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

Trustworthy information about COVID-19

Break the Chain of Transmission

What is Social Isolation? Self-Quarantine?

To slow down the spread of coronaviruses, we are asked to "socially distance" ourselves, and to "self-quarantine" if it's possible that we have been in contact with the novel coronavirus. What do these terms mean, exactly? The U.S. Centers for Disease Control gives these definitions in an Interim US Guidance for Risk Assessment on March 7, 2020:

"Distancing means remaining out of congregate settings, avoiding mass gatherings, and maintaining distance (approximately 6 feet or 2 meters) from others when possible."

Congregate settings are crowded public places where close contact with others may occur, such as shopping centers, movie theaters, stadiums.

Isolation means the separation of a person or group of people known or reasonably believed to be infected with a communicable disease and potentially infectious from those who are not infected to prevent spread of the communicable disease. Isolation for public health purposes may be voluntary or compelled by federal, state, or local public health order.

Quarantine in general means the separation of a person or group of people reasonably believed to have been exposed to a communicable disease but not yet symptomatic, from others who have not been so exposed, to prevent the possible spread of the communicable disease.

If I suspect I have been exposed, for how long should I stay isolated?

An analysis of people who were diagnosed with COVID-19 and who had a known time of exposure found that 97% of those cases had an incubation period - the time between exposure and when symptoms appear - of 12 days or fewer. (On average, symptoms showed up around day 5.). Current recommendations for quarantine or isolation for people who suspect they could be infected is 14 days. 

Wear a Face Covering in Public

Wear a face mask or covering whenever you are in public. Face coverings are fairly effective at limiting how far we could spread the virus, and somewhat effective at limiting how much we are exposed to other people's viruses.

risk with & without masks

Infographic from University of Kansas Health System

 Not all masks are equally effective, as this video explains:

There have been several different Orders and recommendations about face coverings since mid-March; to clear the confusion, on June 18 the California Department of Public Health issued an update that requires throughout the state wearing a covering over their mouth and nose when in public settings. Specifically,

Wear a face covering or mask when:

  • inside (or in line to enter) any indoor public space;
  • outdoors in any public space, whenever you cannot keep at least 6 feet away from anyone who does not live in the same household (this includes outdoor activities like hiking, biking, running);
  • waiting for, or using public transportation (including ride sharing, taxis, and tow trucks);
  • at work, if coworkers or members of the public are ever present in the same space.

There are some exemptions, including:

  • children under 2 years old, 
  • while communicating with someone who is deaf or hard of hearing, and 
  • while eating at a restaurant so long as there is at least 6 feet distance from anyone who does not live in the same household.

See the text of the June 18 mandate for more details.

Note: Just wearing a face mask is not enough, not a substitute for other preventive measures. We still need to stay at least 6 feet away from other people, wash hands often, and disinfect surfaces. The CDC warns: "be sure to wash your hands, or use a hand sanitizer, before and after touching your face or face covering. Why? If you are infected you do not want to contaminate your hands. If you are not infected you do not want to inoculate yourself with contaminated hands."

What About Wearing Gloves?

Wearing nitrile gloves may be useful, but the outside surfaces of gloves can spread the coronavirus in the same ways that hands do. They are required in medical settings, and especially when caring for a sick person at home; and also for food preparation or distribution outside the home. Some work settings may also require them.

When you wear gloves, don't touch your face, and take them off carefully and dispose of them responsibly.

Disinfectants and Hand Sanitizers

We've all heard the advice to "wash your hands with soap for 20 seconds". Some even have lists of songs that are at least 20 seconds long to use to in timing how long to wash.

If we cannot wash with soap and water, using hand sanitizer (sometimes called hand scrub) is second-best. Use enough sanitizer that all hand surfaces are cleaned. To be effective against the novel coronavirus, though, the solution should be at least 60% isopropyl or ethanol alcohol ("anti-bacterial" ingredients will not do anything to virus).

 DO NOT USE sanitizer containing methyl alcohol, which is toxic.

The U.S. FDA has found methyl alcohol in over 60 brands of hand sanitizer; for a list of brands of hand sanitizer to avoid, or to read about the science behind this advice, see:

But what about washing surfaces in our homes, schools, or offices? The most effective disinfectants against the novel coronavirus are solutions that use bleach or alcohol. (But remember not to mix bleach with other cleansers!)

disinfectants chart


As an alternative to ready-made disinfectants, these DIY solutions are recommended by reputable sources. (Note: disinfectant solutions intended for flood cleanup are also effective against coronavirus. Ignore the instructions to throw away porous objects, however, and ignore the instructions against mold or mildew.)

If You or Someone in your Household has - or is Suspected to Have - a COVID-19 Infection

Until the time that coronavirus test kits are more widely available, it's recommended that people who have symptoms that fit the profile of COVID-19 disease

a) communicate with a doctor ASAP, if possible, to assess the severity of their symptoms; 

b) self-quarantine for at least 14 days, and

c) clean and disinfect key areas of their home.

People who are at risk for severe disease if they should be infected are also advised to self-quarantine, cleaning and/or disinfecting daily. The people who live with them, or are in close contact with them, should practice isolation as well.

Longer-Term Strategies for Reopening California

Isolation, quarantine, sheltering at home, and distancing restrictions are intended to slow the spread of the coronavirus to  avoid overwhelming local healthcare providers until such time as a reliable vaccine against COVID-19 is widely available These avoidance restrictions are important, but they won't cure this disease.

Historical data, including the worldwide influenza epidemic of 100 years ago, shows us that's what is likely to happen if restrictions are released all at once, all over the country. That's why coordination between state, regional, and local health authorities is so important.  Conditions at the county level are what decides which stage and how many businesses need to be closed. This is to lower the chance that infectious local hot spots would cause a spike in new infections. 

California state government created stages for re-opening in the Resilience Roadmap, revised in late August as the Blueprint.  Various metrics - the number of new cases, the number of people tested, the numbers of people hospitalized and the numbers of deaths - are used to measure if and  when a county could move to the next step in the re-opening process. And to decide when counties need to lock back down again. The state monitors each county's performance on those key criteria, and a county cannot open further (move up to the next stage) until its metrics meet those requirements.

For more information on testing for COVID-19 in the Bay Area and on contact tracing, please see the box for Screening & Testing on the page in this guide for What to Do If... .

 What about vaccines?

Until the time that proven vaccines are available to the people of Santa Clara County, information about vaccine research is too speculative for our webpages. However, if you wish to stay up to date with vaccine trials worldwide, this vaccine research tracker will be useful:

Advice on Travel

COVID-19 is pandemic; people are infected all over the world. Travel was - and is - the main way this disease is spread from community to community, from my town to your town, from country to county. 

While public transit is a necessity in the traffic-congested Bay Area, there's also concern about possible spread of the novel coronavirus on buses and trains. Routes may be changed during the pandemic, and policies may change - check the websites relevant for you frequently.

  Considering air travel, or need to change tickets? Check these links:

To slow the spread of the novel coronavirus in the United States, the Centers for Disease Control publishes updates, recommendations for travelers, and news about travel restrictions. Besides considering the risks of traveling to and from your destination, also investigate what's done at  your lodging to limit exposure (ask about hotel or B&B cleaning practices) and calculate the risks of the kinds of activities you plan to include on the trip.

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