How Long Are You Contagious With COVID-19? – Verywell Health

If you test positive for COVID-19, the duration of contagiousness can vary. This is because the virus can be shed (meaning released from the body through talking, exhaling, etc.) for anywhere from days to months depending on your age, vaccination status, immune status, severity of infection, and any preexisting conditions you may have.

Even so, the likelihood of transmission decreases as fewer viruses are shed over time. Based on current evidence, the Centers for Disease Control and Prevention (CDC) recommends isolating for at least five days if you have mild or asymptomatic COVID-19 and at least 10 days if you have moderate to severe COVID-19.

Other interventions, such as face masks and the avoidance of close contact, can help prevent the spread of the SARS-CoV-2 virus that causes COVID-19 once you leave isolation.

This article explains how long COVID-19 is contagious and the variables that can increase or decrease the duration. It also offers tips on how to protect others if you or someone know gets COVID-19.

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As a general rule, most people who get COVID-19 are no longer contagious 10 days after the appearance of symptoms or after testing positive for the virus. While there is significant variation in the risk of transmission, most cases follow the same general timeline once symptoms develop.

When you are infected with COVID-19, the virus goes through what is called the incubation period. This is the time between exposure to the virus and the first appearance of symptoms. With COVID-19, the incubation period is generally two to three days following exposure.

During this period, viral particles will start to be shed through exhaling, talking, laughing, and other means. So, even if there are no symptoms, the infected person can still unwittingly transmit the virus to others. This is why the disease is so hard to control.

When symptoms do developand the number of viruses in the body (called the viral load) continues to increasea person will be at their peak contagiousness and most able to transmit it to others.

The current body of evidence suggests that the peak contagiousness of COVID-19 is around three days after the first appearance of symptoms. This is when the viral load in most people with COVID-19 is at its highest and right before the immune system reins the infection in.

However, this shouldn't suggest that everyone with COVID-19 peaks at the same time or even that a drop in your viral load corresponds to a drop in viral shedding.

A 2023 study from Northwestern University found that people with COVID-19 exhale as many as 800 copies of the virus per minute during the first eight days after symptoms appear. So, even though the viral load may be dropping, infectious viral particles may continue to be exhaled.

This further reinforces the need for face masks and other preventive measures once isolation typically ends (after the fifth day following symptom onset or a positive test).

There are situations in which the contagiousness of COVID-19 extends well beyond 10 days. According to the CDC, people with severe COVID-19 or those who are moderately to severely immunocompromised may remain contagious for longer and need to isolate for 20 days or even more.

Studies have repeatedly shown that the duration of viral shedding increases with the severity of the infection (such as when pneumonia or severe respiratory distress is involved). In such cases, the viral load can remain persistently high, increasing the duration of contagiousness to well over a month in rare instances.

If you are immunocompromised, the duration of contagiousness can be longer simply because it takes longer for the immune system to control the infection. While there is no rule as to how much longer that might be, a 2023 study in the journal Pathophysiology reported that immunocompromised people have a median viable viral shedding period of four weeks.

This includes people on chemotherapy, organ transplant recipients on immunosuppressants, and people with advanced untreated human immunodeficiency virus (HIV).

Some COVID variants are more virulent (able to be passed) and pathogenic (able to cause illness) than previous strains. This is because, as the virus mutates, the mutations that are best able to survive are those that can escape immune detection.

When this happens, the immune cells that were once able to stop COVID-19 at the frontlines are less able to do so, increasing the risk of transmission.

An example of this is the Omicron variant first identified in 2021. Before Omicron, the peak contagiousness of the virus was two days before symptoms appeared and three days afterward, with viral shedding peaking on or before the appearance of symptoms.

With the emergence of Omicron, the peak of viral shedding was two to three days later.

It is possibleand perhaps likelythat future variants will become more virulent even if they aren't necessarily more pathogenic.

This is evidenced by the Delta variant, the 12th variant first seen in 2020. According to a study published in the Frontiers of Public Health, the duration of infectious shedding of the Delta variant was more than twice as long as the SARS-CoV-2 virus back in 2019.

It is estimated that more than 1 of every 3 COVID-19 infections in the United States are asymptomatic. This presents a significant public health challenge as viral sheddingand the spread of the viruscan still occur even in the absence of symptoms.

According to research from the CDC, no less than 24% of all COVID-19 infections in the United States are the result of asymptomatic transmission.

Even so, asymptomatic infections tend to be less virulent than symptomatic infections, partly because the peak viral load tends to be lower. In some cases, the duration of contagiousness may be no longer than three days.

Concerning infectious shedding, the average duration is nine days for someone symptomatic for COVID-19 vs. only six days for someone asymptomatic for COVID-19.

This supports the current CDC guidance recommending isolation for five days if you test positive for COVID-19, even if you have no symptoms.

Generally, COVID-19 infections in children and adolescents cause less severe illness and fewer deaths than in adults. Research suggests that children may also be less susceptible to COVID-19 infection.

According to a 2021 review of studies involving 41,640 children and 268,945 adults, the risk of COVID-19 transmission was 56% less to kids than to adults. Even within the same household, children are nearly 60% less likely than adults to get COVID-19 from another family member.

Among the possible explanations for this, children seem to harbor fewer receptors for COVID-19called angiotensin converting enzyme-2, or ACE-2, receptorsin their upper respiratory tracts. These receptors are proteins on cells to which viral particles attach and infect the cell. As children grow into adulthood, the number of receptors increases, providing the virus more targets for infection.

This doesn't mean that a child with COVID-19 is any less able to pass the virus than adults.

According to a study in the Journal of Allergy and Clinical Immunology, which monitored 1,394 families from 2020 to 2021, children were actually more likely to transmit COVID-19 than other members of their households.

This was explained by the fact that 75% of the children were asymptomatic for COVID-19 and may have unknowingly spread the virus through nasal secretions and hand-to-nose behaviors.

COVID-19 vaccination not only decreases your risk of infection and severe illness, but it may also significantly reduce your contagiousness.

A 2022 study published in JAMA Network Open was one of several that showed that fully vaccinated people have a shorter duration of infectious viral sheddingas well as a lower risk of transmitting it to othersthan either partially vaccinated or unvaccinated people.

The study, which involved high-risk healthcare workers, hospital patients, and caregivers, found that the duration of contagiousness was roughly 10 days for unvaccinated people and eight days for partially vaccinated peoplebut only four days for fully vaccinated people.

The current CDC guidance for COVID-19 isolation varies by the severity of infection, with special consideration given to those who are moderately or severely immunocompromised.

People with mild or asymptomatic illness should isolate through at least day 5, as follows:

If you are asymptomatic with COVID-19 but then develop symptoms, you would need to restart isolation at day 0. If you have mild COVID-19 but experience a recurrence or worsening symptoms, you would also need to restart at day 0.

People with moderate to severe COVID should isolate through at least day 10, as follows:

People with severe COVID-19 (such as those who have been hospitalized or placed on a ventilator) may need to extend their isolation to 20 days as they are often infectious well beyond 10 days.

People with COVID who are moderately or severely immunocompromised should isolate through at least Day 20, as follows:

You will also need to have two consecutive negative test results 24 hours apart to confidently end isolation. If not (or if your symptoms persist), you may need to isolate well beyond 20 days. Their healthcare provider can give them guidance on what is recommended.

Health experts generally agree that COVID-19 is here to stay and that continued vigilance is needed as new variants and outbreaks emerge.

To protect yourself and others from this highly contagious virus, the CDC recommends the following preventive measures:

The contagiousness of COVID-19 can vary, but people with mild or asymptomatic illness are usually no longer contagious after 10 days. People with moderate to severe illness or who are moderately to severely immunocompromised may remain contagious for 10 to 20 days or even longer.

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How Long Are You Contagious With COVID-19? - Verywell Health