Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

About COVID-19

About COVID-19
Updated May 11, 2023

What is COVID-19?

COVID-19 (coronavirus disease 2019) is a disease caused by a virus named SARS-CoV-2. It can be very contagious and spreads quickly. Over one million people have died from COVID-19 in the United States.

COVID-19 most often causes respiratory symptoms that can feel much like a cold, the flu, or pneumonia. COVID-19 may attack more than your lungs and respiratory system. Other parts of your body may also be affected by the disease. Most people with COVID-19 have mild symptoms, but some people become severely ill.

Some people including those with minor or no symptoms will develop Post-COVID Conditions – also called “Long COVID.”

How does COVID-19 spread?

COVID-19 spreads when an infected person breathes out droplets and very small particles that contain the virus. Other people can breathe in these droplets and particles, or these droplets and particles can land on their eyes, nose, or mouth. In some circumstances, these droplets may contaminate surfaces they touch.

Anyone infected with COVID-19 can spread it, even if they do NOT have symptoms.

The risk of animals spreading the virus that causes COVID-19 to people is low. The virus can spread from people to animals during close contact. People with suspected or confirmed COVID-19 should avoid contact with animals.

How COVID-19 Spreads

What are antibodies and how do they help protect me?

Antibodies are proteins your immune system makes to help fight infection and protect you from getting sick in the future. A positive antibody test result can help identify someone who has had COVID-19 in the past or has been vaccinated against COVID-19. Studies show that people who have antibodies from an infection with the virus that causes COVID-19 can improve their level of protection by getting vaccinated.

About Antibodies

What are ways to prevent COVID-19?

There are many actions you can take to help protect you, your household, and your community from COVID-19. CDC’s COVID-19 hospital admission levels help individuals and communities decide when to take action to protect yourself and others based on the latest data and information from your area.

In addition to staying up to date with COVID-19 vaccines and basic health and hygiene practices like handwashing, CDC recommends some prevention actions at all COVID-19 hospital admission levels.

How to Protect Yourself and Others

Who is at risk of severe illness from COVID-19?

Some people are more likely than others to get very sick if they get COVID-19. This includes people who are older, are immunocompromised, have certain disabilities, or have underlying health conditions. Understanding your COVID-19 risk and the risks that might affect others can help you make decisions to protect yourself and others.

What are variants of COVID-19?

Viruses are constantly changing, including the virus that causes COVID-19. These changes occur over time and can lead to new strains of the virus or variants of COVID-19 . Slowing the spread of the virus, by protecting yourself and others, can help slow new variants from developing. CDC is working with state and local public health officials to monitor the spread of all variants, including Omicron.

About Variants