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5 Things Everyone Should Know About the Coronavirus Outbreak

BY KATHY KATELLA April 16, 2021

Strict precautions are still critical as U.S. rolls out vaccines.

[Originally published: January 29, 2020. Updated: April 15, 2021.] 

COVID-19 has upended daily life in the United States as SARS-CoV-2, the virus spreading the disease, causes new surges in infections across the country. Americans have been adjusting to strict guidelines, canceling activities, and in some areas following mandates to stay home on and off for almost a year. Now vaccines to prevent COVID-19 are bringing hope, and people who are getting vaccinated are starting to think about when they can go back to normal. Meanwhile 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 (although federal authorities have recommended halting distribution of the latter while they investigate incidents of rare blood clots in six people who received it). All of the authorized vaccines are highly effective at preventing COVID-19, especially severe illness and death.

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

“Until we’re able to vaccinate most people against COVID-19, we have to continue to do the important, albeit tedious, work of keeping ourselves safe and healthy—by wearing facial coverings, keeping our social distance, practicing good hand hygiene, and staying home when we’re sick,” says Jaimie Meyer, MD, MS, a Yale Medicine infectious disease specialist. Although recent data from the CDC suggests that the vaccines significantly prevent both symptomatic and asymptomatic infection, experts anticipate these precautions will need to continue even after many people have received the vaccine. 

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 as well as the effectiveness of the available vaccines.

Scientists and public health officials also are working 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 138.6 million confirmed cases of people with COVID-19 around the globe and more than 2.9 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 31.3 million and estimating more than 562,000 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 202 million vaccines have been administered in the U.S. 

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.

It helps that experts have a better idea now about how the virus is transmitted from one person to another. The main way COVID-19 is thought to spread is through droplets when a person who has the virus breathes, coughs, sings, sneezes, or talks, and another person inhales those droplets through the airways, mouth, nose, and lungs, according to the CDC. Evidence is growing that the droplets can stay in the air and travel beyond 6 feet indoors. 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. 

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.

In 2021, experts hope the numbers will go down 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. 

3. Infection prevention is key

As vaccines become available to more people, the CDC is working with partners across the country to make sure everyone has the information they need to be confident in deciding to get vaccinated, and ensure that cost is not a barrier. The CDC has made recommendations on when particular groups can get the vaccine, and provides information on its website for how to look up each state’s plan. (Information on where to get the vaccine, including which sites have doses available, will gradually become 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 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.”

Masks have also become a key part of the prevention strategy, since they provide a barrier that keeps respiratory droplets from spreading, protecting both the person wearing the mask and other people around the wearer, according to the CDC. 

Still, 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. In general, the more people you interact with, the more closely you interact with them, and the longer the interaction, the higher your risk of getting and spreading COVID-19, according to the CDC.

The CDC recommends the following preventive actions:

  • 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—the CDC also 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: People who are two weeks past their second Pfizer or Moderna shot, or their single Johnson & Johnson shot, should still take precautions in public places: wear a mask, maintain a 6-foot distance, avoid medium or large gatherings, and wash hands frequently. But CDC guidance now allows fully immunized Americans to travel domestically without having to show negative COVID-19 test results or quarantine (but masks are necessary when using any form of public transportation). Anyone traveling outside of the U.S. should first pay close attention to their international destination.

The CDC’s latest recommendations also allow vaccinated people to gather indoors with other fully vaccinated people without wearing masks or staying 6 feet apart. It also allows someone who is fully vaccinated to gather indoors with unvaccinated people of any age from one household without masks or staying 6 feet apart, unless those people or other people they live with are at increased risk for severe illness with COVID-19. If you are fully vaccinated and have been exposed to COVID-19 (and don’t live in a group setting), you only need to stay away from others and get tested if you have symptoms. 

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 (it is not yet known whether COVID-19 antibodies can protect from being infected again or how long protection might last). 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, there are multiple vaccines still being studied. What’s more, companies that have produced vaccines are tweaking 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. 

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

Symptoms of COVID-19 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.