How To See How Germs Can Spread (Coronavirus)
Yes, You Can Spread Coronavirus Even If You Don’t Have Symptoms
Tara C. Smith, Ph.D.
6 days ago
© Getty Middle-aged Asian man looking through a window, sipping coffee and using ideas
There’s one question about the new coronavirus that keeps coming up over and over again: Why should I have to stay at home, avoid seeing my friends, and not let my kids play with other kids if we’re all fine and healthy? None of us have symptoms, none of us have been exposed, none of us are high-risk. We don’t even have many cases in our area. Why do we still have to isolate ourselves as much as possible?
The short answer: Because we know that the new coronavirus can spread before people have symptoms. And we know that not everyone is getting tested. So, it’s entirely possible that while everyone in your immediate circle seems fine and safe, there’s (at least) one person who is unknowingly spreading the virus without any symptoms at all. It’s also possible that this is happening outside your immediate circle, but somewhere else in your town, leading to a swath of cases that no one will see coming until some people do start to have symptoms, end up in the hospital, and start getting tested.
This is why we all need to be social distancing—even when it seems like it shouldn’t apply to you.
But what we’re still figuring out is when exactly the new coronavirus is contagious in people without symptoms, when you can expect to see symptoms after being exposed, and whether or not the people who never get symptoms can still actively spread the disease around.
To sort through what we know about these questions, I reached out to virologist Chad Petit, Ph.D., an assistant professor in the Department of Biochemistry and Molecular Genetics at the University of Alabama at Birmingham, and Caroline Colijn, Ph.D., an infectious disease modeler at Simon Fraser University in Canada.
This is how a virus spreads.
First, let’s discuss what we mean when we say “viral transmission,” which refers to the process by which viruses spread from host to host. “Typically, this is person to person but can also include viruses jumping from one species to another,” Petit tells SELF. (It’s thought that the new coronavirus entered the human population through this mechanism, probably from a bat but potentially via another animal species.)
The new coronavirus mostly seems to be spreading via “droplet transmission.” This happens when someone close to you (within about six feet) is coughing, sneezing, talking, or even just breathing and releases droplets containing the virus, which can then land on your nose and mouth and enter your system. These droplets can also land on surfaces, like countertops and doorknobs, which you might then touch. If you touch your face afterward, especially your eyes, mouth, or nose, the virus can get into your body.
Once the virus is in your body, it can attach to and enter your cells. While inside a host cell, “the virus shuts down the cell’s defense mechanisms and commandeers your cell’s resources to make more viruses, essentially turning your own cell into a virus-producing factory,” each of which can release more viruses to start the process all over again on other cells, Petit says.
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This kicks off the incubation period, which is the timeframe when your body is producing more of the virus but you’re not yet showing symptoms like a fever, aches, coughing, and shortness of breath. “During this time, there may not be any clinical symptoms to alert the person that they are, in fact, infected,” Petit explains, but you could still be infecting other people. This is called “presymptomatic transmission,” and it’s the reason why you can’t just say, “Well, I’m not sick, and no one I’m spending time with is sick, and none of us have been exposed to anyone showing symptoms—so aren’t we in the clear?” Unfortunately, it doesn’t always work like that.
Research does back up the idea that people are likely spreading the new coronavirus before they have symptoms. A recent Centers for Disease Control and Prevention (CDC) rporte found that 331 of 712 people on the Diamond Princess cruise ship who tested positive for the SARS-CoV-2 virus that causes COVID-19 didn’t have any symptoms when they tested positive. That amounted to 46.5 percent of those with positive tests—so, almost half. They could have had the potential to spread the virus at that time, but we aren’t sure how much that actually happened. Another CDC article described how the new coronavirus spread from one teacher to two others during a dinner meeting on January 6. The first person in this trio to develop symptoms started feeling ill two days after the dinner, and the others—who aren’t known to have had any other potential COVID-19 exposures—developed symptoms four and six days after the dinner, respectively. They all appeared to be in fine health at the dinner, but it seems that one teacher still spread the new coronavirus to the others, who then reportedly spread it to some of their family members.
We still don’t know exactly when in the incubation period someone starts being contagious.
To determine the incubation period, we test sick individuals, figure out who they were in contact with and who might have been exposed to the virus, and then follow those exposed contacts over time to see if they get sick. If we know when those individuals were exposed and when they came down with the illness, then we can figure out the incubation period. “Currently, the incubation period typically lasts for 2 to 7 days ([with an] estimated median incubation period of 5.1 days), with 98 percent of those infected developing symptoms within 11.5 days,” Petit explains, adding that these numbers might shift when we have more information from new cases. A small percentage of people seem not to show symptoms until closer to 14 days.
But that still doesn’t tell us exactly when during the incubation period a person can spread the virus. It can’t be right at the beginning, because the virus hasn’t started to grow inside a person’s system at that point. Colijn is currently working on a project to figure this out.
“We can compare two things: (a) the incubation period,” she tells SELF, “and (b) the serial interval, the time between one person getting symptoms and someone they infected getting symptoms.” Colijn and her fellow researchers have described their findings in this study, which hasn’t yet been peer-reviewed but still offers interesting insights into this question. When analyzing information from Singapore and Tianjin, China, they found that the serial interval was shorter than the incubation period, meaning people seem able to spread the new coronavirus before they feel sick. Specifically, the study suggests that people may be able to transmit the virus to others at least three days before their own symptoms develop.
And what about people who test positive but never seem to develop symptoms?
The CDC study of cruise ship COVID-19 transmission determined that almost 18 percent of people on the Diamond Princess who had the new coronavirus never showed symptoms at all, then recovered. They apparently remained asymptomatic.
“Data on those who are completely asymptomatic is a major gap right now,” Colijn says. She explains that we can start to fill this gap when we can do large-scale serological tests to measure COVID-19 antibodies in people’s blood. This will tell us who was exposed to the virus at some point in the past but may never have known they were infected because they never felt ill. But until we have those widespread testing capabilities, we won’t have the full picture of who exactly is spreading the virus and when.
If people can spread the virus before they have symptoms, controlling the spread requires drastic measures.
For now, we’re still left with questions about how and when asymptomatic and presymptomatic COVID-19 spread is occurring. But we do know this: An outbreak is more difficult to control if we can spread the disease even when we don’t have symptoms. Yes, as Petit notes, it can seem completely counterintuitive that you could have COVID-19 but feel fine. But when people try to go about their daily lives as much as possible right now, it’s enhancing the spread of the virus, Petit explains. There’s really no way around that. This means that we can’t just take precautions if we’re feeling sick or think we’ve been exposed to someone who is sick.
This is why social distancing is critical right now (along with other important practices like washing your hands well and often). It’s why we’re telling you not to meet up with your friends, or go out to the bar that’s still open in your town, or schedule a playdate for your kids, or otherwise carry on as you normally would. We can’t just assume that we would know if someone was transmitting the virus. Because, at this point, we don’t.
Even if you think your risk of getting sick is low, don’t let that perception make you feel like the rules don’t apply to you. You have no way of knowing if anyone you come into contact with has the virus or was recently exposed to someone who does, regardless of symptoms. And if you think you’re not at risk because you’re young and healthy, you should know that experts are starting to realize even younger people with no underlying health conditions can become extremely sick and, tragically, even die from COVID-19.
“We will be unlikely to control this by only isolating ill people,” Colijn says. “[There’s] need for broader measures—keeping away from each other—even if we don't know that we are sick.” She also cautions patience and notes that we won’t see the effects of social distancing immediately. “Cases that are confirmed today were infected some time ago, and we have only just started seriously physically distancing ourselves,” she says. “So take heart,” she adds. “We hope to see the results soon.”
20 Things That Put You at Risk for Coronavirus
Kelly Hernandez
3/28/2020
20 Things That Put You at Risk for Coronavirus
You think you're safe from coronavirus (COVID-19) by following all the rules. But that doesn't mean you're not at risk. If you fall into a high-risk category, it's even more crucial to protect yourself. Review these 20 things that put you in danger so you can learn how to be even more cautious—saving your life and someone else's.
1. First, the Obvious: You’re 65 or Older
COVID-19 doesn't discriminate and you're susceptible to infection no matter your age. But if you're 65 or older, it's more likely that the virus could lead to severe illness and complications that may lead to hospitalization—or even death. According to the CDC, "8 out of 10 deaths reported in the U.S. have been in adults 65 years old and older."
The Rx: This statistic may be due to how common it is for older folks to have underlying health conditions. It may also be due to a weakened immune system as we age. No matter the reason, if you're 65 or older, it's crucial to do all you can to stay away from this virus since it could be deadly.
2. You’re Still Running Errands
Do you really need that pint of ice cream? Is it a good time to go window shopping for a new vacuum? No. Whether your area is under "shelter in place," "stay at home," or just "social distancing" orders, it's not a good time to cross things off your to-do list that involves public places. That's because the coronavirus is way more contagious than the flu or other airborne illnesses. "Based on most estimates, each infected person is infecting between two and three additional people," says Dr. Ranu S Dhillon, MD, from Harvard Medical School.
The Rx: Before you leave your house, ask yourself if it's essential right now. Runs for groceries or medications are understandable, but even those can be delivered. It's important to limit your time in public as much as possible.
3. You Live in a Nursing Home or Long-Term Care Facility
The CDC warns that long-term care facility residents or nursing home residents are at higher risk of contracting COVID-19. They're living together in a group and having staff (who may be in and out of the facility) taking care of them, which increases risk for exposure. Since most residents are older and may already have health complications, they're also at higher risk for severe illness related to the virus.
The Rx: If you or a loved one live in a nursing home or long-term care facility, limit contact with staff and other residents as much as possible. Consider taking meals in your room and other precautions, including frequent handwashing and disinfecting surfaces in the room. And if you know someone in a nursing home, don't expect to visit unless extenuating circumstances permit it.
4. You’re Touching Surfaces While in Public
If you're out running your essential errands, be careful about touching products, materials, and surfaces. According to the National Institutes of Health (NIH), COVID-19 is detectable for "up to four hours on copper, up to 24 hours on cardboard, and up to two to three days on plastic and stainless steel."
The Rx: It's impossible to grab the groceries you need without touching surfaces and packaging, but attempt to minimize what you touch as much as possible. When you're in public, don't put your fingers in your mouth or touch your face until you get home and can conduct a thorough hand washing. Wear gloves when outside—even washable winter ones will do.
5. You Have a Chronic Lung Disease
COVID-19 is a virus that attacks the lungs. Lung diseases, such as lung cancer, mesothelioma, chronic obstructive pulmonary disease (COPD), or emphysema, don't necessarily increase your risk for contracting COVID-19. However, if you live with lung disease or lung issues in general, you're at a higher risk for complications due to infection of the virus, including hospitalization, permanent lung damage, or even death.
The Rx: If you have a chronic lung disease, take every precaution you can to limit your exposure to the virus, including wearing a mask and gloves when in public. If you're a smoker, quit now!
6. You Have Asthma
The health and stability of your lungs is an important factor for how your body is affected by coronavirus if you contract it. If you have asthma, you're at higher risk for experiencing severe complications. According to the CDC, if you have asthma, the coronavirus "can affect your respiratory tract (nose, throat, lungs), cause an asthma attack, and possibly lead to pneumonia and acute respiratory disease."
The Rx: Limit your potential exposure to the virus by socially isolating. Keep your home and environment clean and disinfected. Continue taking asthma medication and avoiding asthmatic triggers, especially stress or polluted air.
7. You’re Getting Deliveries Without Cleaning the Items
You're following all the precautions to lower your risk of contracting COVID-19 by having your groceries, food, medicine, and supplies delivered to your doorstep. It's smart to avoid public places, but your delivered items may also bring the virus into your home. Since the virus actively lives on surfaces for hours and days, delivered food and medicines aren't safe either.
The Rx: According to the CDC, "Cleaning of visibly dirty surfaces followed by disinfection is a best practice measure for prevention of COVID-19 and other viral respiratory illnesses in households and community settings." When you receive a package, throw away packaging and wipe down all items with disinfecting spray or wipes. Wash your hands thoroughly after touching delivered items.
8. You’re Living With a Serious Heart Condition
Your current health determines whether or not you're at risk for developing serious complications related to COVID-19. If you have a heart condition, such as heart disease, your risks are definitely higher. According to a bulletin released in February by the American College of Cardiology, "40% of hospitalized COVID-19 patients had cardiovascular disease or cerebrovascular disease (which refers to blood flow in the brain, such as stroke)." The virus attacks the lungs but if your heart has to work harder to function normally, both your respiratory and cardiovascular systems are compromised.
The Rx: If you have a heart condition, take extra precautions to avoid public places. Wear gloves and a mask if you must go out in public and ensure your home, car, and other environments remain disinfected. If you take medication for your heart condition, have at least a two months supply on hand and continue following your doctor's orders.
9. You’re Visiting Friends and Family
Self-isolation gets boring so you head over to your friend's house to play a game of Scrabble. You're not spending time in public or with a big group and your friend feels healthy, so it's okay, right? Wrong. Even if your friends and family have been social distancing and don't feel any symptoms of the virus, it doesn't mean they aren't infected. According to Harvard Medical School, "Some people infected with the virus have no symptoms."
The CDC also warns that after exposure to the virus, it can take two to 14 days before you begin to feel symptoms, if you do at all. If you spend time with friends or family members who are unknowingly infected, you can easily catch the virus as well and spread it to many others.
The Rx: If you feel fine and your friends and family members also feel fine, it's tempting to spend time together. To adhere to social distancing, however, it's important to avoid spending time with anyone who doesn't live in your household. Try video chats or conference calls to keep in touch with loved ones instead.
10. You Have a Weakened Immune System
Your immune system is key in fighting off the virus if you become infected. If you have a healthy immune system, you're more likely to experience mild symptoms from COVID-19 and recover quickly. However, if you have an autoimmune disease or are immunocompromised in some way, your risk for experiencing severe and serious symptoms from coronavirus increases. This includes those who have HIV or AIDS or who are undergoing cancer treatments, such as radiation or chemotherapy.
According to Dr. Paul Volberding from the University of California, "Being immunocompromised might not so much increase your likelihood of getting infected with something like COVID-19 but it might make the outcome of that infection much worse."
The Rx: While you may feel fine, it's important to treat yourself as a high-risk patient as the virus spreads. Take the rules of social distancing seriously and avoid contact with others at all costs.
11. You Have Diabetes
If you're living with diabetes, there's not a higher likelihood that you'll contract coronavirus. However, if you do become infected with the virus, there's a greater chance that you'll experience severe symptoms, such as fever or pneumonia. According to the American Diabetes Association, in China it was found that "people with diabetes had much higher rates of serious complications and death than people without diabetes."
The Rx: If you're living with diabetes, reduce your vulnerability for contracting the virus by isolating yourself from the general public. Keep yourself healthy and your immune system strong by continuing to monitor your disease as normal and taking all medications as directed by your doctor.
12. You’re Exposing Yourself to Large Crowds
The more people you expose yourself to in large crowds, whether it's at a park or at the grocery store, the higher your risk for contracting COVID-19. Whether you fall into the "high risk" category or not, your adherence to social distancing techniques is crucial to stop the spread of the virus.
The Rx: Implement social distancing techniques, including avoiding large crowds, immediately. Try to only interact with those who live in your household. If you venture out to a nearby park and see a large crowd, go somewhere else. Try to stay at least six feet from others whenever possible.
13. You’re Congregating With Your Neighbors
Being cooped up in your house for weeks gets boring, especially if you run out of quarantine snacks. But you better think twice before you desperately knock on your neighbor's door with a bottle of wine for some much-needed social interaction. Don't assume it's okay to hang out with them because they look "healthy." It's possible for those infected with COVID-19 to never feel symptoms of the virus, and you don't know if their definition of self-isolation is the same as yours—the exposure is not worth that bottle of Sancerre.
The Rx: While socially isolating makes for long and boring days, it's important to stay at home and only socialize with your own household members. If you miss your neighbors, take out some sidewalk chalk and write each other messages. Call out to each other from your porches or exchange numbers and keep in touch through text messaging or a Slack group chat.exchange numbers and keep in touch through text messaging or a Slack group chat.
14. You’re Overweight
According to the University of California San Francisco Health Department, "An estimated 60% of Americans aged 20 years and older are considered overweight and one-quarter are considered obese." Not only does obesity increase your risk for heart disease, type 2 diabetes, high blood pressure, and stroke, being overweight may also affect how your body deals with the coronavirus.
If you're infected with COVID-19 and you're overweight or obese, you're at higher risk for developing complications, including pneumonia. Extra weight makes your heart and lungs have to work harder during everyday tasks, so if you contract a virus that attacks your lungs, it's more likely you'll experience complications and may need to seek medical treatment.
The Rx: If you're overweight or obese, it's even more important to follow social distancing protocol. Avoid public places where you may contract the virus and implement thorough hand washing techniques. Your health should be your top priority, so listen to your doctor's advice on maintaining a healthy weight through diet and exercise
15. You Recently Had a Bone Marrow or Organ Transplant
Individuals who have had a bone marrow or organ transplant are known to have weaker immune systems. The American Society of Transplantation addresses the concerns of transplant and bone marrow recipients under the recent COVID-19 outbreak. "We do not have specific information on whether COVID-19 infection will be more severe in transplant recipients compared to healthy people; however, other viruses often cause more severe disease in people whose immune system is low, such as transplant recipients."
The Rx: The American Society of Transplantation urges all organ and bone marrow transplant patients to follow protocols and guidelines set by the CDC. This includes restricted travel and sheltering in place. The organization also warns patients to reduce their risk of contracting the virus by isolating themselves from friends and family members who may have been exposed to the virus.
16. You’re Out and About Without Protection
If you're 65 and over, immunocompromised, overweight, or have another medical condition that makes you high-risk for complications from the coronavirus, avoid visiting public places as much as possible. If you stay in your home with only household members you know haven't been exposed to the virus and ensure your environment stays sanitized and disinfected, you're decreasing your risk of contracting the virus.
Ask family members, friends, or neighbors who don't have these high-risk factors to run your errands for you. If you have to go out in public and there's no avoiding it, wear protection. Without protection, you're more vulnerable to the virus on surfaces you touch or from the droplets of other peoples' coughs and sneezes.
The Rx: Those without high risk aren't advised to wear face masks when in public. However, if you do fall into the high-risk category, don't leave home without a mask and gloves. Wear these protective items throughout the duration of your time in public, then throw them away as soon as your errands are completed. Even if you wore a face mask and gloves, wash your hands and clothes as soon as you get home to kill any potentially lingering bacteria.
17. You’re Not Washing Your Hands Properly
Washing your hands frequently is one of the best ways to keep the virus and other germs at bay. It's even more important to thoroughly wash your hands after coughing, sneezing, before and after eating, or after spending time in a public place. If you're in a hurry or you don't have the right items for a proper handwashing, however, you're not doing much. A quick rinse in water doesn't kill the virus or other germs that may be on your hands.
The Rx: The World Health Organization (WHO) advises that you use an alcohol-based hand rub or soap and water and wash your hands often. The CDC recommends scrubbing your hands with soap, preferably antibacterial, for at least 20 seconds, being sure to thoroughly rub in between fingers, on the backs of hands, and under fingernails, before rinsing under running water.
18. You Can’t Break the Habit of Touching Your Face
You've probably already heard the advice from the CDC to stop touching your face as a way to prevent spreading the virus. According to the Association for Professionals in Infection and Control and Epidemiology, people touch their face about 23 times every hour.
COVID-19 is spread from exposure to droplets that come from an infected person sneezing and coughing. If these droplets land on your hands or fingers and you touch your face, you can easily infect yourself through your eyes, nose, or mouth.
The Rx: It's a tough habit to break, but it's crucial to refrain from touching your face, nose, and mouth, especially when you're in public. Identifying your triggers helps. If you truly have an itch or need to touch your face, it's only safe to do so after you've properly washed your hands. Better yet: Use a tissue instead of your fingers.
19. You’re Using Public Transportation
In most areas, public transportation, including the bus and train systems, are still open to the general public. For some, this is the only way they can get to essential jobs or travel to grocery stores. But these modes of transportation put you at higher risk of contracting the virus. According to the CDC, "Crowded travel settings, like airports, may increase chances of getting COVID-19, if there are other travelers with coronavirus infection."
The Rx: Avoid air travel at all costs, since it increases your risk for exposure. In your daily life, if you have other methods of transportation available to run your essential errands, such as your own car, a bike, or walking, choose these modes instead of public transit. Decreasing the amount of contact you have with others also decreases your risk for contracting COVID-19.
20. You’re Not Taking It Seriously
Even if you don't fall into a high-risk category, it's important to take this pandemic seriously. When you're careless with your actions and don't take the proper precautions, you increase your risk for infection and other people around you.
The Rx: Follow CDC guidelines for proper handwashing, disinfecting your home, and the handling of goods. Keep abreast on updates in your area and follow all shelter-in-place and social distancing orders as they're enforced. You can minimize the negative effects of COVID-19 by doing everything you can to lower your risk of infection and the spread of the virus.
And to get through this pandemic at your healthiest, don't miss these 50 Things You Should Never Do During the Coronavirus Pandemic.