Updated on January 22, 2021.
Two COVID-19 vaccines are available for emergency use in the United States and Americans have begun either lining up or waiting for their turn to receive their shots.
Nearly 38 million doses of the vaccines have been distributed across the United States as of January 21, and more than 15 million people have received their first shot, according to the Centers for Disease Control and Prevention (CDC).
The first vaccine granted Emergency Use Authorization by the U.S. Food and Drug Administration and approved by the CDC, known as BNT162b2, is a two-dose mRNA vaccine developed by Pfizer and the German drugmaker, BioNTech. Pfizer said it was 95 percent effective in clinical trials. Americans began receiving this vaccine on December 14, 2020—nine months after the World Health Organization declared the COVID-19 outbreak a pandemic.
About a week later, the FDA granted EUA to another COVID-19 vaccine, known as mRNA-1273. This second vaccine was developed by Moderna. In clinical trials, the two-dose vaccine was shown to be 94.1 percent effective against COVID-19 and 100 percent effective against severe COVID-19.
Both companies say that the efficacy of their vaccines is similar across age, race, ethnicity, and gender groups—although the vaccines haven’t yet been tested in children.
What we’ve learned
Since the coronavirus infection was first reported in late 2019, COVID-19 has affected millions of people around the world—physically, emotionally and financially. The previously unimaginable global crisis left many people wondering: Where did this disease come from? What does it do to the body and how do people know if they are infected? Are the vaccines safe and effective?
The origins of COVID-19
The coronavirus that causes COVID-19 was identified in early January 2020 in Wuhan, China after doctors in the region reported many cases of “pneumonia with an unknown cause.” About a month later, scientists officially named the newly identified virus SARS-CoV-2.
SARS-CoV-2 is just one of seven coronaviruses known to cause respiratory symptoms in people. Four of them cause mild infections but three have led to serious illnesses, including Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS).
These viruses usually circulate among animals, particularly camels as well as cats or bats. On rare occasions, animal coronaviruses can mutate and spread to people.
The outbreak in China was initially linked to a large seafood and animal market in the Hubei province. Scientists believe SARS-CoV-2 originated in bats. There is also speculation that the virus then spread to pangolins before infecting humans.
Warning signs of infection
People infected with COVID-19 have developed a range of symptoms associated with a respiratory infection.
The most commonly reported symptoms include:
- Fever
- Dry or productive cough
- Fatigue
- Loss of sense of smell or taste
- Shortness of breath
- Sore throat
- Headache
- Muscle and joint pain
- Chills
Less commonly reported symptoms include nausea or vomiting and diarrhea.
About 15 percent of cases result in severe illness and complications, including pneumonia and trouble breathing. Another 5 percent of cases are critical, leading to more serious issues, including respiratory failure, septic shock and organ failure.
Researchers are still investigating how the coronavirus affects the body, but symptoms tend to develop, on average, about five days after exposure. In some cases, the SARS-CoV-2 incubation period—the amount of time between exposure to an infection and when symptoms begin—may be even longer than 14 days.
Some people have also tested positive for COVID-19 up to 3 days before they developed symptoms while others have tested positive even though they never developed any symptoms at all. This supports the idea that people can be infectious and shed the virus even before they realize they are sick. This has made controlling the pandemic much more challenging.
Those at greatest risk
Anyone can develop COVID-19 but older people are among those at highest risk for serious disease. The immune system weakens with age and older people are more likely to have underlying health issues, which also increase the risk for COVID-19-related complications.
Those with a weakened immune system or chronic conditions, such as high blood pressure, severe obesity, diabetes, heart disease, chronic lung disease or cancer, are more likely to develop severe cases of COVID-19 and related complications.
Keep in mind, even otherwise healthy younger adults can also develop a more serious infection that requires hospitalization. The risk of dying, however, is much greater for older people.
Researchers are still working to understand why children seem to be at lower risk for severe COVID-19. Some reasons may include the fact that they have stronger innate immune systems (non-specific defenses that jump into action when introduced to a new germ) than adults who rely more heavily on their acquired immune response, which is developed over time after exposure to infections.
There is also evidence that younger kids tend to have reduced expression of a cell surface enzyme, known as ACE2 (angiotensin-converting enzyme 2), which the coronavirus uses to invade cells in the lining of the nose.
How the infection spreads
COVID-19 spreads mainly through contaminated respiratory droplets that are emitted when infected people cough or sneeze and possibly when they breathe or speak.
When these droplets escape the body they may land in a nearby person’s mouth, nose or eyes. They can travel about six feet before settling on a nearby surface. If you touch a contaminated surface then touch your mouth, nose or eyes, you can also become infected.
It is not yet clear how long SARS-CoV-2 survives on surfaces, but early evidence suggests it may persist for up to several days, depending on the type of surface and other variables, like temperature and humidity.
Under certain conditions, the coronavirus can spread through the air. Airborne spread involves aerosols—particles even smaller than respiratory droplets that may waft and linger in the air.
This is more likely to occur indoors, particularly in areas with poor ventilation or where people are singing or exercising.
Having close contact with an infected person is risky—even if those encounters are brief.
The CDC defines “close contact” as being within 6 feet of those with COVID-19 for a total of 15 minutes or more over a 24-hour period, beginning two days before they test positive or develop symptoms.
Bottom line: COVID-19 spreads very easily—even more efficiently than the flu.
Diagnosing COVID-19
When experts talk about testing for the coronaivirus, they’re really referring to two different categories: diagnostic tests and antibody tests.
There are two types of diagnostic tests being used: a polymerase chain reaction (PCR) test and an antigen test. Both of these tests check for the coronavirus itself, using saliva or a respiratory sample collected by nasal or throat swab. The results are intended to reveal whether or not you’re currently infected.
PCR tests look for evidence of genetic material from the virus. Antigen tests are designed to detect fragments of proteins found on or inside the virus.
PCR tests are typically more accurate than antigen tests but take longer—hours or days—to process. Antigen tests, on the other hand, can provide results within minutes. Although positive antigen test results are very reliable, these tests tend to miss more cases than PCR tests. So a negative antigen test result may need to be confirmed with a PCR test.
Unlike these two types of diagnostic tests, an antibody test doesn’t tell you if you have the disease right now. It helps determine if you’ve been infected in the past.
Rather than testing respiratory specimens collected by swabs, antibody tests (also called serology tests) check your blood for antibodies to SARS-CoV-2, which would indicate a past encounter with the virus.
Recovery doesn’t guarantee immunity
You are likely immune for at least some length of time after recovering from COVID-19, but it’s unclear how long you’ll be protected.
Researchers are still investigating how long antibodies last. People who’ve had COVID-19 may continue to produce protective antibodies against certain parts of the virus for at least three to four months. Some evidence suggests antibodies may last eight months.
People who’ve had COVID-19 may have low levels of coronavirus RNA in their bodies for up to three months, the CDC reports. It’s not yet known if those who’ve recovered—but still have detectable levels of viral RNA—are infectious and pose a risk to others.
It’s also possible to get COVID more than once. Reinfection in people who test negative after a recent infection is rare. But the risk is not zero.
Complicating matters, reinfections may be mild. Some people may not develop any symptoms at all and not realize that they are positive for COVID-19. Scientists are also still working to understand how the newly identified strains of the coronavirus may affect the rate of reinfections.
Treating COVID-19
In most cases, people with mild or moderate COVID-19 can manage their symptoms and recover at home. Supportive care, such as over-the-counter pain relievers, getting plenty of rest and drinking fluids, can help.
Those with more serious cases who require hospitalization may need more specialized care, including IV fluids, medications, oxygen support or dialysis.
The FDA approved the antiviral drug, Remdesivir (Veklury), for the treatment of COVID-19 that results in hospitalization. The drug, made by Gilead Sciences, is the only approved therapy for the disease in the United States.
The FDA, however, granted emergency use for two monoclonal antibody treatments, laboratory-made versions of natural antibodies against the coronavirus. The drugs, called casirivimab and imdevimab, are authorized for use in people age 12-years and older who weigh at least 88lbs and are at high risk for severe COVID-19.
Corticosteroids, such as dexamethasone or hydrocortisone, which are used to suppress the immune system and ease inflammation may also be used to treat patients with severe COVID-19.
Precautions are still necessary
One of the best ways to protect yourself against COVID-19 is to be immunized as soon as the vaccine is available to you.
Vaccines can help prevent someone who has been exposed to the coronavirus from getting sick or developing symptoms. But it’s still unclear if the vaccines block transmission or prevent someone from carrying the virus and silently spreading it to others.
Research on the vaccines and their ability to block transmission is ongoing.
Additionally, the rollout of the vaccines will take time. It will be many months before everyone who wants to be vaccinated receives their shots.
Moreover, the Pfizer vaccine was shown to be 95 percent effective in clinical trials. The Moderna vaccine was found to be 94.1 percent effective. This means that a small percentage of people may not be protected by them.
Until enough of the population is vaccinated and immune to the coronavirus, preventative measures—masks, social distancing, avoiding crowded indoor spaces with poor ventilation and diligent hand hygiene—will still be necessary.
How to protect yourself and others
One of the most effective ways to avoid exposure to COVID-19 is to limit your trips to public places and the amount of time you spend there. If you do leave home, practice social distancing—keep at least six feet of space between you and others.
Be sure to wear a face mask or cloth covering over your mouth and nose when out in public or around others—whether you have symptoms or not.
Other ways to help prevent the spread of COVID-19:
- Wash your hands well and often with soap and water for at least 20 seconds each time. If you don’t have access to soap and water, use a hand sanitizer than contains at least 60 percent alcohol.
- Avoid touching any part of your face, including your eyes, nose or mouth with unwashed hands.
- Cover your cough or sneeze with an unused tissue, then throw the tissue in the trash. If you don’t have a tissue, use your upper sleeve or elbow—not your hands.
- Clean and disinfect commonly used objects and surfaces you come into contact with throughout your day, such as computer keyboards, cell phones, doorknobs, faucets and bathroom fixtures with household cleaning sprays or wipes. Effective products include diluted household bleach solutions or cleaners with at least 70 percent alcohol as well as most common EPA-registered household disinfectants.
Avoid people with suspected or confirmed infections
If you think you’re infected
If you believe you were exposed to COVID-19 or if you, or someone in your home, has symptoms consistent with a respiratory infection, take immediate steps to isolate yourself to avoid spreading your illness to others. This means keeping distance between yourself and the other people in your home.
Call your healthcare provider (HCP) for instructions. Do not go to your doctor’s office without calling ahead first and letting the office staff know that you suspect you’ve been exposed to COVID-19.
Your doctor should determine if you can be treated at home, and also determine if you should be tested for the coronavirus.
If you develop serious warning signs of COVID-19, however, you need to seek immediate medical attention. These red flags may include:
- Difficulty breathing or shortness of breath
- Persistent pain or pressure in the chest
- Feeling confused
- Bluish lips or face
Call 911 and let the operator know that you have or think you may have COVID-19. If you have a medical mask, put it on before help arrives.
