The federal government is closely monitoring the rising risk of human-to-human transmission, which has yet to be seen. 

On Wednesday, the Michigan Department of Health and Human Services reported a farmworker who had high exposure to infected livestock developed mild symptoms and has recovered. 

"The current health risk to the general public remains low," Dr. Natasha Bagdasarian, Michigan's chief medical executive, said in a news release. "

Bagdasarian continued, "We have not seen signs of sustained human-to-human transmission at this point. This is exactly how public health is meant to work, in early detection and monitoring of new and emerging illnesses."

The second case was reported in Australia's southeastern state of Victoria. This is the first human case of bird flu in the country. 

For several years, the H5N1 strain of avian flu has swept the world, killing hundreds of millions of farmed and wild birds, if not more. An evolution of the virus appears to be infecting humans. 

Goldman analysts pointed out yesterday evening that "green shoots across Vax Names following reports of human bird-flu infections confirmed in the US and Australia." They noted vaccine companies, including Moderna, jumped 14%, BioNTech +11%, CureVac +18%, and Novavax +5.3%.