How Long Are You Contagious With COVID-19? Timeline of Exposure and Infection
Key takeaways:
People are most contagious with COVID-19 in the first 5 to 7 days after they catch the virus.
Many people don’t get symptoms right away when they catch COVID, and some never experience symptoms at all. But, in both cases, people are still contagious.
On average, people are contagious with COVID for 5 to 10 days. But some people stay contagious for longer.
Being sick with COVID-19 isn’t easy. On top of being sick, you may still need to isolate even if you only have mild COVID symptoms. While you’re contagious with COVID, staying home protects everyone in your community.
People are most contagious for the first 5 to 7 days after they get sick with the COVID virus. But most people don’t develop symptoms from a COVID illness right away. It takes a day or two after getting sick with the virus to start feeling sick. That means people are contagious and spreading the virus 1 to 2 days before they even realize they’re sick.
But when can you finally go back to your usual routines? And how can you decide when to start and end your isolation? Here’s everything you need to know about when you’re most contagious with COVID and how to figure out the COVID contagious period.
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How long is someone with COVID infectious?
The short answer is that you’re contagious with COVID for 8 to 10 days after you start showing signs of COVID illness or test positive for the COVID virus.
The full answer is more complicated. The 10-day mark seems to apply to people who have mild-to-moderate COVID illness. But people with severe cases of COVID illness can remain infectious for several weeks or months. There’s also evidence that people with a weakened immune system remain contagious for longer periods of time too.
On the other hand, some people stop being contagious before that 8-to-10 day mark. This seems to be the case for people who're fully vaccinated against COVID but get a COVID infection anyway (this is called a “breakthrough infection”). Studies show that vaccinated people who have breakthrough infections are contagious for a shorter period of time compared to unvaccinated people who get sick with COVID.
Stop the spread: Even if you’re testing negative for COVID-19, it’s best to proceed with caution. Here’s how to keep yourself and your loved ones safe if you start experiencing COVID symptoms.
Feel better fast: There’s no magic cure for a COVID infection. But if you want to reduce your symptoms quickly, certain over-the-counter (OTC) medications and at-home treatments may help.
How long does the virus live? Can the virus that causes COVID live on food, clothing, dishes, or other surfaces? Learn more about the true risk of viral contamination in your home.
Experts don’t know exactly how long a vaccinated individual can spread the virus when they get sick with COVID. This is why isolation and “stay home” recommendations are the same for everyone, regardless of whether or not they received a COVID vaccine.
How contagious is COVID?
The COVID virus is very contagious, especially now that the omicron variant has settled in as the dominant strain in the U.S.
To determine how contagious a virus is, we can look at something called a basic reproduction number. This is a measure of a virus’s ability to spread and infect other people. It’s noted as R0 and pronounced as “R-naught.”
A virus with a high R0 is more contagious than a virus with a lower R0. COVID’s R0 is estimated to be about 3. That makes COVID much more contagious than seasonal flu. It’s also more contagious than Ebola and Zika, but not as contagious as measles.
R0 offers an estimate of COVID’s ability to pass from person to person. But it’s not the full story. As more people get vaccinated and develop immunity to COVID, the virus’s ability to spread goes down. But in response, the COVID virus mutates so it can overcome these barriers and spread more easily.
It may take a few more years before scientists can fully answer this question. But for now, it’s clear that COVID is very contagious and spreads easily from person to person.
When do you become contagious after exposure to COVID?
You might start being contagious with COVID-19 on the same day you’re exposed to the virus. Viral shedding can occur as soon as you pick up the virus. That’s why it’s possible to spread COVID even before your symptoms start.
Research shows that people typically have the highest levels of the virus in their body, also called peak viral load, about 3 to 5 days after their COVID symptoms start. People are most contagious during the days when their viral loads are very high.
What is viral shedding?
Viral shedding happens when a sick person releases copies of a virus from their body. Large numbers of viruses are shed when a sick person coughs or sneezes. But viruses can also be shed when you talk, cry, or breathe. Viral shedding is how viruses spread from person to person.
People typically shed the virus that causes COVID for about 10 days, starting 2 to 3 days before they develop symptoms. People are contagious with COVID while they shed the virus.
You can assume you’re shedding the COVID virus if:
You have a fever.
You have COVID symptoms that haven’t gotten better yet.
But you can’t rely on symptoms alone to tell you if you’re shedding the virus. Some people who get sick with COVID never develop symptoms. But these people can still shed the virus, so they’re still contagious.
That’s why experts recommend taking a COVID test if you’ve been exposed to someone with COVID illness, even if you have no symptoms.
When do you stop being contagious if you have COVID?
It depends. If you have a mild illness and your symptoms are getting better, you’re probably no longer contagious after 10 days.
On the other hand, if you have a severe illness or a weakened immune system, you can be contagious for much longer.
But if you’ve been fully vaccinated against COVID, you may be contagious for a shorter period of time. It’s hard to know exactly.
Isolation guidelines for preventing the spread of COVID
In the past, all this uncertainty made it hard to know when you could stop isolating if you were sick with COVID. But thankfully, the CDC has simplified the approach to isolation for people who're sick with COVID.
The CDC now recommends that people who’re sick with COVID isolate until both of the following are true:
They’re fever-free without the help of medication for 24 hours.
Their symptoms are getting better.
This applies to people who’re up-to-date with COVID vaccines and those who aren’t.
Once you’ve hit these milestones, you can go back to work, school, and your normal routine. But the CDC recommends that you take additional precautions for the next 5 days so you don’t spread the virus to others. These include:
Frequent hand washing
Covering your cough and sneezes
Using HEPA filters and increasing ventilation in indoor spaces
Testing if you’re going to be around people at risk for severe COVID illness
Restart this process if at any point your symptoms get worse again or your fever comes back.
If you’re vaccinated, are you still contagious if you get COVID?
People who're fully vaccinated against COVID can still get sick. But they’re less contagious if they do get sick. They’re also much less likely to develop serious COVID illness.
Getting vaccinated against COVID not only protects you: It protects everyone around you. It helps stop the spread of COVID, and it’s the best way to protect yourself and your loved ones.
Frequently asked questions
Mild-to-moderate COVID illness can last anywhere from 1 to 14 days. People who're up-to-date with their COVID vaccines are more likely to develop mild illness and recover quickly. Their COVID infection may only last 1 day.
People who're not up-to-date with their vaccines are more likely to develop a longer illness. People with certain medical conditions or those with weakened immune systems may develop longer illnesses too.
It’s possible to test positive for COVID and not be contagious. But this happens in situations where people have already recovered from their COVID illness but continue to have positive tests. It’s very likely that you’re contagious if you test positive for COVID and have a fever or feel sick.
The bottom line
Most people with COVID-19 illness are contagious for about 10 days. People with severe illness or a weakened immune system can be contagious for longer. People who're fully vaccinated are contagious for shorter periods of time. If you’re contagious, you can pass the virus to other people.
Make sure to isolate until your symptoms are getting better and you’re fever free for 24 hours without the help of medication. Wear a mask, follow physical distancing guidelines, and wash your hands frequently for 5 days after you end your isolation. Restart the isolation process if your symptoms get worse or your fever comes back.
Why trust our experts?
References
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