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.

What is COVID-19 Reinfection?

What is COVID-19 Reinfection?
Updated Mar. 15, 2023

This information is intended for a general audience.

Reinfection with the virus that causes COVID-19 occurs when you are infected, recover, and then get infected again. You can be reinfected multiple times.

Reinfections are most often mild, but severe illness can occur. If you are reinfected, you can also spread the virus to others. Staying up to date with COVID-19 vaccine and treating COVID-19 illness within a few days of when symptoms start decreases your risk of experiencing severe illness.

Once you have had COVID-19, your immune system responds in several ways. This immune response can protect you against another infection for several months, but this protection decreases over time. People with weakened immune systems who get an infection may have a limited immune response or none at all. Protection against severe COVID-19 illness generally lasts longer than protection against infection. This means even if you get infected again, your immune response will help protect you from severe illness and hospitalization.

As the virus evolves, new variants with the ability to evade your existing immunity can appear. This can increase your risk of reinfection. Reinfection can occur as early as several weeks after a previous infection, although this is rare.

COVID-19 Testing for People with a Recent History of Infection

Interpreting test results in the first 90 days after a previous infection (that is, reinfection) can be challenging. CDC has developed testing guidance explaining which type of test you should take under different circumstances.

If you have tested positive for COVID-19 within the past 90 days and are testing for a possible new infection:

  • Use an antigen test.
  • Consult a healthcare provider if you have any questions or concerns.

Protecting Yourself and Others – What You Can Do

If you were exposed to the virus that causes COVID-19, you should follow exposure guidance, regardless of your vaccination status or if you have had a previous infection. For those who have previously been infected, vaccination offers added protection, especially against reinfection leading to hospitalization. CDC recommends that people ages 6 months and older, including those with previous infections, stay up to date with COVID-19 vaccines.

Regardless of your vaccination status or if you have had a previous infection:

What CDC is doing

We continue to learn more about reinfections, especially as new SARS-CoV-2 variants emerge. CDC is working with partners and using data to better understand reinfections, including:

  • Who is at higher risk of reinfection, especially reinfections that lead to hospitalization
  • How soon reinfections occur after a previous infection
  • How severe reinfections are compared to initial infections
  • How reinfections are associated with Long COVID