COVID-19 FAQ: What to Know About Coronavirus, Vaccines, Testing, Masks

Here are answers to frequently asked questions surrounding coronavirus and related restrictions and preventative measures officials are urging.

Which Bay Area Counties Will Follow California's Mask Mandate Lift?

As California prepares to lift the mask mandate on Feb. 16, Bay Area counties have made individual decisions on whether to ditch the face coverings or not.

On Wednesday, Santa Clara County held a press conference to announce its new guidelines. San Francisco Mayor London Breed took to Twitter to say vaccinated people will be able to be maskless in most indoor settings.

Here is a county-by-county breakdown of where the mask mandate stands in your area.

What are the mask rules in California?

A statewide mandate requiring people to wear masks in indoor public settings will remain in place until at least Feb. 15, according to California's Health and Human Services secretary.

What type of mask protects against COVID-19?

Masking is back – well it really never went away in most places. But the COVID-19 omicron variant has sure prompted more mandatory masking.

What should you buy? Consumer Investigator Chris Chmura used mask guidance from CDPH and CDC to help you understand the good, better, and best choices in the video below.

Also, before you buy an N95 mask, look it up to make sure it’s NIOSH approved.

The CDC on Friday, Jan. 14, updated its mask guidance and now says people "may choose" to wear N95 and KN95 masks because they offer the best protection against COVID-19.

NBC Bay Area Consumer Investigator Chris Chmura explains how to select face masks to get the most protection against COVID-19.

What masks should kids be wearing now?

Our NBC Bay Area Responds team reached out to experts to get their take on what masks kids should be wearing to help protect against COVID-19. View the video below for full details on what experts recommend.

The state’s newly-extended indoor mask mandate applies to schools. So, what should your kids wear to class? Consumer Investigator Chris Chmura breaks down what doctors recommend.

Why are so many vaccinated people getting COVID-19 lately?

A couple of factors are at play, starting with the emergence of the highly contagious omicron variant. Omicron is more likely to infect people, even if it doesn't make them very sick, and its surge coincided with the holiday travel season in many places.

Omicron appears to replicate much more efficiently than previous variants. And if infected people have high virus loads, there's a greater likelihood they'll pass it on to others, especially the unvaccinated. Vaccinated people who get the virus are more likely to have mild symptoms, if any, since the shots trigger multiple defenses in your immune system, making it much more difficult for omicron to slip past them all.

How much do boosters protect against infection?

While Moderna and Pfizer's lab trial numbers are very promising, it's unclear how those results will translate to fighting omicron in the real world. But recent studies based on emerging real-world data show that Pfizer's boosters provide roughly 75% protection against symptomatic omicron infection.

In other studies based on real-world data, that number rises to 85% protection against severe disease and hospitalization, according to world-renowned virologist and Columbia University professor Dr. David Ho.

In other words: Even if you test positive, you're far less likely to experience COVID-19 symptoms — particularly those severe enough to hospitalize or kill you — if you're boosted.

"The real protection of the vaccine [booster] is largely against disease, and not against acquisition of infection," Ho says.

Omicron is about twice as contagious as delta, according to models and epidemiologists from the U.K., Ho says. And a recent study Ho conducted on the variant shows that it is "markedly resistant" to the antibodies found in even fully vaccinated people who aren't yet boosted.

"[Omicron] is going to rip right through the population," says Ho. "Those who are vaccinated and boosted are largely going to do OK, even if infected. Those who are vaccinated and not boosted probably will have it slightly worse. But I really fear for those who are not vaccinated."

Which booster should you get, when will protection kick in and how long will it last?

Go with an mRNA vaccine, says Ho. Moderna's booster is a higher dosage than Pfizer's, but the results seem to be "quite similar," he says.

With mRNA vaccines, you'll reach peak protection roughly two or three weeks post-booster. The antibodies you'll gain from the booster will eventually wane over time, and scientists are still working to learn how long your peak protection will last.

Ho, one of the scientists studying that question, says early results show that your booster's protection could wane at a similar rate to your second vaccine dose.

"The waning that's been seen so far [after the original two shot regimen], you would lose half your level by two months, so a half life of two months," he says.

At some point, Ho says, you'll probably need another booster shot — echoing Pfizer CEO Albert Bourla, who told CNBC earlier this month that omicron's spread could accelerate the need for a fourth shot. But, Ho stresses, it's far too early to know what that extra dose's timing will look like.

What are the symptoms of omicron?

COVID-19 has a wide range of symptoms, according to the CDC — and if you're experiencing any of them, you should get tested. Omicron's symptoms may differ slightly, though, more resembling a harsh cold: runny nose, sneezing, sore throat and/or body aches.

Especially given omicron's rampant transmissibility, it's better to be safe than sorry. Even if you think you just have a cold, consider getting a COVID-19 test.

With the omicron variant spreading rapidly, what symptoms should you look for?

Lines at many testing clinics are lengthy right now, and some pharmacies are limiting the number of at-home tests you can buy at a time due to recent surges in demand, so plan accordingly.

If you come into close contact with someone who tests positive, you should also get tested, even if you're vaccinated or boosted, the CDC says. Health experts point out that vaccinated people may not test positive for COVID-19 for at least three days post-exposure, and the CDC says it can take as long as five to seven days.

If you're unsure if you should get tested, the CDC's interactive testing tool can help you find an answer.

How soon might COVID symptoms appear?

According to earlier CDC guidance, COVID symptoms can appear anywhere from two to 14 days after someone is exposed to the virus.

Anyone exhibiting symptoms should get tested for COVID-19.

Some people may never experience symptoms, though they can still spread the virus.

A person is also considered contagious before symptoms appear.

As the omicron variant of COVID-19 spreads rapidly, how soon may symptoms of the virus appear?

How long after COVID exposure could you test positive?

According to the CDC, the incubation period for COVID is between two and 14 days, though the newest guidance from the agency suggests a quarantine of five days for those who are not boosted, but eligible or unvaccinated. Those looking to get tested after exposure should do so five days after the exposure or if they begin experiencing, the CDC recommends.

Those who are boosted and vaccinated, or those who are fully vaccinated and not yet eligible for a booster shot, do not need to quarantine, but should wear masks for 10 days and also get tested five days after the exposure, unless they are experiencing symptoms.

What is the best time to get tested after exposure?

The CDC states that anyone who may have been exposed to someone with COVID should test five days after their exposure, or as soon as symptoms occur.

"If symptoms occur, individuals should immediately quarantine until a negative test confirms symptoms are not attributable to COVID-19," the guidance states.

Where can I get tested for COVID-19?

The demand for COVID-19 testing recently reached “unprecedented” levels in the Bay Area. We've reached out to health officials to help create a local guide for residents looking to get tested. View our county-by-county breakdown on where you can get tested for coronavirus.

Where are those COVID tests the government promised?

The federal website where Americans can request free COVID-19 tests has launched and is accepting orders as the White House looks to address nationwide shortages, but supplies will be limited to just four free tests per home.

The website will provide tests at no cost, including no shipping fee, the White House said.

When are people with COVID most contagious?

The CDC says that its guidelines were updated to reflect growing evidence that suggests transmission of COVID-19 often occurs one to two days before the onset of symptoms and during the two to three days afterward. 

For those without symptoms, CDC guidance states they are considered contagious at least two days before their positive test.

With the rapid spread of the omicron variant of COVID-19, when are people who have contracted the virus most contagious?

What are the latest CDC recommendations for isolation, quarantine?

Health officials in late December cut isolation restrictions for Americans who catch the coronavirus from 10 to five days, and similarly shortened the time that close contacts need to quarantine.

CDC officials said the guidance is in keeping with growing evidence that people with the coronavirus are most infectious in the two days before and three days after symptoms develop.

Here's a breakdown of the CDC's updated recommendations:


The isolation rules are for people who are infected. They are the same for people who are unvaccinated, partly vaccinated, fully vaccinated or boosted.

They say:

  • The clock starts the day you test positive.
  • An infected person should go into isolation for five days, instead of the previously recommended 10.
  • At the end of five days, if you have no symptoms, you can return to normal activities but must wear a mask everywhere — even at home around others — for at least five more days.
  • If you still have symptoms after isolating for five days, stay home until you feel better and then start your five days of wearing a mask at all times.


The quarantine rules are for people who were in close contact with an infected person but not infected themselves.

For quarantine, the clock starts the day someone is alerted they may have been exposed to the virus.

Previously, the CDC said people who were not fully vaccinated and who came in close contact with an infected person should stay home for at least 10 days.

Now the agency is saying only people who got booster shots can skip quarantine if they wear masks in all settings for at least 10 days.

That’s a change. Previously, people who were fully vaccinated — which the CDC has defined as having two doses of the Pfizer or Moderna vaccines, or one dose of the Johnson & Johnson vaccine — could be exempt from quarantine.

Now, people who got their initial shots but not boosters are in the same situation as those who are partly vaccinated or are not vaccinated at all: They can stop quarantine after five days if they wear masks in all settings for five days afterward.

When can you be around people after having COVID?

If you had symptoms, the CDC says you can be around others after you isolate five days and stop exhibiting symptoms. However, you should continue to wear masks for the five days following the end of symptoms to minimize the risk to others.

If you have contracted COVID-19, when can you safely be around people again?

When should you call a doctor?

The CDC urges those who have or may have COVID-19 to watch for emergency warning signs and seek medical care immediately if they experience symptoms including:

  • Trouble breathing
  • Persistent pain or pressure in the chest
  • New confusion
  • Inability to wake or stay awake
  • Pale, gray, or blue-colored skin, lips, or nail beds, depending on skin tone

"This list is not all possible symptoms," the CDC states. "Please call your medical provider for any other symptoms that are severe or concerning to you."

You can also notify the operator that you believe you or someone you are caring for has COVID.

What should I know about kids and the coronavirus?

Dr. Yvonne Maldonado, pediatric COVID-19 expert and physician at Stanford, in the video below discusses the coronavirus surge with kids and young teens.

NBC Bay Area’s Raj Mathai spoke to Dr. Yvonne Maldonado, pediatric COVID expert and physician at Stanford, about the coronavirus surge with kids and young teens.

Are the COVID-19 vaccines safe for children?

Many parents have expressed concern about the speed at which the COVID-19 vaccines were developed and the processes used to monitor their progress.

Some good news, then: The COVID-19 vaccines are subject to the most intensive safety monitoring in U.S. history, says Dr. Lee Savio Beers, president of the American Academy of Pediatrics. And on Oct. 26, the FDA reported that it found zero deaths or "significant adverse events" in Pfizer's early COVID-19 vaccine trials for kids.

"When you track on that process, you realize how many checkpoints there are to really make sure that the data is being looked at very, very, very carefully," Beers says.

As for the mRNA technology behind Pfizer's and Moderna's COVID-19 vaccines, Dr. Ross Kedl, a professor of immunology and microbiology at the University of Colorado School of Medicine, says it's not actually brand new: It's been under development for decades. For many years, the problem was cost — mRNA vaccines were considered too expensive to manufacture and difficult to scale.

  • Get more answers to questions about COVID-19 vaccines for young kids from Beers, Kedl and other health experts here.
Kids who get the COVID vaccine should be able to go maskless in school, says Dr. Alok Patel. "I can't wait to see those kids with their bright, smiling shining faces again," Patel says. He answers all our questions about the COVID vaccines being approved for administration to children.

How are schools reporting coronavirus cases?

Public schools across the Bay Area are providing updates on any coronavirus cases reported on campus through a COVID-19 dashboard. It is part of the California Department of Health's guidance on COVID-19 case reporting by schools.

View our COVID-19 dashboards page for full details.

Any rules surrounding travel?

The state says to follow CDC recommendations and any current California Department of Health travel advisory.

The Associated Press and CNBC contributed to this FAQ.

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