The woman, from Anhui province in eastern China, had recently visited a live poultry market.
The CDC said the latest patients have mild illness and have been offered antiviral treatment.
The state has now reported 49 outbreaks in dairy cows, nearly half of its licensed dairy farms.
Early results from blood sampling found no evidence of earlier undetected infection in Michigan dairy farm workers exposed to sick cows.
Colorado's latest layer farm outbreak occurred not far from where culling workers were infected in a similar event.
Scientists said until the newer more closely matched vaccine is approved, earlier licensed vaccines might be a useful bridge, if needed.
Investigators are exploring if conditions in sweltering barns made PPE less effective and how the genotype infecting cows turned up on the poultry farm.
The avian flu in an elephant seal from Antarctica signals further expansion of the virus in the region's vulnerable wildlife.
In other developments, a challenge study in dairy cows finds that the virus can spread by both mammary and respiratory routes.
Colorado health officials are closely monitoring and testing workers, and the CDC has a field team on the ground to assist with the response.
