WASHINGTON: US President Joe Biden on Wednesday slammed "Neanderthal" decisions to drop mask-wearing mandates in Texas and Mississippi, even as Covid-19 continues to rage worldwide, with Brazil hitting record deaths.

Moves by the two US states to defy federal guidelines and ditch mask requirements reflect local frustration with restrictions when Covid-19 caseloads are declining in the United States and vaccine distribution is accelerating.

Similar unrest is widespread in Europe, where the Swiss government said a referendum would be held in June on the legality of government powers to order lockdowns.

In the Dutch town of Bovenkarspel, a suspected bomb went off at a coronavirus testing center, breaking windows but not causing any injuries. Officials called the explosion, which was still under investigation, "a cowardly act of destruction."

The Netherlands has been shaken by riots against coronavirus curfews and the torching of another testing center in January.

Biden is touting a surge in vaccine production in the United States and says that by May, there will be enough supply for everyone in the country -- although it could take months more for the whole population actually to receive the shots.

But in the White House, he told reporters that this is no time to relax. More than half a million Americans have died from the coronavirus, and the toll ticks upward daily.

The Texas and Mississippi decisions were "a big mistake," he said.

"The last thing we need is Neanderthal thinking that in the meantime, everything's fine -- take off your mask, forget it. It still matters."

Rochelle Walensky, the director of the Centers for Disease Control and Prevention (CDC), echoed the warning, saying, "Now is not the time to release all restrictions."

"The next month or two is really pivotal in terms of how this pandemic goes."