Illinois will join the World Health Organization's Global Outbreak Alert and Response Network (GOARN) following the United States' departure from the UN health agency last month, Governor JB Pritzker, a Democrat, said on Tuesday.
The move makes Illinois the second US state to join the program in defiance of US President Donald Trump, after California, also led by a Democratic governor, joined in January.
The US formally left the WHO last month after completing a one-year waiting period following an executive order that Trump signed on his first day back in office in January 2025.
"I refuse to sit by as Donald Trump undermines science and weakens our nation's ability to detect and respond to global health threats," Pritzker, an outspoken Trump critic, said in a post on social media website X.
"By joining the World Health Organization’s coordinated network, GOARN, we are ensuring that our public health leaders - and the public - have the information, expertise, and partnerships they need to protect the people of our state," Pritzker said in a statement.
The network responds to public health events worldwide, such as pandemics and disease outbreaks, and comprises more than 360 technical institutions.
California became first state to rejoin WHO after US departure
Additionally, two weeks ago, California said it would become the first US state to join the World Health Organization's global outbreak response network.
California Governor Gavin Newsom decried the United States' move, calling it a "reckless decision" that will hurt many people.
"California will not bear witness to the chaos this decision will bring," Newsom said in a statement.
"We will continue to foster partnerships across the globe and remain at the forefront of public health preparedness, including through our membership as the only state in WHO’s Global Outbreak Alert & Response Network."
The governor's office confirmed he had met with the WHO Director-General, Dr. Tedros Adhanom Ghebreyesus, at the World Economic Forum in Davos, Switzerland, that week, to discuss collaborating to detect and respond to emerging public health threats.