Several precautions can reduce SARS-CoV-2 transmission. These are especially important for immunocompromised people, including cancer patients on active treatment, people with advanced or untreated HIV and organ transplant recipients.

  • Wear a well-fitted mask or respirator indoors and in crowded outdoor settings.
  • Wash your hands with soap and water frequently.
  • Use hand sanitizer containing at least 60% alcohol.
  • Stay home if you are sick.

Changes in prevention guidelines over time reflect an evolving understanding of how the virus spreads. Early guidelines emphasized cleaning surfaces, but it later became apparent that this is not a common transmission route. Similarly, it became clear that most outdoor activities pose a low risk.

Health officials initially advised against wearing masks, then recommended any sort of face covering. This advice changed when it became clear that well-fitted respirators, such as an N95 or KN95, offer the best protection. Make sure your mask fits snugly and completely covers your nose and mouth. A good mask can protect you even if others don’t wear them.

More stringent measures—such as stay-at-home orders and closure of schools and businesses—were implemented before vaccines were available and hospitals were at risk of being overwhelmed. These measures have been lifted now that most of the population has some immunity due to prior infection or vaccination.

There are also some measures you can take to lower the risk of developing severe COVID-19 if you do catch the virus. These include quitting smoking, maintaining a healthy weight, getting treatment to manage preexisting health conditions and taking the antiviral drug Paxlovid. While COVID vaccines do not reliably prevent infection or mild illness, they offer the best protection against severe disease.

Last Reviewed: September 15, 2021