The WHO routinely has spent about $200 million a year on travel expenses, more than what it doles out to fight some of the biggest problems in public health, including AIDS, tuberculosis and malaria combined.

The UN health agency says "plain packaging" on tobacco products has shown to be an effective complement to health warnings, advertising restrictions, and curbs on misleading packaging to help save lives.

The WHO is debating how to reform itself after botching the response to the Ebola outbreak, a sluggish performance that experts say cost thousands of lives.