Six health care workers in the US who were in close contact with a patient known to have bird flu developed mild respiratory symptoms, according to the US Centers for Disease Control and Prevention (CDC).

The patient was not known to have had contact with livestock or other animals, raising the possibility of human-to-human spread. Only one healthcare worker was tested for the H5N1 bird flu virus, but the results were negative.

Infections caused by the latest variant have symptoms including fever, chills, fatigue, cough, congestion and headache.

The public, by and large, has not been on board with immunizations in the aftermath of the pandemic, despite public health agencies heavily campaigning this year for more people to get vaccinated against COVID-19,