Surging cases of bird flu among mammals, including U.S. cattle, offer a stark warning that the world is not ready to fend off future pandemics, a report said, urging leaders to act quickly.

More than four years since the start of the COVID-19 pandemic, politicians are "gambling through neglect" by not putting enough money or effort into avoiding a repeat of the disaster, the report said.

The bird flu H5N1 has been increasingly spreading to mammals, including cattle in farms across the U.S. and a few humans, prompting fears the virus could spark a future pandemic.

"If H5N1 began to spread from person to person, the world would likely again be overwhelmed," the report's co-author and former New Zealand Prime Minister Helen Clark told a news conference.

It could even be "more disastrous, potentially, than COVID-19," Clark said.

"We just aren't equipped enough to stop outbreaks before they spread further," she said, pointing to a deadlier strain of monkeypox particularly affecting children in the Democratic Republic of Congo.

While wealthy countries have vaccines that could fight this monkeypox outbreak, they have not been made available to the central African country, she pointed out.

Now, two people have died from the strain in South Africa, illustrating how neglect can lead to such pathogens spreading, she stressed.

The report was led by Clark and Liberian ex-President Ellen Johnson Sirleaf, who previously served as co-chairs of an independent panel advising the World Health Organization (WHO) on pandemic preparedness.

Despite the advice from the panel in 2021, "the funds now available pale in comparison to the needs and high-income countries are holding on too tightly to traditional charity-based approaches to equity," Clark said.

The report pointed out that WHO members have still not sealed a much-discussed pandemic agreement, mainly due to differences between well-off nations and those who felt cut adrift during the COVID-19 crisis.

The report called for governments and international organizations to agree to a new pandemic accord by December, as well as funding more efforts to boost vaccine production, bolstering WHO's power and boosting national efforts to fight off viruses.

To emphasize the potential threat, the report pointed to modeling research suggesting there is a one-in-two chance the world will suffer a pandemic of a similar size to COVID-19 in the next 25 years.