Santa Clara County Public Health's Order, high-risk settings include:

  • skilled nursing facilities, long-term care facilities, adult day care facilities, and memory care facilities;
  • healthcare delivery facilities (such as hospitals, clinics, medical offices, dialysis centers) where patient care is provided, as well as medical first responders;
  • jails and other correctional facilities; and
  • congregate shelters.

What Happens After Getting a Vaccine?

Information on the side effects of these vaccines, and precautions to take:

one person pointing to recent vaccination + health care worker, from Santa Clara County Dept. of Public Health.

After getting vaccinated, sign up with the CDC's reporting system to record your reactions, and help to push our knowledge of how to treat this novel disease forward. Sign up after the first dose, for 2-part vaccines or after the 1-shot version.

Getting vaccinated now does not mean we can immediately go back to our pre-pandemic life. The hope is vaccines will save lives and keep fewer people from getting seriously ill, but they probably will not be able to stop the pandemic in its tracks quite yet. People who have been fully vaccinated (at least 14 days after their last vaccine dose) have fewer restrictions on wearing face masks and distancing, in some situations. (See the page in this guide for Slowing the Spread for details on where vaccinated people still need to take precautions.

We are likely to need to keep taking some precautions until young children can be safely vaccinated and until worldwide infection rates are significantly lower.

Available COVID-19 Vaccines

Three vaccines were approved for use in the U.S., from the drug companies Moderna, Pfizer / BioNTech, and Johnson & Johnson. They are very similar: 

  • Are currently approved for adults. At present vaccines from Pfizer / BioNTech and Moderna are approved for people 12+; all three for people 18+.
  • Both the Pfizer/BioNTech and Moderna use mRNA (messenger RNA) to cause our immune systems to build antibodies to the novel coronavirus.
  • The Johnson & Johnson vaccine uses a different technology.

None of these vaccines contain any actual viruses; they cannot cause COVID-19.

First vaccination with the Moderna and Pfizer/BioNTech versions require two doses approximately a month apart (28 days for the Pfizer vaccine, 21 days for Moderna) to be fully effective. The Johnson & Johnson vaccine uses only one dose. Boosters are one single dose.

New bivalent vaccines have been approved for use as a booster only: from Pfizer/BioNTech  for ages 12 and older; and from  Moderna for ages 18 and older. See the section on boosters above for more details.

Proof of Vaccination

Some activities now ask for proof of COVID-19 vaccination to enter or to participate. That could mean showing the card that recorded date(s) and time(s) of vaccination. But it's all too easy to lose that card if it is kept in a wallet or pocket. Instead, it is wiser to keep that card in a safe place, and use one of these alternatives:

  • make a photocopy of both sides, and keep that close to hand in a pocket or wallet or car; or
  • take a photo of both sides with a smartphone; or
  • (for people in California), get a verifiable QR code link to store on a smartphone or other device using the Digital COVID-19 Vaccine Record.

Please don't laminate your vaccine card - it will be needed to record future doses. Be sure that your proof of vaccination is updated when you get a vaccine booster

If you don't have your original vaccination card with you when getting the next dose, check to make sure that your digital vaccination record - see below - has been updated with that information. If it has not, follow the process for a lost vaccination card to correct your information.

What if you've lost your vaccination card? For people in Santa Clara County, here's advice from our county Public Health Department:

Request vaccine verification from the state

visit the vaccination site (if it is still open)

contact the healthcare provider that administered the vaccine

How Do These Vaccines Work? Are They Safe?

Most of us have a really basic idea of how vaccines work: by taking in a small dose of a relatively harmless version of a pathogen, our bodies create antibodies against that disease, so when we're exposed to infection, we are already equipped to fight it off. That's not wrong, but immunity is rather more complex. There are several different types of vaccines; depending on type and depending on the disease, each with their own limitations on how completely they can protect us and for how long.

vaccine safety image, two adults + a child, from the Santa Clara County Department of Public Health.

For a better understanding what vaccines can do for us, see:

How well our bodies resist infection - our immunity, in other words - depends on the strength of the antibodies created in our bodies and on how healthy we are overall. Active immunity (when our bodies create antibodies for ourselves) is stronger than passive immunity (when we are given antibodies from someone else) and also lasts longer.

Vaccine safety is a big concern to many in the U.S. There has been a lot of mis- and dis-information in the last decade on the topic of vaccines, especially vaccines for children. These sources will bust many of those myths:

The Centers for Disease Control and Prevention explains how they will make sure that the COVID-19 vaccines offered to the people of the U.S. are safe:

How Vaccines are Evaluated

With familiar and well-known diseases like whooping cough (pertussis) or polio, we can measure the effectiveness of a vaccine, using past case history and statistics to figure out how many people were not infected because they got the vaccine, compared to unprotected people. 

Effectiveness is impossible to calculate accurately for a new disease like the novel coronavirus. With COVID-19 the best we can do for now is measure efficacy (compare the number of cases in one group that got the vaccine, versus another control group that did not). And as one immunology textbook points out, when we look at vaccines, we are concerned with efficacy in three different areas:

  • Efficacy to prevent infection (also called sterilizing immunity)
  • Efficacy to prevent disease [getting sick and also transmitting the disease to others]
  • Efficacy to prevent severe disease

The currently-available vaccines for COVID-19 are good at the last one, and also the second - but they don't offer sterilizing immunity.

Clinical trials testing efficacy of vaccines need to be as diverse as the population they intend to help. When there's only a small number of people participating in a clinical trial, though, it's hard to have confidence that it will work on more than a narrow slice of the population. The current clinical trials for COVID-19 vaccines being considered in the U.S. are paying attention to that problem; and the National Institutes of Health's All of US program aims to recruit larger and much more diverse groups of people to participate in all kinds of clinical trials, to avoid further bias in healthcare.

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