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5 Things Everyone Should Know About the Coronavirus Outbreak

BY KATHY KATELLA July 26, 2021

Advice is changing as U.S. rolls out vaccines.

[Originally published: January 29, 2020. Updated: July 26, 2021.] 

COVID-19 upended daily life in the United States as SARS-CoV-2, the virus spreading the disease, caused surges in infections across the country. After more than a year of adjusting to strict guidelines, many Americans are getting vaccinated and resuming normal life. But many more remain at risk until they get the vaccine, and experts are still tracking the emergence of virus variants that could pose new threats.

The Food and Drug Administration (FDA) has given emergency use authorizations (EUA) for vaccines produced by Pfizer-BioNTech, Moderna, and Johnson & Johnson. All of the authorized vaccines are highly effective at preventing severe illness and death from COVID-19, and data from the Centers for Disease Control and Prevention (CDC) suggests they also significantly prevent both symptomatic and asymptomatic infection. 

[Visit the Yale Medicine Vaccine Content Center for more stories about COVID-19 vaccines.]

In mid-May, the CDC relaxed its prevention guidelines to allow fully vaccinated Americans to resume activities they did prior to the pandemic, allowing them to gather indoors or outdoors without wearing masks or practicing social distancing (although there are still some exceptions).

SARS-CoV-2 is a virus that scientists haven’t seen before. Like other viruses, it is believed to have started in animals and spread to humans. Animal-to-person spread was suspected after the initial outbreak in December 2019 among people who had a link to a large seafood and live animal market in Wuhan, China. By January 2020, clusters of cases of a mysterious pneumonia were being reported in Wuhan, and in the following weeks person-to-person spread of the virus was reported around the world. In early March of that year, the World Health Organization (WHO) declared COVID-19 a pandemic—a disease outbreak occurring over a wide geographic area and affecting an exceptionally high proportion of the population.

Viruses are known to change constantly, and by the end of 2020, multiple COVID-19 variants were emerging. Scientists are working to learn more about these variants and their spread, and how they could affect the severity of illness in people who get the virus. In early 2021, a highly contagious variant called Delta had surfaced in India and is now the dominant strain in the United States. Early studies have shown that the vaccines provide protection against Delta, but anyone who is unvaccinated and not practicing prevention strategies is at risk for infection.

Scientists and public health officials also continue to work as quickly as possible to find more answers to key questions about how the disease affects the body and why some cases are more severe than others, and identify the best treatments for COVID-19.  

Below is a list of five things you should know about the coronavirus outbreak.

1. What we know about COVID-19 has changed rapidly

The number of people infected by the disease continues to change every day. While the impact of the disease varies by location, there are more than 193.7 million confirmed cases of people with COVID-19 around the globe and more than 4.1 million people have died from the disease, according to the WHO. (While some news sources report different numbers, the WHO provides official counts of confirmed cases once a day.)

The Centers for Disease Control and Prevention (CDC) provides a rough picture of the outbreak in the U.S. here, currently putting the total confirmed and probable cases at more than 34.3 million and estimating more than 608,400 deaths. (If there are any discrepancies, data provided by state public health departments should be considered the most up to date, according to the agency). The CDC also reports that 69% of adults have had at least one vaccination shot.  

The term coronavirus includes a family of seven known viruses that cause respiratory tract illnesses that range from the common cold to such potentially deadly illnesses as severe acute respiratory syndrome (SARS), which killed almost 800 people during an epidemic that occurred in 2002 and 2003. COVID-19 is the first pandemic known to be caused by the emergence of a new coronavirus—novel influenza viruses caused four pandemics in the last century, which is why the response to the new disease is being adapted from existing guidance developed in anticipation of an influenza pandemic.

According to the CDC, reported COVID-19 illnesses have ranged from mild (with no reported symptoms in some cases) to severe to the point of requiring hospitalization, intensive care, and/or a ventilator. In some cases, COVID-19 illnesses can lead to death. While people of all ages can be infected, the risk for complications increases with age. So people in their 50s, for instance, are at higher risk for severe illness than those in their 40s, and people ages 85 and older are at the greatest risk. People living in a nursing home or long-term care facility, and people of all ages with underlying health conditions (such as diabetes, heart disease, lung disease, and obesity) also are at high risk for serious illness.

COVID-19 also has led to serious illness and even death in younger and middle-aged adults who are otherwise healthy. While most children have mild or no symptoms, some have gotten severely ill. As with adults, even if children have no symptoms, they can spread the virus to others.

While most people recover in a matter of weeks, some experience post-COVID conditions known as "long COVID," which can appear weeks after infection and can include a range of new, returning, or ongoing health problems. These range from fatigue and muscle pain to—in extreme cases—autoimmune conditions and multisystem inflammatory syndrome, a condition where different body parts become swollen. Even people who had mild symptoms or no symptoms at all when they were infected can have post-COVID conditions.

It helps that experts have a better idea now about how the virus is transmitted from one person to another. According to the CDC, COVID-19 is spread in three ways: by breathing in air when close to an infected person who is exhaling small droplets and particles that contain the virus; having these droplets and particles land on the eyes, nose, or mouth; or touching the eyes, nose, and mouth with hands that have the virus on them. In general, the CDC says, the more closely you interact with others and the longer that interaction, the higher the risk of COVID-19 spread, and indoor spaces are more risky than outdoor spaces.

In addition, droplets can land on surfaces, and people may get the virus by touching those surfaces, although, according to the CDC, this is not thought to be the main way COVID-19 spreads.

Experts also have more to learn about the new vaccines. While early data show they may help prevent people from spreading COVID-19, researchers are still studying this. There is also more to learn about how long the vaccines can protect people, and whether booster shots will be needed to extend immunity or further protect against a variant of the virus.

2. Strict measures are critical for slowing the spread of the disease

Near the beginning of the pandemic, public health experts directed their efforts toward "flattening the curve." If you mapped the number of COVID-19 cases over time, the expectation was that it would peak at some point—on a graph this peak would mirror a surge in patients (which could overwhelm hospitals and health care providers). Flattening the curve would mean there would be fewer patients during that period, and hospitals would be better able to manage the demands of patients who are sick with COVID-19 and other illnesses.

But last November/December as winter approached, a steady increase in cases in the U.S. was becoming what some described as a third wave (or, maybe, a third peak), if not a continuation of a single wave that started in the spring and never stopped. As cold weather drove more people indoors, many government officials around the country halted some of the plans they had to reopen, implementing new restrictions that included curfews, limiting the number of people who could gather indoors, and establishing mask mandates.

But in 2021, the picture looks more hopeful as more people are vaccinated. The idea is that if enough people are protected either because they have had the disease or they’ve been vaccinated, herd immunity will start to protect even those people who have not been infected. While the timeline for herd (or population) immunity is still uncertain, researchers  believe we will likely not reach it any time soon. Experts are also concerned about Delta—while experts say the vaccines should protect most vaccinated people, those who are unvaccinated are at elevated risk for infection by the variant, which could affect the overall progress. 

3. Infection prevention is key

Now that everyone in the United States who is 16 and older is eligible to be vaccinated (or 12 and older for the Pfizer vaccine), the CDC is working with partners across the country to make sure everyone has the information they need and ensure that cost is not a barrier. (Researchers are still testing the vaccines in clinical trials for children, and Moderna and Johnson and & Johnson aren’t authorized to administer vaccines to adolescents younger than 16 at this time.) Information on where to get the vaccine, including which sites have doses available, is available through a CDC tool called VaccineFinder. Millions of people are still waiting for a vaccine, and the government is working to keep up with the demand.

There are other things you can and should continue to do to protect yourself. “The best thing you can do at this point is take care of yourself the way you would to prevent yourself from getting the flu,” says Yale Medicine infectious diseases specialist Joseph Vinetz, MD. “You know you can get the flu when people sneeze and cough on you, or when you touch a doorknob. Washing hands—especially before eating and touching your face, and after going to the bathroom—and avoiding other people who have flu-like symptoms are the best strategies at this point.” 

Studies have shown that a significant portion of people with COVID-19 have no symptoms or have symptoms so mild (like loss of smell) they may go undetected. Even those who eventually develop symptoms can transmit the virus to others before showing symptoms.

For those reasons, the CDC recommends the following preventive actions for anyone who has not been vaccinated:

  • Wash hands with soap and water for at least 20 seconds. Dry them thoroughly with an air dryer or clean towel. If soap isn’t available, use a hand sanitizer with at least 60% alcohol.
  • Stay home if you’re sick.
  • Avoid touching nose, eyes, and mouth. Use a tissue to cover a cough or sneeze, then dispose of it in the trash.
  • Wear a mask that fits snuggly over your nose, mouth and chin. The CDC specifies choosing a cloth mask that has multiple layers of fabric or one disposable mask worn underneath a cloth mask (the second mask should push the edges of the inner mask against your face). 
  • Keep about 6 feet between yourself and others (and know there have been cases of transmission between people farther than 6 feet apart, most commonly when there is prolonged exposure in an enclosed space without adequate ventilation, where an infectious person has exhaled the virus while engaged in some form of physical exertion or has raised their voice [in shouting or singing]). The CDC advises avoiding nonessential indoor spaces and crowded outdoor settings. A mask is not a substitute for social distancing.
  • Use a household wipe or spray to disinfect doorknobs, light switches, desks, keyboards, sinks, toilets, cell phones, and other objects and surfaces that are frequently touched.
  • Create a household plan of action in case someone in your house gets sick with COVID-19. You should talk with people who need to be included in your plan, plan ways to care for those who might be at greater risk for serious complications, get to know your neighbors, and make sure you and your family have a plan for caring for a sick person. This includes planning a way to separate a family member who gets sick from those who are healthy, if the need arises.
  • Plan visits with friends and family outdoors if possible. If you must visit them indoors, make sure the space can accommodate social distancing, and open doors and windows to make sure the space is well-ventilated. The CDC also recommends avoiding travel.

If you are fully vaccinated (two weeks past your second Pfizer or Moderna shot, or single Johnson & Johnson shot): CDC recommendations allow for resuming most activities without wearing a mask or social distancing either indoors or outdoors, except where required by federal, state, local, tribal, or territorial laws, rules, and regulations. This now includes camp programs where everyone is fully vaccinated prior to the start of camp.

However, local rules may vary, and fully vaccinated people must follow local business and workplace guidance, and take precautions as directed in health care settings. They must still wear masks on buses, trains, planes, and other forms of public transportation, and in U.S. transportation hubs such as airports and train stations; when visiting a doctor, hospital, or nursing home; or when in a prison, jail, or homeless shelter. Doctors are still learning about how well vaccines protect people with weakened immune systems, including those who take immunosuppressive medications, so people in that category should talk to their health care provider and may need to keep taking precautions.

More details about prevention for people who have been vaccinated can be found on the CDC website.

4. Experts are working rapidly to find solutions

In the U.S., widely available testing is important in understanding the true infection and mortality rates of COVID-19. While health providers across the country are using a variety of tests—and still learning about the most accurate approach—two kinds of tests are important to know about: viral tests help diagnose a current infection and antibody tests can tell if you’ve had a previous one. Health care providers and state and local health departments make determinations about who should be tested.

Meanwhile, scientists continue to study the virus closely. In addition to the vaccines that are now available in the U.S. and other countries, multiple vaccines are being studied. What’s more, companies that have produced vaccines are looking at whether they might need to tweak them to better protect against new mutations of the virus, as scientists continue to study how those mutations are affecting the rate of contagion and their potential for causing severe disease.

Doctors are also refining their approaches to treating COVID-19. The antiviral drug remdesivir, is the first and only drug to receive full FDA approval for patients ages 12 and older after some evidence showed it could reduce the number of days spent in the hospital. Studies on dexamethasone, a widely available corticosteroid (or steroid), have shown a link between the drug and a reduction of deaths from COVID-19 by a third for patients with “severe and critical” cases of COVID-19. Yale and other medical centers now have special clinics to treat patients with long-COVID symptoms.

5. If you feel ill, here's what you should do

Everyone should watch out for symptoms of COVID-19, whether or not they are fully vaccinated. Anyone who thinks they have been exposed should get tested and stay home and away from others. Symptoms can appear anywhere between 2 to 14 days after exposure. According to the CDC, symptoms may include: 

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

This list does not include all possible symptoms. The CDC will continue to update its symptoms list as it learns more about COVID-19.

You should call your medical provider for advice if you experience these symptoms, especially if you have been in close contact with a person known to have COVID-19 or live in an area with ongoing spread of the disease. The CDC has a Coronavirus Self-Checker that may help you determine whether you should seek help.

Most people will have a mild illness and can recover at home without medical care. Seek medical attention immediately if you or a loved one is at home and experiencing emergency warning signs, including difficulty breathing, persistent pain or pressure in the chest, new confusion, inability to stay awake, or bluish lips or face. This list is not inclusive, so consult your medical provider if you notice other concerning symptoms. 

Yale New Haven Health offers a call center for patients and people in the community who have questions about COVID-19 at 833-ASK-YNHH (833-275-9644).

Be aware of the information and resources that are available to you

Because knowledge about the new virus is evolving rapidly, you can expect information and recommendations to change frequently. Threats like COVID-19 can lead to the circulation of misinformation, so it’s important to trust information only from reputable health organizations and sources such as the CDC and the WHO. “The public health infrastructure in the U.S. is a critical resource for leading the federal, state, and local response,” Dr. Martinello says.

Yale Medicine doctors are advising anyone who has concerns about COVID-19 exposure or symptoms to call their primary care doctor for instructions. Doctors at Yale Medicine and Yale New Haven Health (YNHH) also encourage all patients to sign up for MyChart, a secure online portal that allows patients to manage and receive information about their health, and enables telehealth visits (by phone or video). If you are looking for a testing site, YNHH can help you find one that meets your needs and schedule.

The outbreak has been stressful for everyone, and this can have serious impacts on mental health. If you, or someone you care about, are feeling overwhelmed with emotions like sadness, depression, or anxiety, or feel like you want to harm yourself or others, call 911, or the Substance Abuse and Mental Health Administration’s Disaster Distress Helpline: 1-800-985-5990 or text TalkWithUs to 66746. (TTY 1-800-846-8517). You can call the National Domestic Violence Hotline at 1-800-799-7233 (TTY: 1-800-787-3224.)

Click here to learn more about Yale’s research efforts and response to COVID-19.