When a baby tests positive for COVID-19, caregivers are primarily concerned with how long they remain contagious. Unlike adults, infants and young children often present with milder or atypical symptoms, complicating the assessment of their infectious period. Current guidelines for contagiousness are now broadly aligned with recommendations for other respiratory viruses. The end of contagiousness is determined by the resolution of the infant’s symptoms, not a fixed number of days.
Defining the Standard Isolation Period
The current recommendation for ending isolation is based on symptom improvement, moving away from a fixed five-day period. An infant or child who tests positive should stay home until their symptoms are getting better overall. They must also be fever-free for at least 24 hours without the use of fever-reducing medication. This guidance aligns the COVID-19 isolation period with that of other common respiratory illnesses, such as the flu.
The contagious period generally peaks early in the illness, often one to two days before symptoms begin and within the first few days of symptom onset. Although the majority of virus transmission occurs during this early window, infants can still shed the virus for up to eight to ten days after symptoms first appear. Returning to normal activities should only happen once both the fever and symptoms have significantly improved for a full day.
When Contagiousness May Last Longer
While the symptom-based approach covers most uncomplicated cases, certain factors can significantly extend the time a baby remains contagious. Infants younger than one year old are considered at a higher risk for severe illness. Those with moderate or severe illness, especially if they required hospitalization or have persistent symptoms, may need a longer period of isolation.
The isolation period is substantially longer for infants who are moderately or severely immunocompromised due to underlying health conditions or medical treatments. Because their immune system takes longer to clear the virus, they can shed viable virus particles for an extended duration. Isolation has previously been recommended for up to 20 days after symptoms began for these patients. In severe cases, a severely immunocompromised child may shed the virus for months, requiring a doctor’s guidance and specific testing to determine when isolation can safely end.
Testing and Safety After Isolation
Once an infant meets the criteria to end isolation—symptoms are improving and they are fever-free for 24 hours—extra precautions are still advised for a specific period afterward. For five days following the end of isolation, caregivers should implement added safety measures to minimize the risk of any continued transmission.
These precautions include enhanced hygiene practices, taking steps for cleaner air, and wearing a well-fitting mask when the infant is around others, particularly in indoor settings. While at-home rapid antigen tests are not authorized by the FDA for children under two, they can be safely administered by caregivers and are useful for identifying infection. A negative rapid antigen test offers reassurance, as a positive result reliably indicates infectious viral presence.
A positive result on a highly sensitive PCR test may persist long after the infant is no longer contagious, however. This is because the PCR test detects residual genetic material, not necessarily live virus. The most practical safety measure post-isolation involves avoiding contact with high-risk individuals, such as the elderly or those who are immunocompromised, for the full five-day precaution period.