Questions and Answers About Coronavirus

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3D illustration of coronaviruses, group of viruses that cause diseases in animals and causes respiratory infections in humans
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Since the World Health Organization (WHO) declared the novel coronavirus a pandemic on March 11, 2020, much has been learned about the virus, the disease it causes. Why is this virus so devastating, and how do you know if you're infected? One of the most important things you can do is arm yourself with coronavirus facts, not fear and anecdotal news. Here are answers to common coronavirus questions, including information about COVID-19 vaccines.

What is the coronavirus?

Coronavirus is the name for a large family of viruses. In people, they cause diseases that range from the common cold to SARS (severe acute respiratory syndrome) and MERS (Middle Eastern respiratory syndrome). The coronavirus that emerged in late 2019 is new. Scientists have named it SARS-CoV-2, because it is similar to, but not the same as SARS-CoV. SARS-CoV-2 causes a much milder disease and is far less deadly than SARS-CoV. Scientists have named the SARS-CoV-2 disease outbreak COVID-19, which stands for Coronavirus Disease 2019.

How many cases of COVID-19 are there?

The COVID-19 outbreak began in Wuhan, China in the fall of 2019. The virus spread like wildfire and has reached most of the world. Globally, confirmed cases have surpassed 240 million—including nearly 45 million U.S. cases. Contact your state health department for the latest COVID-19 updates and information about confirmed and suspected cases of infection where you live.

How is the COVID-19 virus transmitted?

SARS-CoV-2 spreads in much the same way as the influenza—or flu—virus. Both the flu and COVID-19 are respiratory illnesses. They spread person to person through droplets from the nose and mouth. You can breathe in these droplets when an infected person coughs, exhales or sneezes around you. The droplets can also land on surfaces. You can become infected if you touch these contaminated surfaces and then touch your eyes, nose or mouth. SARS-CoV-2 exhaled in tiny particles, or aerosols can survive in the air for a few hours, move with air currents, and remain infectious. So, both droplet and airborne transmission are driving the spread of COVID-19, although close contact is the primary driver.

The SARS-CoV-2 strain that started the pandemic spread more efficiently than the flu virus, but not as easily as the measles virus. However, mutations in SARS-CoV-2—which occur naturally as the virus replicates and spreads between people—are making it more contagious. These "variant" viruses are concerning because some of them are spreading 2 to 3 times as fast as the original strain. Someone infected with the latest variant of concern—Delta—can potentially infect 5 to 8 other people, compared to three people with the original strain. People are contagious with or without symptoms.

What are the symptoms of COVID-19?

Coronavirus symptoms are flu-like. They include fever, cough, fatigue and, in some cases shortness of breath. Other symptoms may include loss of sense of smell, headache, and digestive symptoms.

Coronavirus respiratory symptoms begin gradually and are usually mild. Some infected people may not even feel sick or develop symptoms. This makes it different from the flu in which symptoms tend to start suddenly and can be severe. In children, COVID-19 has caused very mild illness more like the common cold. This also differs from the flu, as children are a high-risk flu group. Approximately 20 to 40% of infected people may act as "carriers" of the virus: They do not develop a marked illness but they can still spread it to other people.

Like the flu, some people with COVID-19 become seriously ill and require hospital care. People at risk of more severe illness include people with weakened immune systems and those with chronic conditions, such as heart disease. Like adults, children are at risk of more severe COVID-19 if they have underlying conditions, such as diabetes. Chronic or underlying conditions also increase the risk of COVID-19 complications, such as pneumonia.

How long do COVID-19 symptoms last?

People with mild symptoms (like the common cold) are likely to recover within a week. With more significant symptoms, it may take a couple of weeks to begin to feel better, but possibly six weeks until symptoms resolve completely. It may take longer than six weeks to recover for people with severe illness or complications requiring hospitalization. Approximately 10% of patients experience symptoms several months or longer after infection. The name for this condition is "long COVID," or a post-COVID condition.

How is COVID-19 diagnosed?

Doctors may suspect COVID-19 based on patient symptoms, exposure history, white blood cell counts, and chest imaging exams. The process involves collecting specimens from the patient's nose, mouth, throat or lungs and using a diagnostic kit that can detect genetic material from the virus.

Can you be tested for coronavirus if you don't have symptoms?

Yes. If you had close contact with someone who has COVID-19, get tested and quarantine (stay away from others). Without testing, the guideline is to quarantine 10 to 14 days and monitor yourself daily for symptoms, such as fever. With a negative test result and no symptoms by daily monitoring, you may end quarantine after seven days if necessary. You should still be vigilant about wearing a mask and keeping your distance from others through day 14.

If you're fully vaccinated (it has been two weeks since you completed your vaccination), you don't have to quarantine. But, the vaccines are not 100% effective in preventing infection so it is possible to contract the virus. If you develop symptoms of COVID-19, contact your doctor about testing and stay away from others; inform your doctor of your vaccination status.

How effective is the COVID-19 vaccine?

You can reduce your risk of developing COVID-19 by getting the COVID-19 vaccine. The U.S. Food and Drug Administration (FDA) authorized emergency use for three different COVID-19 vaccines. Two of the vaccines are about 90% effective; another is 76% effective in preventing serious symptoms of COVID-19. Vaccine immunity weakens with time, so people at higher risk of exposure or developing a severe case of COVID-19 may receive a booster shot. While the country works toward greater COVID-19 immunity, standard infection control practices (including social distancing and wearing a face mask in public) help control outbreaks. 

Do the vaccines work against COVID-19 variants?

So far, the COVID-19 vaccines protect against most variants, including the Delta variant, but breakthrough infections are more likely with the Delta variant than the original SARS-CoV-2. Still, fully vaccinated people are well protected from needing hospitalization or dying from COVID-19.

How do doctors treat COVID-19?

In most cases, treatment involves controlling symptoms, such as fever and cough. Severe cases often require hospitalization to prevent and treat complications. There are also some targeted treatments that can help prevent severe disease from developing. The FDA authorized emergency use for certain monoclonal antibodies to treat mild to moderate COVID-19 in people at high risk for severe illness.

A clinical trial evaluating the safety and effectiveness of an antiviral drug, remdesivir (Veklury), led to its approval for people (aged `12 and older) hospitalized with COVID-19. It is not specific for the coronavirus, but it can speed up COVID recovery time in some cases. Based on clinical trial results, doctors may also administer dexamethasone to hospitalized COVID-19 patients; it appears to improve survival.

Blood plasma from patients who recovered from coronavirus is another type of COVID-19 therapy. It also has emergency use authorization, but it may not be as effective against COVID-19 as initially thought.

How dangerous is COVID-19?

Most people have a mild illness and recover with symptom treatment alone. About 15% of people develop a serious illness. This usually happens when people are older or have a chronic medical condition, such as heart or lung disease. With severe cases, there is a risk of complications, such as pneumonia and organ failure. However, people younger than 65 and patients without a known underlying health condition, including children, have also died of COVID-19. Other factors that affect the the risk of dying are access to medical care and socioeconomic status.

Worldwide, about 2% of people confirmed to have COVID-19 have died from it. For some perspective, MERS and SARS both caused very severe respiratory illness in most people who became infected. Up to 40% of people with MERS died and the death rate from SARS was about 10%. The U.S. mortality rate for the 2019-2020 seasonal influenza was 0.06% (22,000 deaths among 38 million flu cases, as estimated from the CDC). There have been 617,211 COVID-19 deaths in the U.S. since the pandemic reached the country in early 2020.

Is air travel safe?

According to the CDC, the risk of infection from the air in a plane is low. This is due to the fact that airplanes filter the air. However, it is difficult to maintain a social distance in airport terminals, security lines, and on a crowded flight. Air travel was considered low risk of infection for fully vaccinated people, until the Delta variant starting spreading. The Delta variant has some ability to escape the immune system, so even if you're vaccinated there is a chance you can contract the virus and spread it to others. Face masks are required for air travel, whether or not you are vaccinated.

Should I avoid international travel?

The U.S. Department of State issues travel advisories. Check the CDC's coronavirus travel page and the U.S. Department of State International Travel page for current information.

Effective January 26, 2021, anyone 2 years and older arriving in the U.S. must show proof of a negative COVID-19 test or COVID-19 recovery (with a doctor's note), including all U.S. citizens, legal permanent residents, and foreign nationals. There may also be mandatory quarantines for upon arrival from certain countries.

Fully vaccinated people do not need to get tested for coronavirus before travel if the destination does not require it. They still need to show proof of a negative coronavirus test before they board and international flight returning to the United States.

How can I protect myself from coronavirus?

Like the flu, protecting yourself from the virus that causes COVID-19 involves vaccination, social distancing, and basic personal hygiene. You can protect yourself and others with these steps:

  • Get the COVID-19 vaccine if you are 12 or older.
  • Avoid touching your eyes, nose and mouth.

  • Cover your nose and mouth with a tissue when you cough or sneeze and dispose of it immediately. If no tissue is available, use the corner of your elbow. Encourage others to do the same.

  • Wear a cloth face mask in any public indoor space and in outdoor spaces when you cannot maintain a social distance of at least 6 feet.

  • Stay at home if you don’t feel well. If you have a fever and cough, call your doctor for an appointment in case it is the flu. If you may have been exposed to someone with confirmed COVID-19, contact your doctor about testing, even if you're vaccinated. 

  • Stay 6 feet or more away from others.

  • Wash your hands regularly and thoroughly for 20 seconds at a time with warm, soapy water. An alcohol-based hand sanitizer will do if soap and water are not available.
  • Avoid crowded, indoor public spaces and those without good ventilation.

Am I at risk if I’ve been around animals?

SARS-CoV-2 made the jump to humans from animals in China. Animals in the United States are not a reservoir of COVID-19 infection. But animals can be a source of other diseases. It is always wise to wash your hands after being around animals, livestock or wildlife.

Are pets and animals at risk of coronavirus?

According to the CDC, there are a small number of reports of pets infected with the virus—in most cases, after being in close contact with people who had COVID-19. There is not enough research to know if animal-to-human spread is playing a significant role in the COVID-19 outbreak. If you have confirmed COVID-19, it may be wise to avoid being around pets or animals until scientists know more about the virus.

For more answers, visit the CDC’s Frequently Asked Questions.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Jun 16
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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