How does COVID-19 spread?

How COVID-19 spreads

COVID-19 primarily spreads through the air. When an infected person breathes, talks, coughs, or sneezes, they release tiny droplets and particles, called aerosols, into the air. These particles can float in the air and be inhaled by others, especially in indoor spaces with poor ventilation where the air doesn’t move as much.

Being close to someone who has COVID-19 (within about 6 feet) increases your chances of being infected because you might breathe in the droplets they release into the air.

Surface transmission of COVID-19 is possible, but less common. While the virus can survive on surfaces for hours or even days, getting sick this way is rare. It can potentially happen if you touch a contaminated surface and then touch your mouth, nose, or eyes, but surface transmission is not the main way COVID-19 spreads.

When is someone with COVID-19 contagious?

People infected with COVID-19 can be contagious up to 2 days before symptoms appear and can remain so for about 10 days after. This means someone can spread the virus without even knowing they’re sick. To learn more, visit how long people with COVID-19 can spread the virus.

If you have been exposed to COVID-19 or feel unwell, remember to stay home and away from others and test for illness.

Because older adults and people with certain medical conditions are at higher risk, 3 out of 4 adults (75%) in the U.S. are at high risk of severe illness. Taking the COVID-19 Risk Assessment can help you better understand your likelihood of severe illness. For those more likely to experience severe illness, prescription medications are available to treat COVID-19.

What conditions help a virus spread?

Certain environments can make it easier for viruses to move from person to person. COVID-19 tends to spread more easily when:

• Air is cool and dry: This is more common in winter months, although COVID-19 can spread at any time
• Ventilation is poor: Crowded indoor spaces with little fresh air can increase the chance for transmission.
• Population density is high: More people in one place means more chances for the virus to move from person to person.
• Hygiene is lacking: Not washing hands or cleaning surfaces can help the virus spread.

How to prevent the spread of viruses

Even though viruses, like COVID-19, can be highly contagious, there are ways to help limit their transmission:

• Improve ventilation in indoor spaces by using air purifiers or opening windows.
• Wash hands regularly and clean high-touch surfaces when you or someone you live with is sick.
• Stay home and away from others if you test positive or feel sick.

If you are experiencing symptoms or test positive, talk to a healthcare provider. COVID-19 can become more severe, especially for people 50+ or with certain underlying medical conditions.

Know how COVID-19 spreads and take action to avoid it

From airborne particles to crowded indoor spaces, knowing the ways COVID-19 can spread allows you to stay informed, take precautions, and be prepared if you are at high risk for severe illness.

Consider taking the COVID-19 Risk Assessment to understand your risk. If you’re at higher risk of developing severe illness, prescription medications exist, but they must be taken within the first 5 days of symptoms.