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My toddler tested positive for RSV at the beginning of the week. We are supposed to travel this weekend to see family. How long is my son contagious? We’re visiting grandparents and a new baby.
—Amanda
The length of contagiousness for viruses is always a little hard to measure — for COVID, for example, we still do not really know the distribution. For RSV, our best data comes from a detailed study of a set of Kenyan households where members were tested repeatedly for RSV, regardless of whether they had had symptoms. In that study, they can measure the duration of viral shedding.
The average duration of viral shedding is around 11 to 14 days. This number is longer in young children than adults. Viral shedding is not exactly the same as being contagious, but it is a close proxy.
If you were visiting only healthy adults, I think you could make a case for this being close to the line — it’s about 11 days between the positive test and your upcoming visit, and the infectious period likely started considerably before the positive test. But with a new baby and older adults, I am afraid I would say skip it unless you get another negative RSV test before you go. I’m sorry!
(Note: An RSV vaccine is available for older individuals and during pregnancy — as well as a monoclonal antibody immunization for infants in their first RSV season. You may ask if the people you are visiting are protected!)
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