Older couple sitting on the couch together and reading a newspaper
Older couple sitting on the couch together and reading a newspaper
Older couple sitting on the couch together and reading a newspaper

Coronavirus (COVID-19): Frequently Asked Questions

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As the coronavirus pandemic continues, Lisa Maragakis, M.D., M.P.H., senior director of infection prevention at Johns Hopkins, answers some questions circulating among the public and shares current medical and scientific knowledge.

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Protecting Yourself from the Coronavirus

Should I get a COVID-19 vaccine?

Yes. Three COVID-19 vaccines have been authorized for emergency use among specific age groups by the U.S. Food and Drug Administration (FDA), and now the Pfizer vaccine has received full FDA approval. Johns Hopkins Medicine views all authorized and approved COVID-19 vaccines as highly effective at preventing serious disease, hospitalization and death from COVID-19. 

Learn more about coronavirus vaccine safety and what you need to know about the COVID vaccines.

What is the delta variant?

Since the beginning of the COVID-19 pandemic, SARS-CoV-2, the coronavirus that causes COVID-19, has mutated (changed), resulting in different variants. One of these is called the delta variant. Delta is regarded as one of the most contagious forms of the coronavirus so far, and currently accounts for the majority of COVID-19 cases in the U.S.

Traveling internationally if you are not fully vaccinated against COVID-19 is not recommended, because it puts you at risk for infection with the delta variant. This includes unvaccinated children.

Being fully vaccinated against COVID-19 can protect you from the delta variant. All three FDA-authorized or FDA-approved COVID-19 vaccines can protect you from the most severe effects of the delta variant. While COVID-19 vaccines are not perfect, and fully vaccinated people can still catch and transmit the virus, they are highly effective against serious coronavirus disease and greatly decrease the likelihood of hospitalization and death from COVID-19.

Should I wear a face mask?

The CDC continues to monitor the spread of COVID-19 and recommends wearing face masks — for those who are fully vaccinated as well as those who are not — especially when you are in areas of high viral transmission.

The CDC recommends wearing masks and maintaining physical distancing in doctors’ offices, hospitals or long-term-care facilities. Johns Hopkins Medicine’s current safety guidelines require everyone to wear masks inside our facilities, including hospitals, care centers and offices.

Learn more about protecting yourself from coronavirus.

Can I make my own hand sanitizer?

There are no studies supporting the effectiveness of homemade hand sanitizer in killing the coronavirus on people’s hands. Experts agree that the best method for cleaning hands is washing for at least 20 seconds with soap and water.

Can you catch the coronavirus from surfaces?

Although the coronavirus weakens and dies over time outside the human body, studies suggest it can live on surfaces for a few hours or up to several days, depending on the surface, temperature and other environmental factors. For instance, a small amount of the coronavirus is detectable on plastic surfaces for up to three days, on stainless steel for up to two days and up to one day on cardboard, but it’s at less than 0.1% of the starting virus material.

So far, evidence suggests that the virus does not survive as well on a soft surface (such as fabric) as it does on frequently touched hard surfaces like elevator buttons and door handles.

More research will provide information on the coronavirus and how long it lives on surfaces. In the meantime, wash your hands thoroughly after being in public places.

Learn more: Coronavirus Disease 2019: Myth vs. Fact

Is it safe to go shopping?

It’s safer to wear a mask when you are in the store, avoid unnecessary trips and maintain physical distancing as you shop. Be sure to clean your hands often while shopping and as soon as you get home.

Can I go to the gym?

If the coronavirus is spreading in your community, working out at home is safer than going to an indoor fitness center. If you go to the gym, wear a mask and avoid high intensity group classes that take place indoors. Items touched by many people (such as handles and barbells) could pose a risk. In order to practice physical distancing during an increase in COVID-19 cases, it is best to avoid crowded public places when possible.

Is it safe to travel?

Outbreaks of coronavirus variants, including the very contagious delta variant, are occurring in the United States and in countries around the world. Traveling to places with high infection rates, especially with unvaccinated children or adults, raises the risk of catching and transmitting the virus. The Centers for Disease Control and Prevention (CDC) has updated travel information on a range of destinations.

Travelers should be cautious about cruise ship travel and situations that involve crowded places. You are less likely to catch the coronavirus that causes COVID-19 on airplanes because of air circulation and filtering, but you may be asked about your infection risk when you book a flight. And be aware that you may be prevented from returning from certain sites should they be on lockdown due to a surge in cases.

The COVID-19 Vaccines: What you need to know | Las vacunas anticovid-19: información imprescindible

Can humans get the coronavirus from dogs or cats?

Jason Villano, D.V.M., a veterinary expert at Johns Hopkins, says, “Despite the very few reports worldwide, including here in the United States, of sick and healthy domestic animals, including pets, testing positive for SARS-CoV-2, the virus that causes COVID-19, there is little evidence at this time that such animals are easily infected with the virus under normal conditions, or could transmit it.”

If COVID-19 cases are increasing in your area, experts recommend keeping pets indoors or avoiding socialization of pets with other animals, and maintaining good hygiene when handling or caring for your animals.

  • Wash your hands before and after interacting with animals.
  • Don’t kiss your pets or let them lick you or share your food.
  • Walk dogs on a leash. Do not allow pets to interact with people or other animals outside the household.
  • People who are ill with COVID-19 should let someone else take care of their animals. If this isn’t possible, patients should wear a mask while looking after their pet, and wash their hands before and after.

Reliable sources for updates include the CDC, the United States Department of Agriculture and the American Veterinary Medical Association.

What are COVID-19 symptoms?

COVID-19 symptoms include:

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

Symptoms and risk factors may vary in different people. If you have concerns, especially if you think you might have been exposed to the coronavirus that causes COVID-19, call your doctor. Learn more about COVID-19 symptoms.

Coronavirus: What do I do if I Feel Sick?

If you are concerned that you may have COVID-19, follow these steps to help protect your health and the health of others.

Understanding the Coronavirus and COVID-19

What is the COVID fatality rate?

COVID-19 causes more cases of severe disease and more deaths than the seasonal flu. People over age 85 have the highest risk of fatality and children under 19 have the lowest, but this could change as more people are tested and trends become clearer for the variants. If, over time, widespread testing reveals milder, nonfatal cases of COVID-19, the death rate will go down.

See more about coronavirus by the numbers.

Can the coronavirus live in heat? Do COVID-19 cases decline when it gets warm outside?

While some viral illnesses, like the flu, seem to be less common in warmer months, it is still possible to catch them during that time. Researchers are exploring the effects of temperature, ventilation and weather on the spread of the coronavirus. Regardless of the season, people gathering indoors can spread the coronavirus.

Why is it called a ‘coronavirus’?

Corona means “crown,” and coronaviruses have a “crown” of protruding points on their surface that gives them a characteristic appearance when seen under a microscope. Coronaviruses are a whole family of viruses; there are many.

What’s the difference between the new coronavirus and other coronaviruses?

There are many different kinds of coronavirus. Some only affect animals. Some have been circulating among human beings for years, causing respiratory illness and colds. Others have caused small, severe human disease outbreaks in the past, such as the coronaviruses that caused severe acute respiratory syndrome (SARS) in 2003 and Middle East respiratory syndrome (MERS) in 2012. The new coronavirus is different from these, and was first identified in December 2019.

Learn more about COVID-19.

Is Coronavirus Airborne?

Our infection prevention expert provides a brief overview of what we should know about how the coronavirus spreads.

Is the coronavirus airborne?

Yes, the coronavirus can be transmitted through the air by tiny respiratory particles that contain the virus. These infectious particles are dispersed into the air when a person carrying the coronavirus breathes, talks, sings, coughs or sneezes. The CDC has updated its information on airborne spread of the coronavirus.

Respiratory droplets range in size, but in general they are considered large or small. Large respiratory droplets may be visible, and they fall to the ground relatively close to the person who exhaled them — usually seconds to a minute after they are exhaled. Smaller respiratory droplets, however, may remain suspended in the air for minutes to hours, and they may travel far from the person who exhaled them.

The fact that the coronavirus can be contagious through the air is why it is so important to wear a mask when you are around other people, even after you have been fully vaccinated. Masks prevent respiratory droplets from spreading, not only when you cough and sneeze, but also when you are talking, singing or exercising.

In addition to wearing a face mask, maintaining physical distancing (of at least 6 feet), hand-washing, and cleaning and disinfecting surfaces are important ways to prevent virus transmission. When the coronavirus is spreading throughout your community, staying away from poorly ventilated indoor areas and crowded indoor gatherings are critical ways to avoid encountering a concentration of suspended small droplets and particles carrying the virus.

Rarely, the virus may be spread by touching high-touch surfaces like light switches, doorknobs or handrails and then touching your face, mouth or eyes. Make sure to disinfect high-touch surfaces frequently, and wash your hands or use hand sanitizer often.

Scientist carefully insets a pipette into a test tube.

Coronavirus (COVID-19)

What you need to know from Johns Hopkins Medicine.

Updated August 30, 2021