Coronavirus Resource Center

As coronavirus spreads, many questions and some answers

The rapid spread of the virus that causes COVID-19 continues to spark alarm worldwide. Countries around the world are grappling with surges in confirmed cases, hospitalizations, and deaths. Calls for preventive measures such as social distancing and face coverings to slow the spread of coronavirus have created a new normal in many places. Health care workers and hospitals have ramped up capabilities to care for large numbers of people made seriously ill by COVID-19. Meanwhile, scientists are exploring potential treatments and clinical trials to test new therapies and vaccines are underway.

Below, you'll find answers to common questions all of us are asking. We will be adding new questions and updating answers as reliable information becomes available. Also see our podcasts featuring experts discussing coronavirus and COVID-19.

Symptoms, spread, and other essential information

What is coronavirus and how does it spread? What is COVID-19 and what are the symptoms? How long does coronavirus live on different surfaces? Take a moment to reacquaint yourself with basic information about this virus and the disease it causes.

Click here to read more about COVID-19 symptoms, spread, and other basic information.


Social distancing, hand washing, and other preventive measures

By now, many of us are taking steps to protect ourselves from infection. This likely includes frequent handwashing, regularly cleaning frequently touched surfaces, and social distancing. How do each of these measures help slow the spread of this virus, and is there anything else you can do?

Click here to read more about what you can do to protect yourself and others from coronavirus infection.


If you are at higher risk

Though no one is invulnerable, we've seen that older adults are at increased risk for severe illness or death from COVID-19. Underlying conditions, including heart disease, lung disease, and diabetes, increase risk even further in those who are older. In addition, anyone with an underlying medical condition, regardless of their age, faces increased risk of serious illness.

Click here to read more about what you can do if you are at increased risk for serious illness.


If you've been exposed, are sick, or are caring for someone with COVID-19

Despite your best efforts, you may be exposed to coronavirus and become ill with COVID-19. Or you may be in a position where you are caring for a loved one with the disease. It's important to know what to do if you find yourself in any of these situations. Stock up with medications and health supplies now, and learn the steps you can take to avoid infecting others in your household and to avoid getting sick yourself if you are caring for someone who is ill.

Click here to read more about what to do you if you have been exposed, are sick, or are caring for someone with COVID-19.


Treatments for COVID-19: What helps, what doesn't, and what's in the pipeline

While there are no specific treatments for COVID-19 at this time, there are things you can do to feel better if you become ill. In the meantime, researchers around the globe are looking at existing drugs to see if they may be effective against the virus that causes COVID-19, and are working to develop new treatments as well.

Click here to read more about measures that can help you feel better and treatments that are under investigation.


Coronavirus and kids:

So far, the vast majority of coronavirus infections have afflicted adults. And when kids are infected, they tend to have milder disease. Still, as a parent, you can't help but worry about the safety of your children. Many parents are also trying to find a balance between answering their children's questions about the pandemic and enforcing health-promoting behaviors and social distancing rules without creating an atmosphere of anxiety. Not to mention keeping kids engaged and entertained with schools closed and playdates cancelled.

Click here to read more about kids and the coronavirus outbreak.


Coping with coronavirus:

The news about coronavirus and its impact on our day-to-day lives has been unrelenting. There's reason for concern and it makes good sense to take the pandemic seriously. But it's not good for your mind or your body to be on high alert all the time. Doing so will wear you down emotionally and physically.

Click here to read more about coping with coronavirus.


New questions and answers

Could wearing masks prevent COVID deaths?

According to a new study published in the journal Nature Medicine, widespread use of masks could prevent nearly 130,000 of 500,000 COVID-related deaths estimated to occur by March 2021.

These numbers are based on an epidemiological model. The researchers considered, state by state, the number of people susceptible to coronavirus infection, how many get exposed, how many then become infected (and infectious), and how many recover. They then modeled various scenarios, including mask wearing, assuming that social distancing mandates would go into effect once the number of deaths exceeded 8 per 1 million people.

Modeling studies are based on assumptions, so the exact numbers are less important than the comparisons of different scenarios. In this study, a scenario in which 95% of people always wore masks in public resulted in many fewer deaths compared to a scenario in which only 49% of people (the self-reported national average of mask wearers) always wore masks in public.

This study reinforces the message that we can help prevent COVID deaths by wearing masks.

What does the CDC's new definition of "close contacts" mean for me?

The CDC has expanded how it defines close contacts of someone with COVID-19. Until this point, the CDC had defined a close contact as someone who spent 15 or more consecutive minutes within six feet of someone with COVID-19. According to the new definition, a close contact is someone who spends 15 minutes or more within six feet of a person with COVID-19 over a period of 24 hours.

Close contacts are at increased risk of infection. When a person tests positive for COVID-19, contact tracers may identify their close contacts and urge them to quarantine to prevent further spread. Based on the new definition, more people will now be considered close contacts.

Many factors can affect the chances that infection will spread from one person to another. These factors include whether or one or both people are wearing masks, whether the infected person is coughing or showing other symptoms, and whether the encounter occurred indoors or outdoors. Though the "15 minutes within six feet rule" is a helpful guideline, it's always best to minimize close interactions with people who are not members of your household.

The CDC's new definition was influenced by a case described in the CDC's Morbidity and Mortality Weekly Report in which a correctional officer in Vermont is believed to have been infected after being within six feet for 17 non-consecutive minutes of six asymptomatic individuals, all of whom later tested positive for COVID-19.

How does obesity increase risk of COVID-19?

According to a recent review and meta-analysis that looked at 75 international studies on the subject, obesity is a significant risk factor for illness and death due to COVID-19.

When looking at people with COVID-19, the analysis found that, compared with people who were normal weight or overweight, people who were obese were

  • more than twice as likely to be hospitalized
  • if hospitalized, nearly 75% more likely to be admitted to the intensive care unit (ICU)
  • almost 50% more likely to die of COVID-19.

Obesity may impact COVID risk in several ways. For example, obesity increases the risk of impaired immune function and chronic inflammation, both of which could make it harder for the body to fight the COVID-19 infection. Excess fat can also make it harder for a person to take a deep breath, an important consideration for an illness that impairs lung function.

People who are obese are also more likely to have diabetes and high blood pressure, which are themselves risk factors for severe COVID-19. And obesity is more common in Black, Latinx, and Native Americas, who are more likely to get infected and die from COVID-19 than whites for a variety of reasons.

If you have obesity (defined as a body mass index, or BMI, of 30 or higher), stay vigilant about protecting yourself from infection. That means maintaining physical distance, avoiding crowds when possible, wearing masks, and washing your hands often.

Why do some people get very sick from COVID-19 while others do not?

One of the most perplexing aspects of coronavirus is why it strikes people so differently. Why do some people sail through without a symptom, while others — even some who are otherwise healthy and relatively young — get extremely sick or even die? It may have to do with interferons.

New research suggests that up to 14% of people who develop severe COVID-19 have an inadequate interferon response. In some people, this happens because their own antibodies mistakenly attack and neutralize their interferons. Others have a genetic mutation that prevents their body from producing enough of a certain type of interferon.

Interferons are an important component of innate immunity, the quick, nonspecific immune defense the body mounts within minutes of infection to rid the body of invaders. Interferons help protect the body in a number of ways: they signal nearby cells to guard themselves against invasion; they signal infected cells to die; and they activate the adaptive immune system to mount a specific, long-term antibody response. An inadequate interferon response could help explain why some people — especially some young people without underlying conditions — get so much sicker than others their age.

Interferon treatments do exist to treat other illnesses. And interferon inhalers were given to healthcare workers in China to help prevent infection. But treatments come with their own risks, and questions about dose, timing, and type of interferon would need to be resolved before interferon therapy could be safely used for COVID-19.

Another important reason for differences in severity of COVID-19 illness is also related to the immune system. If the immune system doesn't turn off once the virus is controlled, it can go into overdrive. The result: an intense and widespread inflammatory response damaging tissues throughout the body. This is often referred to as cytokine storm.

Who are long haulers? And what is post-viral syndrome?

Long haulers are people who have not fully recovered from COVID-19, weeks or even months after first experiencing symptoms. Post-viral syndrome, or post-COVID-19 syndrome, refers to the constellation of symptoms long-haulers are experiencing.

As the pandemic has worn on, it's become clear that not everyone is recovering from COVID-19 as quickly as expected. Some people continue to experience symptoms for weeks or even months. Others feel better for weeks, then relapse with old or new symptoms.

It's difficult to predict who will become a long hauler. Many long haulers initially had mild to moderate symptoms and did not require hospitalization. Previously healthy young adults, not just older adults with coexisting medical conditions, are also experiencing post-COVID-19 syndrome.

Symptoms of post-COVID-19 syndrome, like symptoms of COVID-19 itself, can vary widely. Some of the more common lasting symptoms include fatigue, brain fog, shortness of breath, chills, body ache, headache, joint pain, chest pain, cough, and lingering loss of taste or smell. The common thread is that long haulers haven't returned to their pre-COVID health, and ongoing symptoms are negatively affecting their quality of life.

There's already some speculation, but no definite answers, about what is causing these ongoing symptoms. Some researchers suspect that SARS-CoV-2 infection triggers long-lasting changes in the immune system. Others propose that it triggers autonomic nervous system dysregulation, which can impact heart rate, blood pressure, and sweating, among other things.

Many long haulers never had laboratory confirmation of COVID-19, which can make it tricky to diagnose post-COVID-19 syndrome. Early on in the pandemic, tests were scarce. Many people who suspected they had COVID-19 self-isolated without getting a test, or were refused a COVID test when they requested one. And the tests themselves have not been entirely reliable; both diagnostic tests and antibody tests may return false negative results if taken too early or too late in the course of illness.

Has a mutation made it easier for the COVID-19 virus to spread?

Like other viruses, the coronavirus responsible for COVID-19 — SARS-CoV-2 — cannot survive without a living cell in which to reproduce. Once it enters human cells, SARS-CoV-2 churns out copies of itself, which go on to infect other cells.

Sometimes, a mistake is made when the virus is replicating. This is called a mutation. A mutation of the original SARS-CoV-2 virus — the D614G variant — has quickly become the most prevalent form of the virus seen around the world.

This mutation occurred on the coronavirus's spike proteins, protrusions on the surface of the virus that open the host cell and allow the virus to enter. About 1,300 amino acids serve as building blocks for a spike protein. In the D614G variant, the genetic instructions for just one of the spike protein's amino acids — number 614 — switched in the new variant from a "D" (short for aspartic acid) to a "G" (short for glycine).

Evidence is building that the D614G strain may spread more easily than the original strain. Infected individuals with this strain appear to have more virus in their upper respiratory tracts, and therefore may be more likely to spread infection to others. So far, the mutated strain has NOT seemed to cause more severe disease.

Mutations of coronaviruses, like all viruses, are to be expected. Scientists working on vaccines take this into account.

Whether people previously infected with the original strain can be infected again with this new and now more dominant strain is not yet known. But it's another reason why physical distancing, avoiding crowds when possible, wearing masks, and hand washing remain our best defense.

Which precautions are really necessary when it comes to preventing COVID-19?

Wear masks. Physically distance. Socialize outdoors. Avoid crowded indoor spaces. Wash your hands frequently. These are essential precautions you should take to reduce your risk of catching or spreading coronavirus.

But what about some other precautions you may be taking? Do they help, or is it okay to let them go? Let's take a look.

You don't need to wear gloves when running errands. It's true that a person can get infected if they touch a surface or object that has viral particles on it, then touch their mouth, nose, or eyes. But this is not the main way the virus spreads. What's more, gloves won't prevent this type of transmission, and may even make it more likely that you will touch your face. Instead, wash your hands before you leave the house, use hand sanitizer when you're out and about, and wash your hands again when you get back home. In between, try to avoid touching your face.

You don't need to disinfect groceries or takeout containers. The risk of infection from food or food packaging is very small. The CDC advises against using disinfectant intended for hard surfaces on cardboard or other grocery items, which can absorb the chemicals. If you are concerned about takeout, transfer food to your own serving dishes. And wash your hands and disinfect your counters after putting away your groceries or handling takeout containers.

Your mail can come out of quarantine. Mail does not pose a large risk, and putting your mail aside for several days before opening it is unnecessary. Once again, your best bet is to wash your hands after handling anything you bring in from outside.

You can invite your cleaners back into your home. If you've asked your cleaners to come back, request that they wear masks the entire time they are in your home. Leave the house while the cleaners are present if you can; otherwise, move to a different part of the house and close the door. Open windows to increase airflow throughout the house.

It's okay to go for a swim. Pools are relatively safe, because the coronavirus doesn't spread through water and chlorine is a disinfectant. Try to maintain physical distancing in crowded pools, but don't wear cloth masks in the water: they are difficult to breathe through when wet. Do wear a mask when changing, however, and minimize time in changing rooms, which are often crowded and not well ventilated.

The FDA recently granted emergency use authorization to a new rapid antigen test for COVID-19. How is it different from other tests on the market?

The FDA recently granted emergency use authorization (EUA) for a new diagnostic test for COVID-19. Results from this inexpensive test are available within 15 minutes.

The BinaxNOW COVID-19 Ag Card, as the test is known, detects antigen proteins on the surface of SARS-CoV-2, the virus that causes COVID-19. Unlike other diagnostic tests for COVID-19, BinaxNOW does not require a laboratory or other equipment to process or analyze the test results. This makes it portable and fast.

This test is approved for use in people who are suspected of having COVID-19, and must be done within seven days of when their symptoms began. A prescription is needed to get this test, which can be performed in authorized locations including doctor's offices and emergency rooms.

To perform the test, a sample obtained using a nasal swab is inserted into the BinaxNOW test card. The test is a lateral flow immunoassay, which works like a pregnancy test. The appearance of colored lines on the test strip indicates whether or not you have tested positive for COVID-19. The test comes with a smartphone app that can be used to share test results.

Positive test results are highly specific, meaning that if you test positive you are very likely to be infected, particularly if you are tested during the first week of infection when you are experiencing symptoms. False negatives are a bigger concern. As with other antigen tests, BinaxNOW can miss infections, producing negative test results in people who are actually infected.

Still, this test could have an important role during this pandemic. It offers a quick, easy, and inexpensive way to test more people, more quickly.

Is a person who has been infected with coronavirus protected from becoming infected again?

Most people who are infected with the COVID-19 virus produce antibodies, which are proteins that make it harder for the virus to infect cells. But antibodies are only one part of the body's immune response. T cells, for example, can destroy cells that are already infected. And memory B cells can quickly generate a strong antibody response to a virus the body has encountered before.

Antibody levels typically fall once the immediate threat of infection declines. Several new studies have found that COVID-19 antibody levels decline, but then stabilize and remain in the blood even two to three months after infection. Other recent studies found COVID-specific B cells and T cells in the blood, months after people recovered. This all suggests that the immune system would be ready to react quickly and strongly if re-exposed to the COVID-19 virus.

The laboratory evidence is promising. But the real evidence will come as more and more people who have recovered (rather than cells in a lab) are re-exposed to the virus.

Researchers in Hong Kong recently reported the first confirmed case of reinfection with the COVID-19 virus. The man was first infected in March, then declared to be recovered after two negative coronavirus tests. Four and a half months later, he tested positive for coronavirus on a saliva screening test administered at the Hong Kong airport upon his return from a trip to Europe. Scientists sequenced viral genetic material from the man's two infections and found significant enough differences to suggest two separate infections.

The man had experienced mild symptoms during his first infection and had no symptoms the second time he was infected. It's possible that while his immune system could not protect him against reinfection, it did help keep him from getting sicker during the second infection.

It's far too early to make any generalizations. We cannot know from one case of reinfection (among tens of millions of people who have been infected) how strong an average immune response will be, or how long that immune response will last.

It's also worth noting that someone who has been re-infected — even someone with no symptoms — has the potential to spread the virus to others. That means that everyone, even those who have recovered from coronavirus infection, should continue to wear masks and practice physical distancing.

What types of masks are most and least effective?

We know that wearing masks can help prevent the spread of coronavirus by blocking droplets that are emitted when someone coughs, sneezes, talks, or breathes. But which masks are best and worst?

Researchers at Duke University created a simple setup that allowed them to count the number of droplet particles released when people spoke the phrase "Stay healthy, people" five times in a row. First, the study participants spoke without a mask, and then they repeated the same words, each time wearing one of 14 different types of face masks and coverings.

As expected, medical grade N95 masks performed best, meaning that the fewest number of droplets got through. They were followed by surgical masks. Several masks made of polypropylene, a cotton/propylene blend, and 2-layer cotton masks sewn in different styles also performed well.

Gaiters ranked dead last. Also called neck fleeces, gaiters tend to be made of lightweight fabric and are often worn by athletes. Bandanas also ranked poorly.

A couple of simple tests can help you gauge the effectiveness of your mask: If you can see through your mask when you hold it up to the light, or can breathe through it easily, it's probably not doing much to prevent spread.


More about COVID-19


Podcast: Thoughts on COVID-19 during this year's flu season (recorded 10/9/2020)

With the COVID-19 pandemic still ongoing, and the annual flu season fast approaching, what can people expect when these two illnesses collide? Are we at greater risk for getting either virus? And could this encounter change how we approach health care now and in the future? Matthew Solan, executive editor of the Harvard Men's Health Watch, talks to Dr. Amy Sherman, an infectious disease expert with Harvard's Brigham and Women's Hospital, about what we may expect when COVID and the flu season meet. To learn more check out our Harvard Medical School Guide, COVID-19, Flu and Colds.

Podcast: Back to school: It's never been more complicated (recorded 7/30/2020)

Sending kids back to school in the fall is always a hopeful time in America. For most families, school is a vital part of the community. With the surge in coronavirus in many areas of the country, getting kids back in the classroom safely will require a major re-evaluation to reduce transmission rates that can impact people of all ages. We talked to Allan Geller, a senior lecturer in the Department of Social and Behavioral Sciences at Harvard's T.H. Chan School of Public Health. Like it or not, for school teachers and administrators, things are going to be different. Don't expect the traditional.

Podcast: Coronavirus Update: We're facing the start of a second wave (recorded 6/11/2020)

Dr. Ashish K. Jha, head of the Harvard Global Health Institute, offers information on where we are where we're going with the COVID-19 outbreak. Some take-aways:

  • Communications missteps by the WHO regarding asymptomatic transmission have been quickly corrected. Yes, you can catch COVID-19 from people who are not showing symptoms.
  • A second wave has begun, particularly in the south and Midwest. And calculations show we'll reach more than 200,000 COVID-19 related deaths by September.
  • Jha offers advice for parents, teachers and administrators on workable back-to-school scenarios.
  • We know you don't want to hear it, but COVID-19 will be a fact of global life for the rest of the year until a vaccine becomes widely available.


Reliable resources


Terms to know:

aerosols: infectious viral particles that can float or drift around in the air. Aerosols are emitted by a person infected with coronavirus — even one with no symptoms — when they talk, breathe, cough, or sneeze. Another person can breathe in these aerosols and become infected with the virus. Aerosolized coronavirus can remain in the air for up to three hours. A mask can help prevent that spread.

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

physical distancing: also called 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 physical distance (a minimum of six feet) between yourself and another person to reduce the risk of breathing in droplets or aerosols that are produced when an infected person breathes, talks, coughs, or sneezes.

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: also called physical distancing, refers to actions taken to stop or slow down the spread of a contagious disease. For an individual, it refers to maintaining enough physical distance (a minimum of six feet) between yourself and another person to reduce the risk of breathing in droplets or aerosols that are produced when an infected person breathes, talks, coughs, or sneezes. It is possible to safely maintain social connections while social distancing, through phone calls, video chats, and social media platforms.

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


Questions?

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: Steven A. Adelman, MD; Ashwini Bapat, MD; Suzanne Bertisch, MD, MPH; Joseph R. Betancourt, MD, MPH; Emeric Bojarski, MD; Andrew E. Budson, MD; Stephanie Collier, MD, MPH; Todd Ellerin, MD; Huma Farid, MD; Robert Gabbay, MD, PhD, FACP; Alan Geller, MPH, RN; Ellen S. Glazer, LICSW; Peter Grinspoon, MD; Sabra L. Katz-Wise, PhD; Anthony Komaroff, MD; Douglas Krakower, MD; Debi LaPlante, PhD; Howard E. LeWine, MD; Dara K. Lee Lewis, MD; Sharon Levy, MD, MPH; Kristina Liu, MD, MHS; Julia Marcus, PhD, MPH; Luana Marques, PhD; Claire McCarthy, MD; Chris McDougle, MD; Babar Memon, MD, MSc; Uma Naidoo, MD; Janelle Nassim, MD; Vikram Patel, MBBS, PhD; Edward Phillips, MD; Shiv Pillai, PhD, MBBS; Lee H. Schwamm, MD; Howard J. Shaffer, PhD, CAS; John Sharp, MD; Robert H. Shmerling, MD; Jacqueline Sperling, PhD; Fatima Cody Stanford, MD, MPH, MPA, FAAP, FACP, FTOS; Monique Tello, MD, MPH; Robyn Thom, MD; Karen Turner, OTR/L; Scott Weiner, MD; Anna R. Wolfson, MD.

Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.