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Disease information

Virus or bacteria

COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 virus, or SARS-CoV-2.

How it spreads

• Coughing
• Sneezing
• Talking or singing
• Touching contaminated surfaces and then touching your eyes, nose or mouth

The number of people that can get COVID-19 from one infected person changes due to several factors, like:

• How much virus is in the person’s saliva
• If they use masks and physical distance
• The environment (temperature, number of people, closeness, time spent, etc.)

Without safety measures, most people will infect 2 or 3 others. But, a small number of people have been found to infect dozens of others in “super-spreader events.”

Symptoms

Common symptoms

• Fever
• Dry cough
• Fatigue

Other symptoms

• Loss of taste or smell
• Nasal congestion
• Conjunctivitis (“pink eye”)
• Sore throat
• Headache
• Muscle or joint pain
• Nausea or vomiting
• Diarrhea
• Loss of appetite
• Rash or discoloration of fingers or toes

Symptoms of severe disease

• Shortness of breath or difficulty breathing
• Confusion
• Chest pain
• High fever
• Blood clots

Typical disease timeline

Symptoms appear about 6 days after exposure. They last for 1 to 2 weeks in most people. However, some people can have symptoms for up to 6 weeks. And a small number of people can have symptoms even longer (months or years).

Possible complications

• Pneumonia (infection of the lungs)
• Respiratory failure
• Acute respiratory distress syndrome (ARDS)
• Bloodstream infection and shock
• Multi-organ failure
• Children and adults can develop a rare, yet severe, inflammatory disorder weeks after infection, often referred to as multisystem inflammatory syndrome (MIS-C or MIS-A)
• Disease can be fatal

Other things to know

• Not everyone develops symptoms when they are infected.
• Infected people can spread the virus even when they do not have symptoms.
• Some people are at greater risk of getting very sick, like those:
  • Over 60 years of age
  • With high blood pressure
  • With chronic heart or lung disease
  • With diabetes
  • Who are obese
  • Who are pregnant
• Anyone can have severe COVID-19, even if they are not in a high-risk group.
• A small number of people have symptoms that last weeks to months after they recover (called “long COVID”). Symptoms vary, but can include:
  • Shortness of breath
  • On and off fevers
  • Kidney problems
  • Heart problems
  • Concentration problems (“brain fog”)

Studies are currently being done to better understand this condition. 

Vaccine information

The COVID-19 vaccine is used to prevent SARS-CoV-2 infections.

When SARS-CoV-2 emerged as a new virus in 2019, it quickly spread throughout the world. Within one year, vaccines were developed through unprecedented collaboration between governments, scientists and medical professionals. While the new vaccines were tested and approved faster than previous vaccines, safety remained a top concern and was carefully evaluated.

Vaccine type

• Nucleic acid vaccines
• Recombinant vaccines

Vaccine side effects

Common

• Pain at injection site (49 to 90 of 100 recipients)
• Redness or swelling at injection site (about 10 of 100 recipients)
• Tiredness or fatigue (31 to 68 of 100 recipients)
• Headache (25 to 63 of 100 recipients)
• Muscle aches (6 to 51 of 100 recipients)
• Fever (1 to 17 of 100 recipients)
• Chills (6 to 48 of 100 recipients)
• Joint pain (9 to 45 of 100 recipients)

Rare

• Swelling of lymph nodes under arm that received injection (3 of 1,000 Pfizer vaccine recipients; 120 to 160 of 1,000 Moderna vaccine recipients; not caused by J&J/Janssen (no longer available in the U.S.) or Novavax vaccine)

Very rare

• Thrombosis with thrombocytopenia syndrome or TTS: About 1 to 2 of 1,000,000 recipients of the J&J/Janssen COVID-19 vaccine (no longer available in the U.S.); about 4 of 1,000,000 recipients of the AstraZeneca vaccine (never used in the U.S.).
• Anaphylaxis: About 3 to 5 of 1,000,000 recipients.
• Myocarditis: About 20 per 1,000,000 recipients of the mRNA vaccine; mostly, after the second dose. Also, it may rarely follow receipt of the Novavax vaccine.

Other things to know

• Side effects most commonly occur 1 to 2 days after vaccination and last for a day or two. These side effects are seen most commonly in people less than 55 years of age. In those who receive the mRNA or recombinant vaccines, side effects occur more commonly after the second dose than the first.
• Males younger than 30 are more likely to experience myocarditis following vaccination, but the frequency of this side effect has decreased to background levels over time, meaning that the cases of myocarditis in a group of vaccine recipients is the same as that in a group of unvaccinated people with similar characteristics. Also, of note, even when this side effect was more common, rates after vaccination were less than those that occurred during infection.
• Some people have severe allergic (anaphylactic) reactions after getting the mRNA vaccine, but this has been rare. For example, out of about 2 million people who got the Pfizer vaccine, 23 had this type of reaction.
• People with allergies to any vaccine ingredients should not get the version with the ingredient; they may still be able to get a different version.
• Pregnant women who get the vaccine and develop a fever should take acetaminophen to protect their unborn babies from possible negative effects caused by fevers during pregnancy.
• People with COVID-19 should wait until they are better to get vaccinated. These people may also opt to delay their next dose until at least four months after illness for a better immune response to the vaccine.

Reasons to get the COVID-19 vaccine

• Anyone can get COVID-19. While the disease is minor for most people, we don’t know for whom it will be severe.
• Some people suffer long-lasting effects of disease. Vaccination decreases the likelihood of experiencing these lingering effects.
• Some people experience a delayed multisystem inflammatory syndrome (MIS-C or MIS-A).
• COVID-19 can be fatal.
• Unvaccinated people are a higher risk of being hospitalized, developing lingering symptoms, and spreading SARS-CoV-2 in the community (due to longer periods of viral shedding) compared with vaccinated people.
• The COVID-19 vaccine is safe.