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Asked if he had a message to Texas and Mississippi, Biden told reporters: "I think it's a big mistake. Look, I hope everybody's realized by now, these masks make a difference."
Biden said the increasing availability of vaccinations was making a difference in containing the Covid-19 pandemic, but it was critical to remain vigilant about wearing masks, washing hands and maintaining social distancing.
"The last thing, the last thing we need is Neanderthal thinking that, 'In the meantime, everything's fine, take off your mask, forget it.' It still matters," Biden said before a brainstorming meeting with Republican and Democratic lawmakers to address cancer.
Biden said over 511,000 people had died of the disease in the United States, and it would take time until everyone eligible was vaccinated.
Cases of Covid-19 in the United States remain upwards of 50,000 daily even after the US government has distributed more than 100 million vaccine doses and put shots into over 50 million arms, according to federal data.
"It is critical, critical, critical, critical, that they follow the science: Wash your hands, Hot water, Do it frequently. Wear a mask and stay socially distanced. I know you know that. I wish the heck some of our elected officials would."
Texas Governor Greg Abbott issued the most sweeping rollback of coronavirus restrictions of any US state on Tuesday, lifting a mask mandate and saying most businesses may open at full capacity next week.
Mississippi Governor Tate Reeves on Tuesday also lifted state-imposed mask mandates across Mississippi and removed Covid-19 related restrictions on business operations.
White House senior adviser Andy Slavitt told reporters earlier the federal government is planning to spend $100 million to help the joint partnership between Merck & Co and rival Johnson & Johnson announced on Tuesday accelerate vaccine production.
The infusion will help J&J ramp up production of its one-shot vaccine, Slavitt said.
J&J was contracted to deliver 200 million doses to the federal government by the end of May and roughly a billion doses globally by end-2021.
"Over time we believe Merck will be able to double the capacity of Johnson & Johnson," Slavitt said.
Biden said on Tuesday the United States will have enough vaccine supply to inoculate all adults by May.
J&J, Pfizer Inc, and Moderna Inc are contracted to deliver 700 million doses by mid-year between them.