The next few weeks are critical to tamping down a disturbing coronavirus (COVID-19) surge, Dr. Anthony Fauci told the U.S. Congress on Tuesday — issuing a plea for people to avoid crowds and wear masks just hours before mask-shunning President Donald Trump was set to address a crowd of his young supporters in one hot spot.

Dr. Fauci and other top health officials also said they have not been asked to slow down virus testing, in contrast to Mr. Trump’s claim last weekend that he had ordered fewer tests be performed because they were uncovering too many infections. Mr. Trump said earlier on Tuesday that he wasn’t kidding when he made that remark. “We will be doing more testing,” Dr. Fauci, infectious disease chief at the National Institutes of Health, pledged to a House committee conducting oversight of the Trump administration’s response to the pandemic.

The leading public health officials spent more than five hours testifying before the committee at a fraught moment, with COVID-19 cases rising in about half the States and political polarisation competing for attention with public health recommendations.

Dr. Fauci told lawmakers he understands the pent-up desire to get back to normal as the U.S. begins emerging from months of stay-at-home orders and business shutdowns. But that has “to be a gradual step-by-step process and not throwing caution to the wind”, he said.

“Plan A, don’t go in a crowd. Plan B, if you do, make sure you wear a mask,” Dr. Fauci said.

Record surges

Troubling surges worsened on Tuesday in several States, with Arizona, California, Mississippi, Nevada and Texas setting single-day records for new COVID-19 cases, and some Governors saying they’ll consider reinstating restrictions or delaying plans to ease up in order to help slow the spread of the virus.

Arizona, where Mr. Trump was headed for a speech at a Phoenix megachurch, reported a new daily record of nearly 3,600 additional infections on Tuesday. Arizona emerged as a COVID-19 hot spot after Republican Governor Doug Ducey lifted his stay-home orders in mid-May. Last week, he allowed cities and counties to require masks in public places and many have done so.

Texas surpassed 5,000 new cases for a single day for the first time — just days after it eclipsed 4,000 new cases for the first time

Another worrisome trend — an increase in infections among young adults. Dr. Fauci said while COVID-19 tends to be less severe in younger people, some of them do get very sick and even die.

If people say, “’I’m young, I’m healthy, who cares’ — you should care, not only for yourself but for the impact you might have” on sickening someone more vulnerable, Dr. Fauci said.

About 2.3 million Americans have been infected and some 1,20,000 have died, according to data from Johns Hopkins University.