The head of the World Health Organization, or WHO, has called the COVID-19 vaccine crisis "scandalous" and warned that the world remains in a dangerous situation.

In his opening remarks to the 74th World Health Assembly on Monday, WHO Director-General Tedros Adhanom Ghebreyesus said that more cases have been reported so far this year than in the whole of 2020, and that if the trend continues, the number of deaths from COVID-19 will overtake last year's total within the next three weeks.

"No country should assume it is out of the woods, no matter its vaccination rate," he said.

He said that no variants have so far emerged that significantly undermine the efficacy of vaccines, diagnostics or therapeutics. "But there is no guarantee that will remain the case," he added.

Tedros lashed out at global vaccine inequality, saying "the ongoing vaccine crisis is a scandalous inequity that is perpetuating the pandemic".

According to the WHO, more than 75 percent of all vaccines have been administered in just 10 countries.

"There is no diplomatic way to say it: a small group of countries that make and buy the majority of the world's vaccines control the fate of the rest of the world," he said.

He expressed that the number of doses administered globally so far would have been enough to cover all health workers and older people if they had been distributed equitably. "We could have been in a much better situation," he said.

The WHO chief said that countries that vaccinate children and other low-risk groups now do so at the expense of health workers and high-risk groups in other countries.

He also pointed out that the number of doses available for COVAX, the global initiative for equitable distribution, remains "vastly inadequate".

Tedros called on member states to support a massive push to vaccinate at least 10 percent of the population of every country by September, and to achieve another goal of vaccinating at least 30 percent by the end of the year.

"This is crucial to stop severe disease and death, keep our health workers safe and reopen our societies and economies," he said.

At the G20 Global Health Summit on Friday, Kristalina Georgieva, managing director of the International Monetary Fund, or IMF, proposed to vaccinate 40 percent of the world's population by the end of this year, and 60 percent by mid-2022.

Tedros said that the WHO is talking with the IMF, member states and partners, about how to achieve the "ambitious targets".

United Nations Secretary General Antonio Guterres has also warned of the dangers of a two-speed global response.

"Sadly, unless we act now, we face a situation in which rich countries vaccinate the majority of their people and open their economies, while the virus continues to cause deep suffering by circling and mutating in the poorest countries," he said.

"We are at war with virus. We need the logic and urgency of a war economy, to boost the capacity of our weapons," Guterres said.

He called for at least a doubling of manufacturing capacity by exploring all options, from voluntary licenses and technology transfers, to patent pooling and flexibility on intellectual property rights.

"I am ready to mobilize the entire United Nations system to support this effort," he said.

South Africa's President Cyril Ramaphosa also called for the huge divide in vaccination to be corrected.

"This is not only a moral imperative. Effective and comprehensive global vaccination is vital to ending the pandemic," he said.

Germany's Chancellor Angela Merkel noted that the pandemic reminds the world how important international cooperation is. She raised the idea of a "global health threat council" to improve prevention and responses to future pandemics.

"We have to have institutions that are up to the task, that meet our ambitions," added France's President Emmanuel Macron.

On Monday, the 74th World Health Assembly, or WHA, approved a recommendation by its general committee not to include the proposal by a few countries for Taiwan to be an observer in the WHA agenda.

Chen Xu, China's permanent representative to the UN Office at Geneva and other international organizations in Switzerland, said that Taiwan is an inalienable part of China, and the Taiwan-related proposal is in violation of the purposes and principles of the UN charter, runs against the WHO's constitution and the WHA's rules of procedure, and is illegal and invalid.

"The Taiwan region's participation in the WHA must be handled in accordance with the one-China principle," Chen said.