Viral Shedding and What It Means for COVID-19

What is viral shedding?

When you get sick with a virus, the virus makes more copies of itself using the machinery of your own cells. These new copies leave your body and then infect other people. “Viral shedding” is the term for this process. 

The virus that causes COVID can make copies of itself very quickly. After entering your body, it attaches to a cell inside your nose or throat. From there, it uses its specialized spike protein to get inside the cell. 

Once inside a cell, the virus turns that cell into a coronavirus factory by inserting its own RNA into the cell’s machinery. At first, all the new copies of the virus stay inside the cell. But very soon, the cell bursts and dies. And all those copies of the coronavirus are set loose. 

Each new copy of the virus can go on to infect another cell in your body. Or it might “shed” into the environment when you cough or sneeze. Once in the environment, it can infect other people.

Your immune system will begin to fight back as soon as it detects the virus. It will create antibodies, or immunoglobulins, that destroy viral particles. If you’ve been vaccinated against COVID, you’ll already have some antibodies in your bloodstream and your immune system will be able to react much faster. 

How does viral shedding spread COVID-19?

The virus that causes COVID spreads primarily through respiratory droplets. That’s because the virus is usually shed into the airways, so it ends up in saliva and nasal mucus. But small numbers of viral particles can also be found in feces, urine, tears, and other fluids that come out of the body.

Here’s how people who are sick with COVID shed the virus from their nose and mouth:

• Breathing air out: The virus leaves their nose and goes into the air, where it survives in tiny water droplets. Someone nearby can then breathe in the virus.

• Coughing or sneezing: These actions spray larger droplets of water or mucus. Because these particles are moving with more speed, the virus can fly into the eyes, nose, and mouth of another person. 

• Having direct contact with others: If someone comes in direct contact with the sick person’s eyes, nose, or mouth, copies of the virus can directly cross to them. 

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How soon after COVID infection does a person begin shedding the virus?

A person with COVID infection can begin shedding virus before they know they’re sick, possibly as soon as 2 days after being infected. That means they can start shedding the virus about 2 to 3 days before they develop symptoms. They continue to shed the virus while they have symptoms of COVID. 

It’s difficult to know how soon after exposure viral shedding begins. For that reason, the CDC recommends you begin isolation immediately after being exposed.

Most people stop shedding after 7 to 10 days from when they start having symptoms. Staying up to date isolation guidance from the CDC is a great way to keep yourself and communities safe.

What are signs of shedding the coronavirus?

In general, if you have symptoms of COVID infection, you’re likely shedding the virus. This is especially true if you have a fever or just started having symptoms in the past week. Most people are most contagious with COVID during the first 5 to 7 days after infection. 

What’s the difference between viral shedding and infectiousness? 

Viral shedding is what makes a person contagious when they have a virus. 

Infectiousness, on the other hand, is a characteristic of the virus itself. Certain strains of COVID are more infectious than others, which means they’re more likely to make you sick if you catch them. For example, the most recent strain — JN.1 — is more infectious than previous strains.

This is confusing because the words “infectious” and “contagious” are used interchangeably.

How do you stop viral shedding?

There’s no way to stop viral shedding. But there are ways to help prevent shedding from infecting other people, such as:

• Physical distancing: The farther apart people are, the harder it is for the virus to spread to another person. 

• Masks: Masks work as a physical barrier to trap the virus particles so they can’t spread to another person. Masks work best if they fit tightly and have multiple layers. 

• Vaccines: People who are vaccinated against COVID are less likely to get sick and shed the virus, and this lessens the spread of the virus. 

• Isolation: People who are sick with COVID should isolate. This keeps them away from others while they are shedding. 

Why trust our experts?

Written by:

Shiv Sudhakar, MD

Shiv Sudhakar, MD, is a fellow of the Infectious Disease Society of America and works as a physician in California. He has co-authored over 10 peer-reviewed research articles and given 20 scientific presentations.

Edited by:

Alex Eastman, PhD, RN

Alex Eastman, PhD, RN, is a California-based registered nurse and staff medical editor at GoodRx, where he focuses on clinical updates and Latino health.

Reviewed by:

Kerry R. McGee, MD, FAAP

Kerry McGee, MD, FAAP, has over a decade of experience caring for babies, children, and teenagers as a primary care pediatrician. She has a special interest in adolescent health, particularly in adolescent mental health.

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