What is COVID-19 and how can I protect myself?
Answer From Daniel C. DeSimone, M.D.
A new virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as the cause of a disease outbreak that began in China in 2019. The disease is called coronavirus disease 2019 (COVID-19).
In March 2020, the World Health Organization (WHO) declared COVID-19 a pandemic. Public health groups, including the U.S. Centers for Disease Control and Prevention (CDC) and WHO, are monitoring the pandemic and posting updates on their websites. These groups have also issued recommendations for preventing the spread of the virus that causes COVID-19.
How does the coronavirus spread?
Data has shown that the COVID-19 virus mainly spreads from person to person among those in close contact. The virus spreads by respiratory droplets released when someone infected with the virus coughs, sneezes, breathes, sings or talks. These droplets can be inhaled or land in the mouth, nose or eyes of a person nearby.
Sometimes the COVID-19 virus can spread when a person is exposed to small droplets or aerosols that stay in the air for several minutes or hours — called airborne transmission.
The virus can also spread if you touch a surface with the virus on it and then touch your mouth, nose or eyes. But the risk is low.
The COVID-19 virus can spread from someone who is infected but has no symptoms. This is called asymptomatic transmission. The COVID-19 virus can also spread from someone who is infected but hasn't developed symptoms yet. This is called presymptomatic transmission.
It's possible to get COVID-19 twice or more.
What are the symptoms of COVID-19?
COVID-19 symptoms can be very mild to severe. Some people have no symptoms. The most common signs and symptoms are fever, cough, tiredness, and loss of taste or smell.
Other signs and symptoms may include shortness of breath, muscle aches, chills, sore throat, headache, chest pain, diarrhea, vomiting and nausea. This list is not complete. Other less common symptoms have also been reported. Symptoms may appear 2 to 14 days after exposure.
Can COVID-19 be prevented?
The U.S. Food and Drug Administration (FDA) has approved or given emergency use authorization to some COVID-19 vaccines. The FDA has approved the Pfizer-BioNTech COVID-19 vaccine, now called Comirnaty, to prevent COVID-19 in people age 12 and older. The FDA has given emergency use authorization to Pfizer-BioNTech COVID-19 vaccines for age 6 months through age 11. The FDA has approved the Moderna vaccine, now called Spikevax, to prevent COVID-19 in people age 18 and older. The FDA has given emergency use authorization to Moderna COVID-19 vaccines for age 6 months to age 17. The FDA has also authorized the Novavax COVID-19, adjuvanted vaccine for people age 12 and older. A vaccine might prevent you from getting COVID-19 or prevent you from becoming seriously ill from COVID-19 if you get the COVID-19 virus.
An additional primary shot of a COVID-19 vaccine is recommended for people who are vaccinated and might not have had a strong enough immune response.
In contrast, a booster dose is recommended for people who are vaccinated and whose immune response weakened over time. Research suggests that getting a booster dose can decrease your risk of infection and severe illness with COVID-19.
What can I do to avoid becoming ill?
There are many steps you can take to reduce your risk of infection from the COVID-19 virus and reduce the risk of spreading it to others. WHO and CDC recommend following these precautions:
- Get vaccinated.
- Avoid close contact with anyone who is sick or has symptoms.
- Keep distance between yourself and others when you're in indoor public spaces.
- Avoid crowds and indoor places that have poor airflow (ventilation).
- Wash your hands often with soap and water for at least 20 seconds. If you're not able to wash your hands, use an alcohol-based hand sanitizer that contains at least 60% alcohol.
- Wear a face mask in indoor public spaces if you're in an area with a high number of people with COVID-19 in the hospital and new COVID-19 cases, whether or not you're vaccinated. The CDC recommends wearing the most protective mask possible that you'll wear regularly, fits well and is comfortable.
- Cover your mouth and nose with your elbow or a tissue when you cough or sneeze. Throw away the used tissue. Wash your hands right away.
- Avoid touching your eyes, nose and mouth.
- Clean and disinfect often-touched surfaces regularly.
If you have a chronic medical condition, you may have a higher risk of serious illness. Check with your health care provider about other ways to protect yourself.
Should I wear a mask?
The CDC recommends masks for the general public. If you're in an area with a high number of people with COVID-19 in the hospital and new COVID-19 cases, the CDC recommends wearing a well-fitted mask indoors in public, whether or not you're vaccinated.
Using masks in public may help reduce the spread from people who don't have symptoms. The CDC says that you should wear the most protective mask possible that you'll wear regularly, fits well and is comfortable. Respirators such as nonsurgical N95s give the most protection. KN95s and medical masks provide the next highest level of protection. Cloth masks provide less protection. The CDC says that surgical N95 masks should be reserved for health care providers.
According to the CDC, if you are vaccinated, you can more safely return to many activities you may not have been able to do because of the pandemic. However, if you are in an area with a high number of people with COVID-19 in the hospital and new COVID-19 cases, the CDC recommends wearing a mask indoors in public. You're considered fully vaccinated two weeks after you get a second dose of an mRNA COVID-19 vaccine, or Novavax COVID-19 vaccine. You are considered fully vaccinated two weeks after you get a single dose of the Janssen/Johnson & Johnson COVID-19 vaccine. You are considered up to date with your vaccines if you have gotten all recommended COVID-19 vaccines, including booster doses, when you become eligible.
The CDC recommends that you wear a mask while on planes, buses, trains and other forms of public transportation.
Can I travel?
If you're planning to travel, check for travel advisories and use appropriate precautions when in public. You may want to talk with your health care provider if you have health conditions that make you more susceptible to respiratory infections and complications.
What can I do if I have or may have COVID-19?
If you develop symptoms or you've been exposed to the virus that causes COVID-19, contact your health care provider for medical advice. Your health care provider will likely recommend that you get tested for COVID-19. If you have emergency COVID-19 symptoms, such as trouble breathing, seek care immediately. If you need to go to a hospital, call ahead so that health care providers can take steps to ensure that others aren't exposed.
Take the following precautions to avoid spreading the virus that causes COVID-19:
- Stay home from work, school and public areas and stay in isolation, except to get medical care.
- Avoid public transportation, taxis and ride-hailing services.
- Wear a cloth face mask around other people or pets.
- Wash your hands frequently with soap and water for at least 20 seconds.
- Isolate yourself as much as possible from other people or pets in your home.
- Use a separate bedroom and bathroom if possible.
- Avoid sharing dishes, glasses, bedding and other household items.
- Clean and disinfect often-touched surfaces daily.
Daniel C. DeSimone, M.D.
Oct. 01, 2022
- Coronavirus disease 2019 (COVID-19). U.S. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-nCoV/index.html. Accessed Oct. 21, 2021.
- Coronavirus disease (COVID-19). World Health Organization. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question-and-answers-hub/q-a-detail/coronavirus-disease-covid-19. Accessed Oct. 21, 2021.
- AskMayoExpert. COVID-19: Inpatient management (adult). Mayo Clinic; 2021.
- Chu DK, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: A systematic review and meta-analysis. Lancet. 2020; doi: 10.1016/S0140-6736(20)31142-9.
- Vaccines and related biological products advisory committee meeting. U.S. Food and Drug Administration. https://www.fda.gov/media/144245/download. Accessed Dec. 9, 2020.
- Emergency use authorization. U.S. Food and Drug Administration. www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization#covid19euas. Accessed Jan. 18, 2022.
- Participate in outdoor and indoor activities. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/outdoor-activities.html. Accessed Oct. 22, 2021.
- Stay up to date with your vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated.html. Accessed Aug. 26, 2022.
- Interim public health recommendations for fully vaccinated people. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html. Accessed Dec. 15, 2021.
- Comirnaty and Pfizer-BioNTech COVID-19 vaccine frequently asked questions. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/comirnaty-and-pfizer-biontech-covid-19-vaccine-frequently-asked-questions. Accessed Aug. 23, 2021.
- Cucinotta D, et al. WHO declares COVID-19 a pandemic. Acta Bio-Medica. 2020; doi:10.23750/abm.v91i1.9397.
- Scientific brief: SARS-CoV-2 transmission. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/sars-cov-2-transmission.html. Accessed Oct. 22, 2021.
- Types of masks and respirators. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/types-of-masks.html. Accessed Jan. 17, 2021.
- Use and care of masks. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/about-face-coverings.html. Accessed Feb. 28, 2022.
- COVID-19 community levels. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/science/community-levels.html. Accessed Feb. 28, 2022.
- Novavax COVID-19 vaccine, adjuvanted. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/novavax-covid-19-vaccine-adjuvanted. Accessed Aug. 26, 2022.
- Science brief: SARS-CoV-2 and Surface (Fomite) Transmission for Indoor community Environments. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/surface-transmission.html. Accessed Aug. 26, 2022.
- Reinfections and COVID-19. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/your-health/reinfection.html. Accessed Aug. 26, 2022.