Frequently Asked Questions

Page Last updated 4/3/2024.

Below are answers to commonly asked questions about COVID-19. Most of the information below comes from the Centers for Disease Control and Prevention (CDC), a trusted and valued source of information.

Please call your healthcare provider for any symptoms that are severe or concerning to you. If you do not have a healthcare provider, call 2-1-1.

Overview and Symptoms

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  • What is COVID-19?

    COVID-19 (coronavirus disease 2019) is a disease caused by a virus named SARS-CoV-2. It can be very contagious and spreads quickly.

    COVID-19 most often causes respiratory symptoms that can feel much like a cold, the flu, or pneumonia. COVID-19 may attack more than your lungs and respiratory system. Other parts of your body may also be affected by the disease. Most people with COVID-19 have mild symptoms, but some people become severely ill.

  • What are the symptoms of COVID-19?

    Not everyone with COVID-19 develops symptoms. Those with COVID-19 may experience a wide range of symptoms - from mild to severe illness.

    Symptoms may appear 2-14 days after exposure to the virus. People with any of the following symptoms may have COVID-19:

    • Fever or chills
    • Cough
    • Shortness of breath or difficulty breathing
    • Fatigue
    • Muscle or body aches
    • Headache
    • New loss of taste or smell
    • Sore throat
    • Congestion or runny nose
    • Nausea or vomiting
    • Diarrhea

    This list does not include all possible symptoms. Symptoms may change with new COVID-19 variants and can vary depending on vaccination status.

    Visit the CDC website for the most up-to-date list of symptoms.

  • How does the COVID-19 virus spread?

    COVID-19 spreads when an infected person breathes out droplets and very small particles that contain the virus. Other people can breathe in these droplets and particles, or these droplets and particles can land on their eyes, nose, or mouth. In some cases, they may contaminate surfaces they touch.

    Anyone infected with COVID-19 can spread it, even if they do NOT have symptoms.

    Visit the CDC website to learn more about how COVID-19 spreads. 

  • What are ways to prevent COVID-19?

    There are many actions you can take to protect you, your household, and your community from COVID-19. 

    In addition to basic health and hygiene practices, like handwashing, the CDC recommends some prevention actions at all COVID-19 hospital admissions levels, which include:


  • Who is at risk of getting very sick from COVID-19?

    Some people are more likely than others to get very sick if they get COVID-19. This includes people who are older, are immunocompromised, have certain disabilities, or have underlying health conditions. Understanding your COVID-19 risk and the risks that might affect others can help you make decisions to protect yourself and others.

  • What are variants of COVID-19?

    Viruses are constantly changing, including the virus that causes COVID-19. These changes occur over time and can lead to new strains of the virus or variants of COVID-19.

    Visit the CDC website to learn more about variants of the virus. 

  • What is COVID-19 reinfection?

    You can become infected with COVID-19, recover, and get infected again (reinfected). Reinfections are most often mild, but severe illness occur. If you are reinfected, you can also spread the virus to others.

    Visit the CDC website for more information on COVID-19 reinfection. 

Testing and Treatment

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  • What should I do if I test positive for COVID-19?
    • Isolate (stay home if you have symptoms, until you have not had a fever for 24 hours without using fever reducing medication AND other symptoms are mild and improving). Visit the County’s If You Are Sick webpage for step-by-step guidance.
    • Take precautions, including wearing a high-quality mask or respirator, to protect others around you from getting infected.
    • Tell people you had recent contact with that they may have been exposed.
    • Monitor your symptoms. If you have any emergency warning signs, seek emergency care immediately.
    • Contact a healthcare provider, community health center, or pharmacy to learn about treatment options that may be available to you. Treatment must be started within the first few days to be effective.

    Visit the CDC website for more information about COVID-19 testing. 

  • What should I do if I'm exposed to someone who tested positive for COVID-19?
    • Anyone with new symptoms of COVID-19 should test right away.
    • People who have been exposed to a confirmed case of COVID-19 and do not have COVID-19 symptoms are only recommended to test if they are at  higher risk of severe disease and would benefit from treatment OR if they have contact with people who are at higher risk for severe COVID-19 infection.  In these situations, they should consider testing within 5 days after the last exposure date (Day 0) and prior to contact with high​​er risk people. 
    • Post-exposure testing is not recommended if a person was infected with COVID-19 in the last 30 days unless they develop new symptoms. If new symptoms consistent with COVID-19 occur and an alternative etiology cannot be identified, antigen testing may be considered. Interpretation of positive test results in such people should be made in consultation with infectious disease or infection control experts.
  • Where can I get tested for COVID-19?

    There are different ways you can test to see if you have COVID-19. Contact your healthcare provider, visit your local drug store, or the County's COVID-19 testing webpage for more information.

    If you do not have a healthcare provider and would like to get connected to one, call 2-1-1. If you have any emergency warning signs, seek emergency care immediately.  

  • How is COVID-19 treated?

    Most people with COVID-19 have mild illness and can recover at home. You can treat symptoms with over-the-counter medicines to help feel better.

    If you have COVID-19 and are more likely to get very sick from COVID-19, treatments are available can reduce your chances of being hospitalized or dying from the disease. Medications to treat COVID-19 must be prescribed by a healthcare provider or pharmacist and started 5-7 days after symptoms appear. Contact a healthcare provider right away to determine if you are eligible for treatment, even if your symptoms are currently mild.

    Visit the CDC website for more information about COVID-19 treatments and medications. 


Getting Your Updated COVID-19 Vaccine(s)

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  • Are COVID-19 vaccines safe?

    Yes. COVID-19 vaccines are safe and effective. Millions of people in the United States (U.S.) have received COVID-19 vaccines under the most intense safety monitoring in U.S. history.

    Visit the CDC website for more information on the safety of COVID-19 vaccines. 

  • What are the ingredients in COVID-19 vaccines?

    Nearly all the ingredients in COVID-19 vaccines are also ingredients in many foods – fats, sugars, and salts.

    None of the COVID-19 vaccines contain ingredients like preservatives, tissues (such as aborted fetal cells), antibiotics, food proteins, medicines, latex, or metals. Exact vaccine ingredients vary by manufacturer.

    Learn more about what ingredients are and are not in Pfizer-BioNTech, Moderna, and Novavax COVID-19 vaccines.

  • What are the risks of getting a COVID-19 vaccine?

    Adults and children may have some side effects from a COVID-19 vaccine, including pain, redness, or swelling at the injection site, tiredness, headache, muscle pain, chills, fever, and nausea. These side effects typically resolve after a few days.

    Serious side effects are rare but may occur. 

  • How were COVID-19 vaccines developed so quickly?

    Although COVID-19 vaccines were developed quickly, research and development on vaccines like these has been underway for decades. All vaccine development steps were taken to ensure COVID-19 vaccine safety and effectiveness, including clinical trials, authorization or approval, and tracking safety using vaccine monitoring systems.

    Visit the CDC website for more information about developing COVID-19 vaccines.

  • Does the CDC show reports of deaths directly linked to the COVID-19 vaccine?

    Anyone can report events to CDC's Vaccine Adverse Event Reporting System (VAERS), even if it is not clear whether a vaccine caused the problem. Because of this, VAERS data alone cannot determine if the reported adverse event was caused by a COVID-19 vaccination.

    Some VAERS reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable. Vaccine safety experts study these adverse events and look for unusually high numbers of health problems, or a pattern of problems, after people receive a particular vaccine.

    The number of deaths reported to VAERS following COVID-19 vaccination has been misinterpreted and misreported as if this number means deaths that were proven to be caused by vaccination. Reports of adverse events to VAERS following vaccination, including deaths, do not necessarily mean that a vaccine caused a health problem.

    Learn more about VAERS.

  • Does the COVID-19 vaccine affect women’s fertility or harm the fetus if pregnant?

    Currently no evidence shows that any vaccines, including COVID-19 vaccines, cause fertility problems (problems trying to get pregnant) in women or men.

    COVID-19 vaccination is recommended for people who are pregnant, trying to get pregnant now, or might become pregnant in the future, as well as their partners.

    Learn more about COVID-19 vaccines and people who would like to have a baby.

  • Do COVID-19 vaccines alter your DNA?

    COVID-19 vaccines do not change or interact with your DNA in any way.

    Both messenger RNA (mRNA) and protein subunit COVID-19 vaccines work by delivering instructions (genetic material) to your cells to start building protection against the virus that causes COVID-19.

    After the body produces an immune response, it gets rid of all the vaccine ingredients just as it would get rid of any information that cells no longer need. This process is a part of normal body functioning.

    The genetic material delivered by mRNA vaccines never enters the nucleus of your cells, which is where your DNA is kept, so the vaccine does not alter your DNA.

    Learn more about how COVID-19 vaccines work.

  • Is this the first-time mRNA has been used in a vaccine?

    mRNA vaccines for the COVID-19 infection are new, but the technology has been used in other vaccines.

    Researchers have been studying and working with mRNA vaccines for decades. This means the process has been standardized and scaled up, making vaccine development faster.

    The mRNA vaccines have been studied before for other infectious diseases like flu, Zika, rabies, and cytomegalovirus (CMV).

    As soon as the necessary information about the virus that causes COVID-19 was available, scientists began designing the mRNA instructions for cells to build the unique spike protein into an mRNA vaccine.

  • Is viral vector vaccine technology brand new and worth the risk?

    Scientists began creating viral vectors in the 1970s and have since been studied rigorously for safety. 

    For decades, hundreds of scientific studies of viral vector vaccines have been conducted and published worldwide. This includes studies based on viral vector vaccines against infectious diseases, such as Ebola and Zika.

    Different types of viral vectors are used in research, including retroviruses, adenoviruses, herpes simplex viruses, and adeno-associated viruses. J&J/Janssen COVID-19 vaccines only use the adenovirus viral vector.

    The viral vector vaccine for COVID-19 is safe and held to the same standards as all other vaccines in the U.S.


  • Do COVID-19 vaccines contain microchips and can they cause you to be magnetic?

    Vaccines work by stimulating your immune system to produce antibodies. After getting vaccinated, you develop immunity to that disease, without having to get the disease first.

    COVID-19 vaccines are not administered to track your movement. They are free from manufactured products such as microelectronics, electrodes, carbon nanotubes, and nanowire semiconductors.

    COVID-19 vaccines are free from metals such as iron, nickel, cobalt, lithium, and rare earth alloys. They do not contain ingredients that can produce an electromagnetic field at the site of your injection.

    Learn more about the ingredients in the COVID-19 vaccinations authorized for use in the United States.

  • Do the COVID-19 vaccines authorized for use in the United States shed or release their components?

    Vaccine shedding is the release or discharge of any of the vaccine components in or outside of the body and can only occur when a vaccine contains a live weakened version of the virus.

    None of the COVID-19 vaccines recommended for use in the U.S. contain a live virus. mRNA and protein subunit vaccines are the two types of currently authorized COVID-19 vaccines available in the U.S.

    Learn more about mRNA and​ protein subunit COVID-19 vaccines.

  • Do doctors know how long it takes the mRNA from the vaccine to break down in your body?

    It takes approximately two weeks for the mRNA to become effective in the body. 

    The mRNA vaccines are stored at extremely low temperatures as they are sensitive to heat.

    Once a person is vaccinated, the vaccine remains only long enough—approximately two weeks—to train the immune system to recognize and fight the COVID-19 virus before disappearing.

    Vaccines train our immune systems to create proteins that fight disease, known as antibodies, just as it would happen when we are exposed to a disease but vaccines work without making us sick.

    Vaccinated people are protected from getting the disease in question and passing on the pathogen, breaking any chains of transmission.

  • Is the COVID-19 vaccine safe for children?

    The COVID-19 vaccine for children as young as 6 months has undergone thorough evaluations by both the U.S. Food and Drug Administration (FDA) and CDC. COVID-19 vaccines have and will continue to undergo the most intensive safety monitoring in U.S. history.

    COVID-19 vaccines are being monitored under the most comprehensive and intense vaccine safety monitoring program in U.S. history. CDC monitors all COVID-19 vaccines after they are authorized or approved for use. CDC and FDA continue to monitor vaccines, keep people informed of findings, and use data to make COVID-19 vaccination recommendations.

    The known risks and possible severe complications of COVID-19 outweigh the potential risks of having a rare, adverse reaction to vaccination.

    The most common side effect  was a sore arm. These side effects may affect your child’s ability to do daily activities, but they should go away in a few days. Many children have no side effects at all, and severe allergic reactions are rare.

    COVID-19 vaccines continue to use several monitoring systems  to track vaccines and ensure their safety.

  • Do COVID-19 vaccines cause new variants?

    New variants of the COVID-19 virus happen because the virus that causes COVID-19 constantly changes through a natural ongoing process of mutation (change).

    COVID-19 vaccines do not create or cause variants of the virus that causes COVID-19. As the COVID-19 virus spreads, it has more opportunities to change.

    Learn more about variants.

Additional FAQs

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  • Are cloth and medical masks dangerous and do they deprive the wearer of oxygen and impede lung function?
    • Regular use of cloth and medical masks when properly worn, does not cause CO2 intoxication nor oxygen deficiency.
    • The CDC states cloth masks and surgical masks do not provide an airtight fit across the face. The Carbon Dioxide (CO2) escapes into the air through the mask when you breathe out or talk. Also, CO2 molecules are small enough to easily pass right through mask material, but the larger size of respiratory droplets carrying the virus will not.
    • The prolonged use of medical masks can be uncomfortable. However, it does not lead to CO2 intoxication nor oxygen deficiency. While wearing a medical mask, make sure it fits properly and that it is tight enough to allow you to breathe normally. Do not re-use a disposable mask and always change it as soon as it gets damp.
    • To ensure a mask is properly ventilated, correctly cleaned or disposed of, and will protect the wearer from COVID-19, visit the CDC’s Your Guide to Masks webpage.

State of Emergency Order

The COVID-19 State of Emergency for California ended on February 28, 2023The Federal COVID-19 Public Health Emergency Declaration ended on May 11, 2023.

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Additional Resources