Most people test positive for RSV for about 8 to 14 days after symptoms begin, though the exact window depends on your age, the type of test used, and how well your immune system fights the virus. Infants and immunocompromised individuals can test positive for significantly longer, sometimes weeks after symptoms have cleared.
Average Duration by Age
A large community study tracking RSV infections found that the average duration of viral shedding (the period when the virus is detectable in your body) is roughly 11 days. But that average masks a wide range depending on age. Infants shed the virus for about 18 days on average, while adults 15 and older shed it for closer to 9 days. Children between those age groups fall somewhere in between.
Younger children, especially those under 1 year old, carry higher viral loads and clear the virus more slowly. Research on outpatient children confirmed that the estimated time to viral elimination decreases as age increases. This means a 3-month-old with RSV is likely to test positive for days longer than a 5-year-old with the same infection, and considerably longer than an adult.
PCR Tests Stay Positive Longer Than Rapid Tests
The type of test matters a lot. Molecular tests like PCR are extremely sensitive and detect tiny fragments of viral genetic material. These tests can remain positive for weeks after an infection, even when no live, infectious virus is left in your body. The leftover genetic material is essentially debris from a cleared infection, not evidence that you’re still sick or contagious.
Rapid antigen tests, by contrast, are best at picking up RSV in the first few days of illness when viral levels are highest. Their sensitivity starts relatively low and climbs to around 90% by the fourth day of symptoms. As your viral load drops, rapid tests are more likely to turn negative while a PCR test would still read positive. So if you’re retesting to see whether you’ve cleared the virus, a rapid antigen test gives you a more practical answer about whether significant amounts of virus remain.
False positives on rapid RSV tests are uncommon, occurring in roughly 1 to 2% of cases. Some of those may actually reflect recent infections with residual low-level virus rather than true errors.
Who Tests Positive the Longest
Three groups tend to test positive well beyond the typical 11-day window:
- Infants under 1 year: Their immature immune systems clear the virus slowly. An average of 18 days of shedding is normal, and some babies shed virus even longer.
- Immunocompromised individuals: People with weakened immune systems from transplants, chemotherapy, or immune disorders can shed RSV for many weeks. This prolonged shedding has implications not just for testing but for spreading the virus to others.
- People with severe lower respiratory infections: Hospital-based studies have found that patients with severe RSV pneumonia shed virus for approximately 7 days or more, and the combination of severity plus young age or immune compromise can extend that timeline further.
Babies and immunocompromised people may remain contagious for up to four weeks after symptoms resolve, according to Cleveland Clinic. That’s a much longer contagious window than the typical adult experiences.
Testing Positive vs. Being Contagious
A positive test does not always mean you’re still infectious. This distinction is especially important with PCR testing. Viral panels detect nucleic acid from the virus, but the presence of genetic material doesn’t guarantee live virus is present. One study found that roughly half of all viral detections in people tested weekly over a year were completely asymptomatic, meaning the test picked up traces of virus in people who felt fine and likely posed minimal risk to others.
That said, the line isn’t perfectly clean. Some research has found that samples taken more than 10 days after symptom onset, even those with relatively low viral levels, occasionally still yielded live, culturable virus. So while the chance of being contagious drops significantly after the first week or so, it doesn’t hit zero on a predictable schedule for everyone.
When You Can Return to Normal Activities
The CDC groups RSV with other respiratory viruses in its return-to-activity guidance. You can go back to your normal routine when both of these have been true for at least 24 hours: your symptoms are improving overall, and you haven’t had a fever without using fever-reducing medication.
After that, the CDC recommends taking extra precautions for the next five days. That includes wearing a well-fitted mask around others indoors, improving ventilation, practicing good hand hygiene, and keeping distance from people who are at high risk for severe illness. If you tested positive but never developed symptoms, the same five-day precaution period applies from the date of your positive test.
If your fever returns or your symptoms worsen after you’ve resumed activities, go back to staying home until you meet the 24-hour improvement threshold again, then restart the five-day precaution window.
Practical Takeaways for Retesting
There’s no official recommendation to retest before returning to normal life. Unlike with some other infections, a negative RSV test is not required for going back to work or school. If you do retest, keep the test type in mind. A rapid antigen test turning negative is a reasonable sign that your viral load has dropped substantially. A PCR test staying positive two or three weeks out doesn’t necessarily mean you’re still a risk to others.
For parents of young children in daycare, the practical reality is that most kids remain contagious for one to two weeks after symptoms start. Infants, especially those under 6 months, may shed virus longer and should be kept away from other vulnerable babies for a more extended period when possible.