Coronaviruses: Strains, Symptoms, and Prevention
Author: Disabled World (DW)
Updated/Revised Date: 2 Nov 2026
Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics
Synopsis
An overview of human coronaviruses, including the seven known strains such as SARS, MERS, and COVID-19, plus how they spread and ways to prevent infection.
At a Glance
- 1 - Dromedary camels are the main animal reservoir of MERS-CoV.
- 2 - WHO declared COVID-19 a pandemic on March 11, 2020, and ended the global health emergency on May 5, 2023.
- 3 - The 2002 to 2003 SARS outbreak caused 8,098 probable cases and 774 deaths, with no known infections since 2004.
- 4 - Over 2,600 laboratory-confirmed MERS cases have been reported to WHO since 2012, and about 37% of reported patients died.
Topic Definition
- Coronaviruses
Coronaviruses are a large family of viruses named for the crown-like spikes that stud their outer surface, and they are grouped into four main types known as Alpha, Beta, Gamma, and Delta. In people they most often cause mild to moderate upper respiratory illnesses like the common cold, but some strains have proven far more dangerous, including the viruses behind severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and coronavirus disease 2019 (COVID-19). Seven strains are currently known to infect humans, and several of them, such as SARS, MERS, and COVID-19, originally circulated in animals before evolving to spread from person to person. They carry a protein called a replicase in their genome that lets the RNA virus copy itself using the host cell's own machinery, and they spread mainly through coughing, sneezing, close personal contact, and touching contaminated surfaces.
Overview
Coronaviruses are a large family of viruses that can cause illnesses ranging from the common cold to severe respiratory disease. Seven coronaviruses are known to infect people. Four of them, 229E, NL63, OC43, and HKU1, circulate around the world all the time and usually cause mild to moderate colds. Three have caused far more severe disease: SARS coronavirus (SARS-CoV), which emerged in November 2002 and caused severe acute respiratory syndrome (SARS); MERS coronavirus (MERS-CoV), first identified in 2012 and the cause of Middle East respiratory syndrome (MERS); and SARS-CoV-2, which emerged in 2019 and causes coronavirus disease 2019 (COVID-19).
Coronaviruses are named for the crown-like spikes on their surface. Many animals carry their own coronaviruses, and SARS, MERS, and COVID-19 are all diseases that passed to people from animals [World Health Organization, 2025b].
The Seven Human Coronaviruses
- Human coronavirus 229E (alpha coronavirus): one of the viruses that cause the common cold. It can also cause more serious illness such as pneumonia and bronchiolitis.
- Human coronavirus NL63 (alpha coronavirus): identified in late 2004 in the Netherlands and found worldwide. It causes mild to moderate upper respiratory infections and can also cause croup, bronchiolitis, and lower respiratory tract infections.
- Human coronavirus OC43 (beta coronavirus): along with 229E, a common cause of colds. Both can cause severe lower respiratory tract infections, including pneumonia, in infants, older adults, and people with weakened immune systems, such as those having chemotherapy or living with HIV.
- Human coronavirus HKU1 (beta coronavirus): first identified in January 2005 in a 71-year-old man in Hong Kong who had pneumonia after a trip to Shenzhen, China.
- Middle East Respiratory Syndrome Coronavirus (MERS-CoV, beta coronavirus): first identified in Saudi Arabia and Jordan in 2012.
- SARS-CoV (beta coronavirus): first recognized in China in November 2002. It caused a worldwide outbreak in 2002 and 2003 with 8,098 probable cases, including 774 deaths, and no cases have been reported anywhere in the world since 2004.
- SARS-CoV-2 (beta coronavirus): the virus that causes COVID-19, first identified in Wuhan, China, in December 2019.
Common human coronaviruses can sometimes cause lower respiratory tract illnesses, such as pneumonia or bronchitis. This is more common in people with heart or lung disease, people with weakened immune systems, infants, and older adults.
MERS
Dromedary camels are the main reservoir of MERS-CoV. The virus passes from camels to people and can then spread between people in close contact, leading to outbreaks in hospitals and households. Typical symptoms are fever, cough, and shortness of breath, often leading to pneumonia. Since 2012, over 2,600 laboratory-confirmed cases have been reported to WHO from 27 countries, most of them from Saudi Arabia, and about 37% of reported patients have died, though this is likely an overestimate because mild cases may be missed. There is no specific treatment or licensed vaccine for MERS, and medical care is supportive [World Health Organization, 2025b]. Only two patients in the United States have ever tested positive for MERS-CoV, both in May 2014.
COVID-19
SARS-CoV-2 spreads through the air in infectious respiratory particles released when an infected person breathes, talks, coughs, or sneezes, and it spreads most easily in close contact or shared indoor spaces. WHO declared COVID-19 a pandemic on March 11, 2020, and ended the global health emergency on May 5, 2023. Nearly 780 million cases and more than 7.1 million deaths have been reported to WHO since December 2019, and the true numbers are thought to be higher [World Health Organization, 2025a].
COVID-19 vaccines continue to give strong protection against severe illness and death, and WHO recommends vaccination based on each person's risk. Antiviral medicines such as nirmatrelvir with ritonavir (Paxlovid) and remdesivir are used to treat COVID-19 in people at risk of severe disease.
How Human Coronaviruses Spread
- Through the air, in droplets and particles released when an infected person coughs, sneezes, talks, or breathes
- Through close personal contact, such as touching or shaking hands
- By touching a contaminated surface and then touching the mouth, nose, or eyes before washing the hands
Treatment and Prevention
There are no specific treatments or vaccines for the common cold coronaviruses, and most people recover on their own. To ease symptoms:
- Take pain and fever medicines (do not give aspirin to children).
- Drink plenty of liquids, stay home, and rest.
- Use a room humidifier or take a hot shower to help ease a sore throat and cough.
To lower the risk of infection and protect others:
- Wash your hands often with soap and water for at least 20 seconds.
- Avoid touching your eyes, nose, or mouth with unwashed hands.
- Avoid close contact with people who are sick, and stay home while you are sick.
- Cover your mouth and nose with a tissue when you cough or sneeze, throw the tissue in the trash, and wash your hands.
- Clean and disinfect objects and surfaces that are touched often.
The 2019 to 2020 Wuhan Outbreak
The COVID-19 pandemic began as a cluster of pneumonia cases with no clear cause in Wuhan, China, in December 2019, many of them linked to the Huanan Seafood Wholesale Market, where live animals were sold. On January 9, 2020, WHO reported that Chinese authorities had identified a new coronavirus. An early report suggesting snakes as the source was quickly disputed, and bats are considered the most likely original source of the virus. On January 23, 2020, Wuhan was placed under quarantine, and public transport in and out of the city was suspended.
Frequently Asked Questions
What is the difference between a cold caused by a coronavirus and COVID-19?
Common cold coronaviruses usually cause mild upper respiratory symptoms, while COVID-19 is caused by SARS-CoV-2 and can range from no symptoms to severe respiratory illness and complications.
How long do coronaviruses survive on surfaces?
Survival time varies by virus, surface, and conditions, ranging from hours to several days, which is why regular cleaning and hand washing help reduce the risk of transmission.
Can pets and animals carry coronaviruses?
Many animals carry their own coronaviruses, and some strains have jumped from animals to humans, though most animal coronaviruses do not infect people.
Are there vaccines for any human coronaviruses?
Vaccines have been developed for COVID-19, but there are no widely available vaccines for the common cold coronaviruses or for MERS and SARS.
How can I tell if my respiratory illness is a coronavirus?
Because symptoms overlap with other respiratory infections, only laboratory testing can confirm a specific coronavirus, so consult a healthcare provider if you are concerned.
Who is most at risk of severe illness from coronaviruses?
Infants, older adults, and people with weakened immune systems or heart and lung conditions face a higher risk of severe lower respiratory complications.
How long does it take to recover from a coronavirus infection?
Mild common cold coronavirus infections often clear within a week or two, while more severe illnesses from strains like MERS or COVID-19 can require much longer recovery.
What is long COVID?
Long COVID is a range of symptoms, such as fatigue, brain fog, and shortness of breath, that last for months after a COVID-19 infection. It can be disabling and may be covered as a disability under the ADA when it substantially limits daily activities.
References
- World Health Organization. (2025a). Coronavirus disease (COVID-19) [Fact sheet].
- World Health Organization. (2025b). Middle East respiratory syndrome coronavirus (MERS-CoV) [Fact sheet].
Curated and edited by Ian C. Langtree, Founder and Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team. Last updated: