The researchers say healthcare providers, public health officials must encourage vaccination, especially for those at highest risk.
Levels for three viruses are elevated or rising, as the CDC warned of further impacts and urged stepped-up vaccination.
With vaccine uptake low, the CDC warns of an urgent need to increase vaccine coverage for flu, COVID-19, and RSV.
This age-group is at higher risk for severe RSV and death because of age-related immune-system weakening and a higher rate of underlying medical conditions.
The additional doses are on top of 77,000 made available in November.
As COVID markers show growing momentum, the nation's flu season continues to gain steam.
Visits for viral and respiratory illness at the 25 emergency departments included in the study rose 72% over the 4 preceding months.
Pediatric hospital bed occupancy is approaching levels seen last year due to multiple respiratory illnesses.
Federal officials have been working with companies to find ways to boost the supply of the new vaccine for newborns.
Chinese officials told the WHO that the increase in respiratory illness in children is linked to increased circulation of Mycoplasma pneumoniae and an uptick in flu, RSV, and adenovirus.