The Kentucky Republican took to Twitter on Tuesday with some statistics on the contagion's delta strain, which originated in India.

"Don't let the fearmongers win," Mr. Paul told his 3.2 million followers. "New public England study of delta variant shows 44 deaths out of 53,822 (.08%) in unvaccinated group. Hmmm."

Mr. Paul's tweet follows a video message by Dr. Anthony Fauci on the issue that President Biden shared on June 24.

"Here's the deal: The Delta variant is more contagious, it's deadlier, and it's spreading quickly around the world — leaving young, unvaccinated people more vulnerable than ever," Mr. Biden tweeted in conjunction with the NIAID director's commentary. "Please, get vaccinated if you haven't already. Let's head off this strain before it's too late."

Los Angeles County answered the president's call, for example, by urging citizens to wear masks inside, even if they are fully vaccinated.

"With increase circulation of the highly transmissible delta variant, the Los Angeles County of Public Health (Public Health), strongly recommends everyone, regardless of vaccination status, wear masks indoors," health officials said in a statement released Monday.

Mr. Paul has been a consistent critic of Dr. Fauci and has insisted that he's been correct "all along" regarding his handling of the pandemic.

"As you can see, emails that have been released now under Freedom of Information Act show two very important things: Fauci has been lying. I've been right all along," the senator recently wrote in an email to supporters.