A strain of deadly bird flu that has a high risk of becoming a pandemic is surging in China, and experts are warning that the US isn’t making the necessary preparations.

According to the latest assessment from the World Health Organization, China has had 555 lab-confirmed human cases of the H7N9 bird flu virus since last October — the most of any flu season since the virus was first reported in humans in 2013.

This makes the current outbreak the largest on record for H7N9, a virus that typically circulates around poultry markets and can cause pneumonia or death when it spreads to people. Forty percent of those with confirmed H7N9 infections have died — including at least 179 people in China this year alone. That’s a very deadly pathogen.

The risk of the current outbreak causing a global epidemic is low, the WHO said. Almost all of the current infections were caught directly from infectious birds, and there’s no evidence yet of ongoing human-to-human transmission.

But whenever bird flu spreads to people, there’s always the worry that it will mutate to become more contagious.

WARNING: America isn't ready & the Trump Admin--understaffed, inexperienced, isolationist--DEFINITELY isn't ready: https://t.co/axMBv9E5Rc — Ronald Klain (@RonaldKlain) February 28, 2017

The people most at risk of H7N9 virus right now are those who visit poultry markets in China. Vietnam should also be on guard; the virus has surfaced there as well.

But if this H7N9 outbreak were to spread further, experts say the United States is not ready.

“America has long been unprepared for a dangerous pandemic, but the risks are especially high under President Trump,” the former Ebola czar Ron Klain told Vox.

Trump hasn’t yet named nominees for a new head to the Centers of Disease Control and Prevention, the agency that would lead a pandemic response. He also hasn’t nominated anyone to head Assistant Secretary for Preparedness and Response, or USAID — two other key agencies in a pandemic.

With the promise to repeal the Affordable Care Act, Trump is poised to gut a key public health fund that accounts for 12 percent of the CDC’s budget, and he’s reinstated the global gag rule, which depletes global health funding. “His proposed cuts in foreign aid,” Klain added, “will devastate work to detect and combat disease outbreaks abroad — the very best way to prevent those diseases from coming to America.”

If it’s not a bird flu outbreak, it’ll be some other health threat. The pace at which pathogens are flying around the globe and threatening pandemics is only accelerating. Over the past decade, the WHO has declared four global health emergencies. Two of them happened during President Obama’s tenure (Ebola and Zika). There’s slim chance Trump will finish a four-year term without facing an outbreak of some kind.

As for H7N9, it’s very possible it could spread to birds and people in other countries, said Dr. Tim Uyeki, a medical epidemiologist in CDC’s influenza division.

“Among the viruses we’ve assessed … H7N9 is the most concerning. It’s at the top of the list,” Uyeki said. “We don’t know when the next pandemic is going to start, where it’s going to start. But at this time the biggest concern is the H7N9 virus.”

Treating the current cases is also proving to be a challenge, since some seem to carry genetic markers associated with drug resistance to antiviral treatments for the disease, like Tamiflu. A recent assessment from the CDC also shows the virus has also split into a new lineage — which is a problem because the vaccine development for H7N9 was based on an older lineage of the virus. So we don’t have any vaccine candidates in the pipeline to fully address the current outbreak.