US President Trump formally starts withdrawal from World Health Organization amid global coronavirus pandemic

"Congress received notification that POTUS officially withdrew the US from the @WHO in the midst of a pandemic," Senator Robert Menendez, the top Democrat on the Foreign Relations Committee, wrote on Twitter.

The United States is the largest financial contributor to the WHO - which leads the fight on global maladies from polio to measles to mental health - but it has increasingly been in Trump's crosshairs as the coronavirus takes a heavy toll.

After threatening to suspend the $400 million in annual US contributions and then announcing a withdrawal, Trump has formally informed UN Secretary-General Antonio Guterres that he has started the US pullout, a State Department spokesperson said.

The withdrawal is effective in one year - July 6, 2021 - and Joe Biden, Trump's presumptive Democratic opponent, is virtually certain to stop it and stay in the WHO if he defeats Trump in the November election.

Stephane Dujarric, the spokesman for Guterres, confirmed that the United States gave its notice.

Under conditions set when the United States entered the World Health Organization in 1948, Washington has to give a one-year notice to pull out - and meet its remaining assessed financial obligations, Dujarric said.

"To call Trump's response to Covid chaotic and incoherent doesn't do it justice," said Senator Robert Menendez, the top Democrat on the Foreign Relations Committee, who said that Congress was notified.

"This won't protect American lives or interests - it leaves Americans sick & America alone," he said.

Trump has accused the World Health Organization of bias toward China, saying it ignored early signs of human-to-human transmission of the deadly virus.

While many public health advocates share some criticism of the WHO, they question what other powers the world body had other than to work with China, where Covid-19 was first detected late last year.

Critics say Trump is seeking to deflect criticism from his own handling of the pandemic in the United States, which has suffered by far the highest death toll of any nation.

America has fared exceptionally poorly in its handling of the pandemic, with more than 130,000 people losing their lives, the highest death toll in the world by far.

The US is currently testing some 600,000 people a day, according to the Covid Tracking Project, but even this is deemed insufficient by health experts because of the very high rate of positive cases being found.

On Monday, the country's top infectious diseases expert said the country is still "knee-deep" in its first wave of coronavirus infections and must act immediately to tackle the recent surge.

Anthony Fauci said the number of cases had never reached a satisfactory baseline before the current resurgence, which officials have warned risks overwhelming hospitals in the country's south and west.

"It's a serious situation that we have to address immediately," Fauci said in a web interview with National Institutes of Health director Francis Collins.

But Fauci added he did not strictly consider the ongoing rise in cases a "wave."

"It was a surge or a resurgence of infections superimposed upon a baseline," he said.

"If you look at the graphs from Europe, the European Union as an entity, it went up and then came down to the baseline. Now they're having little blips, as you might expect, as they try to reopen. We went up, never came down to baseline, and now we're surging back up."

The death toll from the virus in the US hit 130,000 Monday, according to a tally by Johns Hopkins University, and the number of infections is nearing three million.

A worrying number of new cases were reported amid a resurgence that has forced several states to suspend phased economic reopenings.

Read also: US ends emergency authorization of hydroxychloroquine for Covid-19

Fauci, who heads America's National Institute of Allergy and Infectious Diseases, is a leading member of President Donald Trump's coronavirus task force and has become a trusted face in the administration's battle against the epidemic.

The US is the world's hardest-hit nation from the virus and has been struggling to come to grips with a new normal of social distancing and mask-wearing.

Officials have warned that some of the country's hospitals are in danger of being overwhelmed by the influx of COVID-19 patients.

Hospital beds are full in parts of Texas, while calls for fresh stay-at-home orders are growing.

Some mayors have said their cities reopened too early as Trump tries to downplay the severity of the crisis, prioritizing economic reopening instead.

On Tuesday, authorities announced free Covid-19 testing to people without symptoms to stem a surge of cases in three southern hotspots.

Five thousand tests per day will be offered in Jacksonville, Florida; Baton Rouge, Louisiana; and Edinburg, Texas.

This will continue for between five to 12 days.

The Department of Health and Human Services said testing is available to anyone aged five and over "including those experiencing symptoms; those who believe they may have been exposed to someone with Covid-19 coronavirus; and anyone who is worried about possibly having the virus."

In the south, the positivity rate has soared to 12 percent even as testing increases - which implies the virus is spreading rampantly.

Forty of the country's 50 states are seeing a rising case load.

Agencies contributed to this report.

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