Skip to main content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

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

Trustworthy information about COVID-19

COVID-19 Vaccines - Are We There, Yet?

SARS-CoV-2 is a "novel" coronavirus, meaning it's new to human populations - so it takes time to create, test out and trial, produce, & distribute vaccines for it. This page has links to information about county policies and vaccination locations in the Bay Area, about how vaccines work in general, about the current approaches to creating a SARS-CoV-2 vaccine, and what we know with certainty about vaccine programs in the U.S.. In other words, news you can use to make decisions for yourselves and your loved ones.

If you are interested in going further, a good place to start is MedlinePlus' set of links on COVID-19 vaccines, which includes (among other sources) links to clinical trials, how to enlist in a clinical trial, and links to research articles.

This guide doesn't cover speculative or theoretical research, however. If you wish to keep up to date with vaccine trials worldwide, this is a handy resource:

COVID Vaccination in the Bay Area

For now, distribution of COVID vaccines is according to a statewide plan. For details of that plan, including who is in which phase and tier (along with a lot of other information about COVID vaccines), see:    

Santa Clara County vaccine information








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.

Plans are underway to use stadiums, fairgrounds, and local pharmacies  as vaccination locations once more doses of the vaccines become available.


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.)

Available COVID-19 Vaccines

As of December 18, 2020, two vaccines  have been approved for use in the U.S. from the drug companies Moderna and Pfizer / BioNTech. They are very similar: 

  • Both are approved for adults, but not for children or during pregnancy.
  • Both use mRNA (messenger RNA) to cause our immune systems to build antibodies to the novel coronavirus. Because these vaccines don't include any actual viruses, they cannot cause COVID-19.
  • However mRNA is fragile, so these vaccines must be transported and stored at below-freezing temperatures. The Moderna vaccine can be transported and stored at roughly the same temperatures as frozen foods, but the Pfizer vaccine has to be kept at extremely low temperatures.
  • And to be effective, this vaccine requires two doses, approximately a month apart (28 days for the Pfizer vaccine, 21 days for Moderna.)

For  those last two points, as well as the obvious challenges of getting a new drug into production and out to the public, we should expect there to be some distribution issues at first.

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. It is not expected to provide sterilizing immunity like the smallpox vaccine does; it probably won't keep people from ever being infected. Instead we are likely to need to keep taking some precautions through 2021 (perhaps longer), to continue working to stop the spread.

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.

To know what the vaccines currently in development for SARS-CoV-2 might give us, these resources can give us a better understanding:

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. In the early days of this pandemic there was some hope that passive immunity transferred by blood plasma infusions from people who had recovered from COVID-19 would offer cures, but that turned out to be too unpredictable to be useful on a large scale.

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.

About PlaneTree Health Library

PlaneTree Health Library's mission is to guide the public to trustworthy, accurate, and free health and medical information. In operation since 1989, it is a free, public, patient and consumer health library and  501(c)3 nonprofit organization. It does not take advertisements; recommendations are independent of any commercial relationship.

Visit our online information guides linked from our main website at:

The text on this page is copyright PlaneTree Health Library, licensed under Creative Commons CC BY-SA. Linked contents are the responsibility of their creators / copyright holders.