H5N1 is in a better position than ever to move between species and spill over aggressively into humans: This bird flu virus is now thought to have been spreading among dairy cows for many months, and federal regulators have found viral fragments circulating widely in the commercial milk supply chain across the United States (though live virus has not been found).
The one person we know of so far who has tested positive for infection (a mild case) was a Texas dairy worker. Agricultural workers have always been an underprotected population for zoonotic diseases, including influenza viruses of animal origin. When it comes to H5N1, the dairy work force — which includes on-farm workers and milkers, people working in the milk processing plants and in slaughterhouses, truck drivers and other professionals who come onto farms — is among those with the highest exposure.
Not only do we owe these at-risk workers better protection, but we also must do a much better job — immediately — of monitoring and testing them to ensure the virus doesn’t spread beyond our control. Otherwise, we might not find out about a significant outbreak in humans until it’s too late. So far, bird flu testing of this cohort has been woefully inadequate. Testing is usually under the purview of state authorities following federal Centers for Disease Control and Prevention guidelines. Tests are recommended for symptomatic workers. The exact number of dairy workers and other people who have so far been tested for H5N1 is not publicly available at the federal level. There is no excuse to continue only limited testing of this vulnerable population. Any serious surveillance efforts of H5N1 demand that the country do better to ensure proper testing and health care is provided to these workers now, lest we risk being caught flat-footed by a new pandemic so soon after Covid.