As coronavirus spreads, many questions and some answers

The rapid spread of the virus that causes COVID-19 has sparked alarm worldwide. The World Health Organization (WHO) has declared this rapidly spreading coronavirus outbreak a pandemic, and many countries are grappling with a rise in confirmed cases. In the US, the Centers for Disease Control and Prevention (CDC) is advising people to be prepared for disruptions to daily life that will be necessary if the coronavirus spreads within communities.

Below, you’ll find answers to a number of questions about coronavirus and COVID-19. We will be adding new questions and updating answers as reliable information becomes available.

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FAQs about Coronavirus and COVID-19

What is coronavirus? What is COVID-19?
What are the symptoms of COVID-19?
What can I do to prevent myself and others from getting coronavirus?
How can I prepare myself and family for possible quarantine or isolation?
What should I do if I feel sick?
If a loved one gets sick, how can I care for them?
What do phrases like “community spread” and “social distancing” mean?
Questions about coronavirus or COVID-19? Click here.

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More about COVID-19 and how to protect yourself

• Be careful where you get your news about coronavirus
• Coronavirus: What parents should know and do
• How to talk to children about the coronavirus
• How to talk to teens about the new coronavirus
• Coping with coronavirus anxiety
• Pregnant and worried about the new coronavirus?

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What is coronavirus?

Coronaviruses are an extremely common cause of colds and other upper respiratory infections.

What is COVID-19?

COVID-19, short for “coronavirus disease 2019,” is the official name given by the World Health Organization to the disease caused by this newly identified coronavirus.

How many people have COVID-19?

The numbers are changing rapidly.

The most up-to-date information is available from the World Health Organization, the US Centers for Disease Control and Prevention, and Johns Hopkins University.

It has spread so rapidly and to so many countries that the World Health Organization has declared it a pandemic (a term indicating that it has affected a large population, region, country, or continent).

The flu kills more people than COVID-19, at least so far. Why are we so worried about COVID-19? Shouldn’t we be more focused on preventing deaths from the flu?

You’re right to be concerned about the flu. Fortunately, the same measures that help prevent the spread of the COVID-19 virus — frequent and thorough handwashing, not touching your face, coughing and sneezing into a tissue or your elbow, avoiding people who are sick, and staying away from people if you’re sick — also help to protect against spread of the flu.

If you do get sick with the flu, your doctor can prescribe an antiviral drug that can reduce the severity of your illness and shorten its duration. There are currently no antiviral drugs available to treat COVID-19.

Should I get a flu shot?

While the flu shot won’t protect you from developing COVID-19, it’s still a good idea. Most people older than six months can and should get the flu vaccine. Doing so reduces the chances of getting seasonal flu. Even if the vaccine doesn’t prevent you from getting the flu, it can decrease the chance of severe symptoms. But again, the flu vaccine will not protect you against this coronavirus.

Why is it so difficult to develop treatments for viral illnesses?

An antiviral drug must be able to target the specific part of a virus’s life cycle that is necessary for it to reproduce. In addition, an antiviral drug must be able to kill a virus without killing the human cell it occupies. And viruses are highly adaptive. Because they reproduce so rapidly, they have plenty of opportunity to mutate (change their genetic information) with each new generation, developing resistance to whatever drugs or vaccines we develop.

What are the symptoms of COVID-19?

Some people infected with the virus have no symptoms. When the virus does cause symptoms, common ones include low-grade fever, body aches, coughing, nasal congestion, runny nose, and sore throat. However, COVID-19 can occasionally cause more severe symptoms like high fever, severe cough, and shortness of breath, which often indicates pneumonia.

How long is it between when a person is exposed to the virus and when they start showing symptoms?

Because this coronavirus has just been discovered, the time from exposure to symptom onset (known as the incubation period) for most people has yet to be determined. Based on current information, symptoms could appear as soon as three days after exposure to as long as 13 days later. Recently published research found that on average, the incubation period is about five days.

How does coronavirus spread?

The coronavirus is thought to spread mainly from person to person. This can happen between people who are in close contact with one another. Droplets that are produced when an infected person coughs or sneezes may land in the mouths or noses of people who are nearby, or possibly be inhaled into their lungs.

Coronavirus can also spread from contact with infected surfaces or objects. For example, a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes.

How deadly is COVID-19?

The answer depends on whether you’re looking at the fatality rate (the risk of death among those who are infected) or the total number of deaths. So far, influenza has caused far more deaths this flu season, both in the US and worldwide, than COVID-19. This is why you may have heard it said that the flu is a bigger threat.

Regarding the fatality rate, it appears that the risk of death with the pandemic coronavirus infection (commonly estimated at 3% to 4%) is less than it was for SARS (approximately 11%) and MERS (about 35%), but may be higher than the risk from seasonal flu (which averages about 0.1%).

However, the numbers circulating right now for this new coronavirus are likely to be adjusted over time, as more people are tested and reporting becomes more consistent. For example, testing has been limited at the start of the outbreak, which could result in fewer identified cases, making it seem as though a larger percentage of infections are fatal. In fact, some recent estimates put the mortality rate of the new coronavirus closer to 1%.

Who is at highest risk for getting very sick from COVID-19?

Older people, especially those with underlying medical problems like chronic bronchitis, emphysema, heart failure, or diabetes, are more likely to develop serious illness.

In addition, several underlying medical conditions may increase the risk of serious COVID-19 for individuals of any age. These include:

• blood disorders, such as sickle cell disease, or taking blood thinners
• chronic kidney disease
• chronic liver disease, including cirrhosis and chronic hepatitis
• any condition or treatment that weakens the immune response (cancer, cancer treatment, organ or bone marrow transplant, immunosuppressant medications, HIV or AIDS)
• current or recent pregnancy in the last two weeks
• diabetes
• inherited metabolic disorders and mitochondrial disorders
• heart disease, including coronary artery disease, congenital heart disease, and heart failure
• lung disease, including asthma, COPD (chronic bronchitis or emphysema)
• neurological and neurologic and neurodevelopment conditions such as cerebral palsy, epilepsy (seizure disorders), stroke, intellectual disability, moderate to severe developmental delay, muscular dystrophy, or spinal cord injury.

Are kids immune to the virus that causes COVID-19?

Children, including very young children, can develop COVID-19. However, children tend to experience milder symptoms such as fever, runny nose, and cough. Some children have had severe complications, but this has been less common. Children with underlying health conditions may be at increased risk for severe illness.

Will warm weather stop the outbreak of COVID-19?

Some viruses, like the common cold and flu, spread more when the weather is colder. But it is still possible to become sick with these viruses during warmer months. At this time, we do not know whether the spread of COVID-19 will decrease when the weather warms up.

Should I accept packages from China?

There is no reason to suspect that packages from China harbor coronavirus. Remember, this is a respiratory virus similar to the flu. We don’t stop receiving packages from China during their flu season. We should follow that same logic for the virus that causes COVID-19.

Can I catch the coronavirus by eating food handled or prepared by others?

We are still learning about transmission of the new coronavirus. It’s not clear if it can be spread by an infected person through food they have handled or prepared, but if so it would more likely be the exception than the rule.

That said, the new coronavirus is a respiratory virus known to spread by upper respiratory secretions, including airborne droplets after coughing or sneezing. The virus that causes COVID-19 has also been detected in the stool of certain people. So we currently cannot rule out the possibility of the infection being transmitted through food by an infected person who has not thoroughly washed their hands. In the case of hot food, the virus would likely be killed by cooking. This may not be the case with uncooked foods like salads or sandwiches.

What can I do to protect myself and others from COVID-19?

The following actions help prevent the spread of COVID-19, as well as other coronaviruses and influenza:

• Avoid close contact with people who are sick.
• Avoid touching your eyes, nose, and mouth.
• Stay home when you are sick.
• Cover your cough or sneeze with a tissue, then throw the tissue in the trash.
• Clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe.
• Wash your hands often with soap and water.

This chart illustrates how protective measures such as limiting travel, avoiding crowds, social distancing, and thorough and frequent handwashing can slow down the development of new COVID-19 cases and reduce the risk of overwhelming the health care system.

What do I need to know about washing my hands effectively?

Wash your hands often with soap and water for at least 20 seconds, especially after going to the bathroom; before eating; and after blowing your nose, coughing, or sneezing.

• If soap and water are not readily available, use an alcohol-based hand sanitizer with at least 60% alcohol, covering all surfaces of your hands and rubbing them together until they feel dry.
• Always wash hands with soap and water if hands are visibly dirty.
• The CDC’s handwashing website has detailed instructions and a video about effective handwashing procedures.

Should I wear a face mask?

Follow public health recommendations where you live. As of February 26, 2020, face masks are not recommended for the general public in the US. Some health facilities require people to wear a mask under certain circumstances.

If you have respiratory symptoms like coughing or sneezing, experts recommend wearing a mask to protect others. This may help contain droplets containing any type of virus, including the flu, and protect anyone within three to six feet of the infected person.

The CDC offers more information about masks. The WHO offers videos and illustrations on when and how to use a mask.

Is it safe to travel by airplane?

Stay current on travel advisories from regulatory agencies. This is a rapidly changing situation.

Anyone who has a fever and respiratory symptoms should not fly if at all possible. Even if a person has symptoms that feel like just a cold, he or she should wear a mask on an airplane.

Is there a vaccine available?

No vaccine is available, although scientists will be starting human testing on a vaccine very soon. However, it may be a year or more before we even know if we have a vaccine that works.

Can a person who has had coronavirus get infected again?

While we don’t know the answer yet, most people would likely develop at least short-term immunity to the specific coronavirus that causes COVID-19. However, you would still be susceptible to a different coronavirus infection. Or, this particular virus could mutate, just like the influenza virus does each year. Often these mutations change the virus enough to make you susceptible, because your immune system thinks it is an infection that it has never seen before.

I’m taking a medication that suppresses my immune system. Should I stop taking it so I have less chance of getting sick from the coronavirus?

If you contract the virus, your response to it will depend on many factors, only one of which is taking medication that suppresses your immune system. In addition, stopping the medication on your own could cause your underlying condition to get worse. Most importantly, don’t make this decision on your own. It’s always best not to adjust the dose or stop taking a prescription medication without first talking to the doctor who prescribed the medication.

Will a pneumococcal vaccine help protect me against coronavirus?

Vaccines against pneumonia, such as pneumococcal vaccine and Haemophilus influenza type B (Hib) vaccine, only help protect people from these specific bacterial infections. They do not protect against any coronavirus pneumonia, including pneumonia that may be part of COVID-19. However, even though these vaccines do not specifically protect against the coronavirus that causes COVID-19, they are highly recommended to protect against other respiratory illnesses.

I’m older and have a chronic medical condition, which puts me at higher risk for getting seriously ill, or even dying from COVID-19. What can I do to reduce my risk of exposure to the virus?

Anyone 60 years or older is considered to be at higher risk for getting very sick from COVID-19. This is true whether or not you also have an underlying medical condition, although the sickest individuals and most of the deaths have been among people who were both older and had chronic medical conditions, such as heart disease, lung problems or diabetes.

The CDC suggests the following measures for those who are at higher risk:

• Obtain several weeks of medications and supplies in case you need to stay home for prolonged periods of time.
• Take everyday precautions to keep space between yourself and others.
• When you go out in public, keep away from others who are sick, limit close contact, and wash your hands often.
• Avoid crowds.
• Avoid cruise travel and nonessential air travel.
• During a COVID-19 outbreak in your community, stay home as much as possible to further reduce your risk of being exposed.

Can my pet infect me with the virus that causes COVID-19?

At present, there is no evidence that pets such as dogs or cats can spread the COVID-19 virus to humans. However, pets can spread other infections that cause illness, including E. coli and Salmonella, so wash your hands thoroughly with soap and water after interacting with pets.

What can I do to keep my immune system strong?

Your immune system is your body’s defense system. When a harmful invader — like a cold or flu virus, or the coronavirus that causes COVID-19 — gets into your body, your immune system mounts an attack. Known as an immune response, this attack is a sequence of events that involves various cells and unfolds over time.

Following general health guidelines is the best step you can take toward keeping your immune system strong and healthy. Every part of your body, including your immune system, functions better when protected from environmental assaults and bolstered by healthy-living strategies such as these:

• Don’t smoke.
• Eat a diet high in fruits, vegetables, and whole grains.
• Take a multivitamin if you suspect that you may not be getting all the nutrients you need through your diet.
• Exercise regularly.
• Maintain a healthy weight.
• Control your stress level.
• Control your blood pressure.
• If you drink alcohol, drink only in moderation (no more than one to two drinks a day for men, no more than one a day for women).
• Get enough sleep.
• Take steps to avoid infection, such as washing your hands frequently and trying not to touch your hands to your face, since harmful germs can enter through your eyes, nose, and mouth.

What types of medications and health supplies should I have on hand for an extended stay at home?

Try to stock at least a 30-day supply of any needed prescriptions. If your insurance permits 90-day refills, that’s even better. Make sure you also have over-the-counter medications and other health supplies on hand.

Medical and health supplies

• prescription medications
• prescribed medical supplies such as glucose and blood-pressure monitoring equipment
• fever and pain medicine, such as acetaminophen or ibuprofen
• cough and cold medicines
• antidiarrheal medication
• thermometer
• fluids with electrolytes
• soap and alcohol-based hand sanitizer
• tissues, toilet paper, disposable diapers, tampons, sanitary napkins
• garbage bags

Should I keep extra food at home? What kind?

Consider keeping a two-week to 30-day supply of nonperishable food at home. These items can also come in handy in other types of emergencies, such as power outages or snowstorms.

• canned meats, fruits, vegetables, and soups
• frozen fruits, vegetables, and meat
• protein or fruit bars
• dry cereal, oatmeal, or granola
• peanut butter or nuts
• pasta, bread, rice, and other grains
• canned beans
• chicken broth, canned tomatoes, jarred pasta sauce
• oil for cooking
• flour, sugar
• crackers
• coffee, tea, shelf-stable milk, canned juices
• bottled water
• canned or jarred baby food and formula
• pet food
• household supplies like laundry detergent, dish soap, and household cleaner.

What should I do if I think I or my child may have a COVID-19 infection?

First call your doctor or pediatrician for advice.

If you do not have a doctor and you are concerned that you or your child may have COVID-19, contact your local board of health. They can direct you to the best place for evaluation and treatment in your area.

It’s best to not seek medical care in an emergency department unless you have symptoms of severe illness. Severe symptoms include high or very low body temperature, shortness of breath, confusion, or feeling you might pass out. Call the emergency department ahead of time to let the staff know that you are coming, so they can be prepared for your arrival.

How do I know if I have COVID-19 or the regular flu?

COVID-19 often causes symptoms similar to those a person with a bad cold or the flu would experience. And like the flu, the symptoms can progress and become life-threatening. Your doctor is more likely to suspect coronavirus if:

• you have respiratory symptoms

and

• you recently traveled to countries with ongoing community spread of the COVID-19 virus, including China, Iran, Italy, Japan, South Korea, or
• you have been exposed to someone suspected of having COVID-19, or
• there has been community spread of the virus that causes COVID-19 in your area

How is someone tested for COVID-19?

A specialized test must be done to confirm that a person has been infected with the virus that causes COVID-19. Most testing in the US has been performed at the CDC. The CDC has now approved states to do testing. While this means that a wider group of people will be tested, testing is still limited and still requires a doctor’s order.

How soon after I’m infected with the new coronavirus will I start to be contagious?

The time from exposure to symptom onset (known as the incubation period) is thought to be 14 days, though symptoms typically appear within four or five days after exposure. We don’t know the extent to which people who are not yet experiencing symptoms can infect others, but it’s possible that people may be contagious for several days before they become symptomatic.

For how long after I am infected will I continue to be contagious? At what point in my illness will I be most contagious?

People are thought to be most contagious early in the course of their illness, when they are beginning to experience symptoms. Researchers have detected viral genetic material in patients several weeks after they’ve recovered from COVID-19. Though the significance of these findings is not fully understood, it suggests the possibility that people may continue to be contagious for weeks after they are feeling better.

If I get sick with COVID-19, how long until I will feel better?

It depends on how sick you get. Those with mild cases appear to recover within one to two weeks. With severe cases, recovery can take six weeks or more. According to the most recent estimates, about 1% of infected persons will succumb to the disease.

How long after I start to feel better will be it be safe for me to go back out in public again?

We don’t know for certain. Based on research that has detected viral genetic material in patients several weeks after they’ve recovered from COVID-19, it is safest to assume that you may be contagious for weeks after you recover.

What’s the difference between self-isolation and self-quarantine, and who should consider them?

Self-isolation is voluntary isolation at home by those who have or are likely to have COVID-19 and are experiencing mild symptoms of the disease (in contrast to those who are severely ill and may be isolated in a hospital). The purpose of self-isolation is to prevent spread of infection from an infected person to others who are not infected. If possible, the decision to isolate should be based on physician recommendation. If you have tested positive for COVID-19, you should self-isolate.

You should strongly consider self-isolation if you:

• have been tested for COVID-19 and are awaiting test results
• have been exposed to the new coronavirus and are experiencing symptoms consistent with COVID-19 (fever, cough, difficulty breathing), whether or not you have been tested.

You may also consider self-isolation if you have symptoms consistent with COVID-19 (fever, cough, difficulty breathing) but have not had known exposure to the new coronavirus and have not been tested for the virus that causes COVID-19. In this case, it may be reasonable to isolate yourself until your symptoms fully resolve, or until you are able to be tested for COVID-19 and your test comes back negative.

Self-quarantine is voluntary quarantine at home by those who may have been exposed to the COVID-19 virus but are not experiencing symptoms associated with COVID-19 (fever, cough, difficulty breathing). The purpose of self-quarantine (as with self-isolation) is to prevent the possible spread of COVID-19. We are still awaiting consistent public health guidance on the question of who should self-quarantine. When possible, the decision to quarantine should be based on physician recommendation. Self-quarantine is reasonable if you are not experiencing symptoms, but have been exposed to the COVID-19 virus.

What does it really mean to self-isolate or self-quarantine? What should or shouldn’t I do?

If you are sick with COVID-19 or think you may be infected with the COVID-19 virus, it is important not to spread the infection to others while you recover. While home-isolation or home-quarantine may sound like a staycation, you should be prepared for a long period during which you might feel disconnected from others and anxious about your health and the health of your loved ones. Staying in touch with others by phone or online can be helpful to maintain social connections, ask for help, and update others on your condition.

Here’s what the CDC recommends to minimize the risk of spreading the infection to others in your home and community.

Stay home except to get medical care

• Do not go to work, school, or public areas.
• Avoid using public transportation, ride-sharing, or taxis.

Call ahead before visiting your doctor

• Call your doctor and tell them that you have or may have COVID-19. This will help the healthcare provider’s office to take steps to keep other people from getting infected or exposed.

Separate yourself from other people and animals in your home

• As much as possible, stay in a specific room and away from other people in your home. Use a separate bathroom, if available.
• Restrict contact with pets and other animals while you are sick with COVID-19, just like you would around other people. When possible, have another member of your household care for your animals while you are sick. If you must care for your pet or be around animals while you are sick, wash your hands before and after you interact with pets and wear a face mask.

Wear a face mask if you are sick

• Wear a face mask when you are around other people or pets and before you enter a doctor’s office or hospital.

Cover your coughs and sneezes

• Cover your mouth and nose with a tissue when you cough or sneeze and throw used tissues in a lined trash can.
• Immediately wash your hands with soap and water for at least 20 seconds after you sneeze. If soap and water are not available, clean your hands with an alcohol-based hand sanitizer that contains at least 60% alcohol.

Clean your hands often

• Wash your hands often with soap and water for at least 20 seconds, especially after blowing your nose, coughing, or sneezing; going to the bathroom; and before eating or preparing food.
• If soap and water are not readily available, use an alcohol-based hand sanitizer with at least 60% alcohol, covering all surfaces of your hands and rubbing them together until they feel dry.
• Avoid touching your eyes, nose, and mouth with unwashed hands.

Don’t share personal household items

• Do not share dishes, drinking glasses, cups, eating utensils, towels, or bedding with other people or pets in your home.
• After using these items, they should be washed thoroughly with soap and water.

Clean all “high-touch” surfaces every day

High touch surfaces include counters, tabletops, doorknobs, bathroom fixtures, toilets, phones, keyboards, tablets, and bedside tables.

• Clean and disinfect areas that may have any bodily fluids on them.
• A list of products suitable for use against COVID-19 is available here. This list has been pre-approved by the US Environmental Protection Agency (EPA) for use during the COVID-19 outbreak.

Monitor your symptoms

• Monitor yourself for fever by taking your temperature twice a day and remain alert for cough or difficulty breathing.
  • If you have not had symptoms and you begin to feel feverish or develop measured fever, cough, or difficulty breathing, immediately limit contact with others if you have not already done so. Call your doctor or local health department to determine whether you need a medical evaluation.
• Seek prompt medical attention if your illness is worsening, for example if you have difficulty breathing. Before going to a doctor’s office or hospital, call your doctor and tell them that you have, or are being evaluated for, COVID-19.
• Put on a face mask before you enter a healthcare facility or any time you may come into contact with others.
• If you have a medical emergency and need to call 911, notify the dispatch personnel that you have or are being evaluated for COVID-19. If possible, put on a face mask before emergency medical services arrive.

When can I discontinue my self-isolation or self-quarantine?

While many experts are recommending at least 14 days of self-isolation for those who are infected, the decision to discontinue these measures should be made on a case-by-case basis, in consultation with your doctor and state and local health departments. The decision will be based on the risk of infecting others.

Is there an antiviral treatment for COVID-19?

Currently there is no specific antiviral treatment for COVID-19.

What treatments are available to treat coronavirus?

Currently there is no specific antiviral treatment for COVID-19. However, similar to treatment of any viral infection, these measures can help:

• While you don’t need to stay in bed, you should get plenty of rest.
• Stay well hydrated.
• Take acetaminophen, ibuprofen, or naproxen to reduce fever and ease aches and pains. Be sure to follow directions. If you are taking any combination cold or flu medicine, keep track of all the ingredients and the doses. For acetaminophen, the total daily dose from all products should not exceed 3,000 milligrams.

Can I infect my pet?

There have not been reports of pets or other animals becoming sick with COVID-19, but the CDC still recommends that people sick with COVID-19 limit contact with animals until more information is known. If you must care for your pet or be around animals while you are sick, wash your hands before and after you interact with pets and wear a face mask.

How can I protect myself while caring for someone that may have COVID-19?

You should take many of the same precautions as you would if you were caring for someone with the flu:

• Stay in another room or be separated from the person as much as possible. Use a separate bedroom and bathroom, if available.
• Make sure that shared spaces in the home have good air flow. Turn on an air conditioner or open a window.
• Wash your hands often with soap and water for at least 20 seconds or use an alcohol-based hand sanitizer that contains 60 to 95% alcohol, covering all surfaces of your hands and rubbing them together until they feel dry. Use soap and water if your hands are visibly dirty.
• Avoid touching your eyes, nose, and mouth with unwashed hands.

Extra precautions:

• You and the person should wear a face mask if you are in the same room.
• Wear a disposable face mask and gloves when you touch or have contact with the person’s blood, stool, or body fluids, such as saliva, sputum, nasal mucus, vomit, urine.
  • Throw out disposable face masks and gloves after using them. Do not reuse.
  • First remove and throw away gloves. Then, immediately clean your hands with soap and water or alcohol-based hand sanitizer. Next, remove and throw away the face mask, and immediately clean your hands again with soap and water or alcohol-based hand sanitizer.
• Do not share household items such as dishes, drinking glasses, cups, eating utensils, towels, bedding, or other items with the person who is sick. After the person uses these items, wash them thoroughly.
• Clean all “high-touch” surfaces, such as counters, tabletops, doorknobs, bathroom fixtures, toilets, phones, keyboards, tablets, and bedside tables, every day. Also, clean any surfaces that may have blood, stool, or body fluids on them. Use a household cleaning spray or wipe.
• Wash laundry thoroughly.
  • Immediately remove and wash clothes or bedding that have blood, stool, or body fluids on them.
  • Wear disposable gloves while handling soiled items and keep soiled items away from your body. Clean your hands immediately after removing your gloves.
• Place all used disposable gloves, face masks, and other contaminated items in a lined container before disposing of them with other household waste. Clean your hands (with soap and water or an alcohol-based hand sanitizer) immediately after handling these items.

My parents are older, which puts them at higher risk for COVID-19, and they don’t live nearby. How can I help them if they get sick?

Caring from a distance can be stressful. Start by talking to your parents about what they would need if they were to get sick. Put together a single list of emergency contacts for their (and your) reference, including doctors, family members, neighbors, and friends. Include contact information for their local public health department.

You can also help them to plan ahead. For example, ask your parents to give their neighbors or friends a set of house keys. Have them stock up on prescription and over-the counter medications, health and emergency medical supplies, and nonperishable food and household supplies (see How to prepare for more detail). Check in regularly by phone, Skype, or however you like to stay in touch.

community spread (community transmission): is said to have occurred when people have been infected without any knowledge of contact with someone who has the same infection

contact tracing: a process that begins with identifying everyone a person diagnosed with a given illness (in this case COVID-19) has been in contact with since they became contagious. The contacts are notified that they are at risk, and may include those who share the person’s home, as well as people who were in the same place around the same time as the person with COVID-19 — a school, office, restaurant, or doctor’s office, for example. Contacts may be quarantined or asked to isolate themselves if they start to experience symptoms, and are more likely to be tested for coronavirus if they begin to experience symptoms.

containment: refers to limiting the spread of an illness. Because no vaccines exist to prevent COVID-19 and no specific therapies exist to treat it, containment is done using public health interventions. These may include identifying and isolating those who are ill, and tracking down anyone they have had contact with and possibly placing them under quarantine.

epidemic: a disease outbreak in a community or region

flattening the curve: refers to the epidemic curve, a statistical chart used to visualize the number of new cases over a given period of time during a disease outbreak. Flattening the curve is shorthand for implementing mitigation strategies to slow things down, so that fewer new cases develop over a longer period of time. This increases the chances that hospitals and other healthcare facilities will be equipped to handle any influx of patients.

incubation period: the period of time between exposure to an infection and when symptoms begin

isolation: the separation of people with a contagious disease from people who are not sick

mitigation: refers to steps taken to limit the impact of an illness. Because no vaccines exist to prevent COVID-19 and no specific therapies exist to treat it, mitigation strategies may include frequent and thorough handwashing, not touching your face, staying away from people who are sick, social distancing, avoiding large gatherings, and regularly cleaning frequently touched surfaces and objects at home, in schools, at work, and in other settings.

pandemic: a disease outbreak affecting large populations or a whole region, country, or continent

presumptive positive test result: a positive test for the virus that causes COVID-19, performed by a local or state health laboratory, is considered “presumptive” until the result is confirmed by the CDC. While awaiting confirmation, people with a presumptive positive test result will be considered to be infected.

quarantine: separates and restricts the movement of people who have a contagious disease, have symptoms that are consistent with the disease, or were exposed to a contagious disease, to see if they become sick

SARS-CoV-2: short for severe acute respiratory syndrome coronavirus 2, SARS-CoV-2 is the official name for the virus responsible for COVID-19.

social distancing: refers to actions taken to stop or slow down the spread of a contagious disease. For an individual, it refers to maintaining enough distance between yourself and another person to reduce the risk of breathing in droplets that are produced when an infected person coughs or sneezes. In a community, social distancing measures may include limiting or cancelling large gatherings of people.

virus: a virus is the smallest of infectious microbes, smaller than bacteria or fungi. A virus consists of a small piece of genetic material (DNA or RNA) surrounded by a protein shell. Viruses cannot survive without a living cell in which to reproduce. Once a virus enters a living cell (the host cell) and takes over a cell’s inner workings, the cell cannot carry out its normal life-sustaining tasks. The host cell becomes a virus manufacturing plant, making viral parts that then reassemble into whole viruses and go on to infect other cells. Eventually, the host cell dies.

Image: Naeblys/Getty Images

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Harvard Health Publishing Coronavirus Resource Center Experts

The Harvard Health Publishing team would like to acknowledge the Harvard Medical School experts who have contributed their time and expertise: Todd Ellerin, MD; Huma Farid, MD; Douglas Krakower, MD; Howard E. LeWine, MD; Claire McCarthy, MD; Babar Memon, MD, MSc; John Sharp, MD; Robert H. Shmerling, MD; Jacqueline Sperling, PhD.

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