The USA hit the latest bleak milestone Thursday in the historic pandemic: 4 million confirmed cases of infections.

Experts agree the number of cases is actually much greater – potentially 10 times higher than what’s been reported, according to federal data.

More than 143,000 people have died from the coronavirus in the USA, which leads the world for most cases and deaths.

“We are still knee-deep in the first wave of this,” Anthony Fauci, the nation’s top infectious disease expert, said in a Facebook Live interview July 6. “And I would say, this would not be considered a wave. It was a surge or a resurgence of infections superimposed upon a baseline.”

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USA TODAY has tracked the nation’s successes, setbacks and major news since the first case was confirmed in January in Washington state. Below, we break down the milestones in case and death counts:

July 23: USA reaches 4 million cases

The USA surpassed 4 million infections Thursday, doubling its total case count in a little more than a month. The death toll approached 144,000.

Though there’s more COVID-19 testing than ever, it’s created a bottleneck for labs and states bidding against each other for limited supplies. Experts said many tests become irrelevant after delayed results and increase the chance of the virus’s spread.

June 11: USA confirms 2 million cases

In early June, cases reached 2 million, 45 days after confirmed infections surpassed 1 million.

More than a dozen states and Puerto Rico saw cases spike at a faster rate in summer months. Experts said the unexpected uptick in cases could be due to lifting restrictions, isolated outbreaks and the virus catching up to communities that had not been affected.

May 27: US death toll passes 100,000

On May 13, data compiled by Johns Hopkins University showed the national curve flattening. Starting May 18, several states began to lift their restrictions, then Memorial Day saw more travel, busy beaches and pool parties.

The result: Deaths from the coronavirus surpassed 100,000.

According to polls, half of Americans said they were unsure they would get a vaccine.