https://www.mercurynews.com/2022/01/06/yes-you-can-have-covid-19-but-test-negative/

Rapid antigen tests may miss detection of COVID-19’s omicron variant during the first early days of infection, according to a new small study.

The findings, if confirmed, urge against over-reliance on a tool that has become the cornerstone of reopening in-person businesses, schools and social gatherings.  While important, testing should be just one part of a broader preventive strategy of masking, good ventilation and small gatherings, said experts.