Coronaviruses

Overview

Coronaviruses are a large family of viruses. They usually cause mild to moderate respiratory tract illnesses in humans (the common cold can cause severe diseases like pneumonia in people who are immunocompromised). However, three coronaviruses have caused more serious and fatal disease:

• SARS-CoV, which emerged in November 2002 and causes SARS
• MERS-CoV, which emerged in 2012 and causes MERS
• SARS-CoV-2, which emerged in 2019 and causes COVID-19

Related Terms: Coronaviruses are known by several related names and terms:

• Common cold (viruses: HCoV-OC43, HCoV-NE63, HCoV-HKU1, and HCoV-229E)
• Severe acute respiratory syndrome (SARS) (virus: SARS coronavirus or SARS-CoV)
• Middle East respiratory syndrome (MERS) (virus: MERS-related coronavirus or MERS-CoV)
• Coronavirus disease 2019 or COVID-19 (virus: SARS-CoV-2 or 2019-nCoV)
  • Post-acute sequelae of SARS-CoV-2 infection (PASC; also known as Long COVID)

Signs and Symptoms

Common Cold Symptoms

Symptoms of the common cold usually peak within 2-3 days of infection and may include:

• Runny or stuffy nose
• Sneezing
• Cough
• Sore throat
• Headache
• Mild body aches
• Low grade fever

COVID-19 Symptoms

COVID-19 symptoms often resemble those of a cold, the flu, or pneumonia. COVID-19 can also affect parts of the body beyond the lungs and respiratory system. Most people who get COVID-19 have a mild form of the illness and can recover at home. However, people with certain risk factors may experience serious illness.

Common symptoms of COVID-19 include:

• Fever and/or chills
• Headache
• Muscle pain or body aches
• Feeling tired or weak
• Sore throat
• Difficulty with concentration (“Brain Fog”)
• Runny or stuffy nose
• Sneezing
• Cough
• Shortness of breath or difficulty breathing
• Vomiting and diarrhea
• Change in or loss of taste or smell

Signs and symptoms can differ from person to person. Some people with COVID-19 become very sick about a week after symptoms start. They may have trouble breathing and can develop pneumonia. In severe cases, the kidneys, liver, or lungs might stop working, which could lead to death.

Many people recover from an initial acute COVID-19 illness within four weeks. Others continue to recover for four to 12 weeks or longer.

Some people develop a chronic condition called Long COVID. Symptoms of Long COVID include:

• Shortness of breath
• Extreme tiredness
• Muscle aches and weakness
• Sleep difficulties
• Trouble thinking clearly and remembering
• Headache
• Heart palpitations

These symptoms can last for weeks, months, or years.

Related Health Effects

COVID-19 can affect parts of the body beyond the lungs and respiratory system. The immune system responds to SARS-CoV-2 by causing inflammation. This can result in redness due to increased blood flow, swelling, and fever that helps kill germs. But inflammation can cause damage in the lungs or other organs of people with COVID-19. Some people have a severe immune response known as a cytokine storm, which is very serious and increases the risk of death.

Long COVID (also called long-haul COVID, post-COVID condition, chronic COVID, and post-acute sequelae of SARS-CoV-2 infection) involves a variety of symptoms that persist for more than 2-3 months after SARS-CoV-2 infection and cannot be explained by other medical conditions.

Causes and Risk Factors

Coronaviruses can spread in several ways:

• Most commonly through indirect contact with respiratory droplets from a person who is coughing or sneezing
• Surface transmission, such as touching a surface where viruses are still present minutes to hours after they landed may also spread coronaviruses

Scientists are studying why COVID-19 affects people differently. These differences likely stem from a mix of factors including genetics, how much virus someone is exposed to, and how much immunity the population has to circulating variants.

Older adults are more likely to become seriously ill from the COVID-19. People with certain health conditions are also more vulnerable. These conditions include diabetes, cardiovascular disease, and cancer.

Prevention Guidance

Getting vaccinated is the best way to prevent or lessen the severity of COVID-19. When you get vaccinated, your immune system prepares to fight off that germ. If you are exposed to it again, it recognizes the germ and destroys it. Your risk of having severe disease and Long COVID is lower if you have been vaccinated against SARS-CoV2.

Masking, proper handwashing, use of hand sanitizers, and social distancing help reduce the spread of all types of coronaviruses.

Research has not clearly shown that any dietary supplement helps prevent COVID-19.

Treatment and Management

For those at high risk of becoming seriously ill from COVID-19, treatments are available that can reduce the chances of being hospitalized or dying. Receiving treatment early, within five to seven days of initial symptoms, is critical.

If you get sick with COVID-19 and are at high risk for serious illness, talk to your doctor or other healthcare provider immediately about the best treatment options for you, even if your symptoms are mild.

Tell healthcare providers about any dietary supplements and medicines you take. Dietary supplements might interact with your medicines in the body in harmful ways.

For more information on the safety of specific dietary supplements considered for COVID-19, see Dietary Supplements in the Time of COVID-19.

Antiviral Treatments

Antiviral medications like Nirmatrelvir, Molnupiravir, Paxlovid and Remdesivir help stop the virus from multiplying in your body. This helps reduce recovery time.

Host-Directed Treatments

Host-directed treatments suppress inflammation that the human body produces a part of the defenses against an invading germ. These therapies, which include a corticosteroid (dexamethasone) or a kinase inhibitor (Baricitinib), are given to certain people hospitalized with COVID-19.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on COVID-19.

Community Support

• NIH Community Engagement Alliance (CEAL)
• U.S. Centers for Disease Control and Prevention Covid information page

Note: This resource list is for informational purposes only. It is not comprehensive, and an organization’s inclusion does not constitute an endorsement by NIH.  

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

NIH investigators are studying: 

• How viruses like SARS-CoV-2 and MERS cause disease and how the immune system responds to infection or vaccination.
• The basic characteristics of SARS-CoV-2 to find better ways to detect, prevent, and treat COVID-19. This includes studies to understand the immune response to the virus.
• Virus genetics and how SARS-CoV-2 variants emerge. 
• The impact of SARS-CoV-2 variants on transmission and disease, and their potential to escape immunity.

Some people have specific genomic variants that can influence how a virus interacts with their body. Researchers continue to study these mechanisms, including the relationship between the level of viral infection and specific variants.
NIH laboratories and NIH-supported scientists are working to develop universal coronavirus vaccines, which aim to protect against multiple types of coronaviruses and viral variants. A growing body of evidence strongly suggests that novel coronaviruses will continue to infect bats and other animal reservoirs and potentially emerge to pose a pandemic threat to humans.

NIH also continues to support research into Long COVID biology and potential treatments.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.