A team of researchers from the National Institute of Health performed a detailed study including extensive clinical tests and advanced brain imaging of a large group of federal employees diagnosed with anomalous health incidents (a.k.a. Havana Syndrome) and a matched control group.  Unlike prior published reports in smaller groups of subjects with Havana Syndrome, they found no evidence of inner ear or brain damage. In addition to the size and depth of the study, other key differences from prior studies were inclusion of an appropriate control group and detailed statistical analysis.  This along with the recent report of combined US intelligence agencies concluding there was no evidence for a sonic or microwave weapon should reassure symptomatic employees that they did not suffer permanent brain damage which should help with the recovery process. 

Unfortunately, as the accompanying editorial indicates, some physicians continue to speculate that a sonic or microwave weapon may have been used in attacks on at least some of the employees.  This, despite the fact that no evidence of weapons has been found despite years of search or that such weapons even exist.  Furthermore, there is extensive data regarding accidental human exposure to ultrasound and microwaves and the clinical picture is completely different from that of Havana Syndrome.