If you test positive for COVID-19, you may wonder how long you remain contagious and should isolate from others. Here is a quick overview of how long you are likely to be contagious after testing positive for COVID-19:
- Day 0-2: You are very likely to be contagious around the time of testing positive.
- Day 3-5: You remain very contagious, with peak viral load.
- Day 6-10: You are likely still contagious, but viral load starts decreasing.
- Day 11-14+: You are potentially contagious but pose a lower transmission risk.
However, the duration of contagiousness varies from person to person. In general, you should isolate for at least 5 days after symptoms start and 24 hours after fever ends. Severely immunocompromised people and those in high-risk settings may need to isolate for 10+ days.
What Does It Mean to Be Contagious?
When we talk about being contagious with COVID-19, it means you can potentially transmit the SARS-CoV-2 virus to other people. The virus spreads through respiratory droplets and aerosols released when you cough, sneeze, talk, sing, or breathe.
You are considered most contagious when your viral load is at its highest. Viral load refers to the amount of detectable virus in your system. When your viral load is high, your infected respiratory secretions contain more virus that can be expelled and infect others.
Timeline of Contagiousness After Testing Positive
Here is a more detailed timeline of how long you are likely to be contagious after testing positive for COVID-19:
0-2 Days After Testing Positive
You are very likely to be contagious around the time you test positive or just prior. The PCR test can detect SARS-CoV-2 when your viral load is still ramping up but high enough to trigger a positive result.
This means you may have gotten infected 1-3 days before testing positive. You may be asymptomatic or pre-symptomatic and feeling fine, yet quite contagious.
3-5 Days After Testing Positive
You are typically very contagious during this period. Viral load reaches its peak around 3-5 days after infection on average. More virus in your system means you are more likely to spread it to others.
You may start experiencing COVID-19 symptoms like fever, cough, fatigue, sore throat, etc. There is debate around whether pre-symptomatic transmission (before feeling sick) or symptomatic transmission is more contagious.
6-10 Days After Testing Positive
You remain likely to be contagious during this time, but generally pose a decreasing transmission risk as your viral load declines. Most people recover around 10-14 days after symptoms start.
You may still have symptoms, but they should be improving. Severely ill people can have high viral loads for longer periods.
11-14 Days After Testing Positive
At this point, you are less likely to be contagious, but it still varies from person to person. Your viral load continues to decline, making you less infectious, although you could remain PCR positive.
Most people feel recovered by now. However, you may need to isolate for longer if you are still symptomatic or severely immunocompromised.
15+ Days After Testing Positive
After two weeks, you pose a significantly lower – but not zero – transmission risk to others. Viral load and contagiousness decrease over time, but some people may remain contagious for over two weeks.
At this point, you should no longer have COVID-19 symptoms. But approximately 20% of people remain PCR positive after two weeks. Discuss leaving isolation with your doctor if needed.
Key Factors That Affect Contagious Period
Several key factors impact how long you are contagious after testing positive for COVID-19:
Vaccination Status
In general, fully vaccinated people tend to have lower viral loads, shorter symptomatic periods, and become less contagious faster than unvaccinated people. One study found vaccinated people were contagious for 6 days vs. 9 days for unvaccinated.
COVID Variant
More transmissible variants like Delta and Omicron can lead to higher initial viral loads and longer contagious periods. For example, Delta may cause contagiousness for 8+ days vs. 5 days for earlier strains.
Age and Health Status
Older age, underlying conditions, and weakened immune systems are linked to higher viral loads over longer periods. This makes people more contagious for longer – often 10+ days.
Severity of Illness
People with moderate to severe COVID-19 who are hospitalized tend to have very high viral loads for up to three weeks. Mild illnesses often peak earlier and decline faster.
Rebound Infection
Some people treated with Paxlovid experience COVID-19 rebound 5-8 days later as medication wanes. This can lead to repeat contagiousness, requiring additional isolation.
How Long Should You Isolate After Testing Positive?
The CDC currently recommends you isolate from others for at least 5 days after your symptoms start, and 24 hours after your fever resolves without medication.
However, they note you are likely most contagious during the 1-2 days before symptoms start, and 2-3 days after. So you may need to isolate for 6-10 days total.
You should wear a well-fitted mask if you must be around others at home and in public during days 6-10. Avoid travel and high-risk settings like nursing homes until after day 10.
However, severely immunocompromised people and those in high-risk settings may require longer isolation of 10-20 days. Speak to your doctor about an appropriate contagiousness timeline.
Vaccinated People
Fully vaccinated people appear to shed virus for a shorter period of time compared to unvaccinated people. But current isolation guidance is the same regardless of vaccination status.
Asymptomatic People
Those who never develop COVID-19 symptoms should isolate for at least 5 days from their positive test date. Wear a mask and avoid high-risk settings through day 10.
People Requiring Hospitalization
Severely ill patients admitted to the hospital are often extremely contagious for prolonged periods. Isolation for at least 10 days and up to 20 days may be warranted based on testing.
How to Calculate Your Isolation Period
Here are some examples of how to determine your COVID-19 isolation period based on CDC guidelines:
| Date of Symptom Onset | Date Fever Resolved | Minimum Isolation Period |
|---|---|---|
| January 1 | January 3 | January 6 (5 full days) |
| January 1 | January 4 | January 7 (5 full days + 24 hours) |
| No symptoms | N/A | 5 full days from positive test |
Be sure to wear a high-quality mask through day 10 and avoid high-risk settings. Take additional precautions or isolate longer if severely immunocompromised or still symptomatic beyond 10 days.
Can You Test Out of Isolation Early?
The CDC does not currently recommend using antigen or PCR testing to end COVID-19 isolation early, even if you test negative.
PCR tests can remain positive long after you are no longer contagious. And antigen tests may not reliably detect lower viral loads. However, repeat rapid testing may provide additional insight into decreasing contagiousness.
Discuss testing and isolation timelines with your healthcare provider, especially if you need clearance to return to work or are at high-risk. Follow your doctor’s guidance and local public health guidelines.
Prevent Spreading COVID-19 to Others
To avoid transmitting the COVID-19 virus during your contagious period:
- Isolate at home except for medical care for at least 5 days.
- Ask others to drop off food/necessities and keep distance.
- Stay in a separate room and use a separate bathroom if possible.
- Wear a high-quality mask if you must be around others at home.
- Avoid contact with high-risk people, crowded places, and travel until past day 10.
- Cover coughs and sneezes, wash hands frequently, and clean common surfaces.
Notify your close contacts that they have been exposed so they can take proper precautions. Following isolation guidance is important to avoid infecting more people.
The Bottom Line
If you test positive for COVID-19, you may be contagious 48 hours before symptoms until at least 5 days after. But some people spread virus for 10 days or longer after positive test.
Isolate for 5 full days, and wear a mask around others through day 10. Avoid travel and high-risk settings during this time. Take additional precautions if you are severely immunocompromised or still symptomatic beyond 10 days.
Vaccines, masking, isolation, and treatments help reduce transmission risk. Speak to your doctor if you have questions about appropriate isolation duration and contagiousness timelines.
