[Originally published: Jan. 29, 2020. Updated: Nov. 23, 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 got vaccines and started to resume a more normal life. But many more remain at risk until they get vaccinated, and experts are still tracking the emergence of virus variants that could pose new threats.
In the U.S., three vaccines are being administered from Pfizer-BioNTech, Moderna, and Johnson & Johnson for adults 18 and older. Only Pfizer-BioNTech is authorized for children and teenagers ages 5-15; it has full approval for ages 16 and older.
Now that the highly contagious Delta variant still dominant in the U.S., worry continues and the CDC has kept stronger guidelines for wearing masks for prevention.
Scientists and public health officials 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.
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 256.9 million confirmed cases of people with COVID-19 around the globe and more than 5.1 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 CDC provides a rough picture of the outbreak in the U.S. here, currently putting the total confirmed and probable cases at more than 47.6 million and estimating more than 770,800 deaths. The CDC also reports that 73.9% of children and adults ages 5 and older in the U.S. have had at least one vaccination shot and 62.9% of people in the same age group is fully vaccinated.
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. COVID-19 illnesses can also lead to death. While people of all ages can be infected, the risk for complications increases with age. 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 adults and children 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.
Viruses are known to change constantly, and by the end of 2020, multiple coronavirus 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. They have been studying Delta closely since it surfaced early this year in India. 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.
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. And experts are concerned that outbreaks of the Delta variant could affect overall progress.
3. Infection prevention is key
Now that all adults are eligible to be vaccinated (as well as children as young as 5 for the Pfizer-BioNTech vaccine), the CDC is working with partners across the country to make sure everyone has the information they need.
All adults 18 or older are eligible for a booster shot six months after completing their primary vaccination series if they started with Pfizer-BioNTech or Moderna—or two months after getting the J&J single-shot vaccine. A mix-and-match policy means that any of the three COVID-19 vaccines available in the U.S. can be taken as a booster shot, regardless of which vaccine a person had for their primary vaccination.
A third dose of Pfizer-BioNTech or Moderna was recommended at least 28 days after the second dose to help people with certain immunocompromising conditions reach a level of immunity they were not able to reach after two doses. In October, the CDC issued additional interim guidelines saying that moderately and severely immunocompromised people who received an mRNA vaccine, and are 18 and older, may receive a booster dose of any COVID-19 vaccine at least six months after their third dose. The CDC also recommended that anyone who got the single-shot Johnson & Johnson vaccine get an mRNA or J&J booster at least two months later.
Information on where to get the vaccine, including which sites have doses available, is available through a CDC tool called VaccineFinder.
There are other things you can and should continue to do to protect yourself. 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. 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:
- You can participate in many of activities that you did before the pandemic, but CDC recommendations advise wearing a mask indoors in public to maximize protection from the Delta variant if you are in an area of substantial or high transmission.
- You should wear a mask regardless of local transmission if you have a weakened immune system or, because of your age or an underlying medical condition, you are at increased risk for severe diseases, or if someone in your household is in that situation or is unvaccinated, according to the CDC.
If you are pregnant:
- In August, the CDC urged pregnant people to get vaccinated. Pregnant people are at an increased risk for severe illness from COVID-19 when compared to those who aren’t pregnant, as well as for increased risk for preterm birth (delivering the baby earlier than 37 weeks), and possibly other poor pregnancy outcomes, according to the CDC.
The CDC has also recommended universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status.
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.
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
- Shortness of breath or difficulty breathing
- Muscle or body aches
- New loss of taste or smell
- Sore throat
- Congestion or runny nose
- Nausea or vomiting
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.
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,” says Richard Martinello, MD, a Yale Medicine infectious diseases expert.
The pandemic 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.)