Anthony Fauci has a reputation for plain speaking, as a senator who accused him of lying discovered to his cost on Tuesday. A congressional hearing on the coronavirus pandemic was electrified when Fauci, the nation’s top infectious diseases expert, clashed with Rand Paul, a Republican senator for Kentucky and longtime opponent of mask-wearing. Paul suggested that Fauci had lied before Congress in May when he denied that the National Institutes of Health (NIH) funded so-called “gain of function” research – the practice of enhancing a virus in a lab to study its potential impact in the real world – at a virology lab in Wuhan, China. “Dr Fauci, knowing it is a crime to lie to Congress, do you wish to retract your statement of May 11 where you claimed that the NIH never funded gain of function research in Wuhan?” the senator demanded. Fauci, speaking in his now instantly recognisable Brooklyn accent, fired back forcefully: “Senator Paul, I have never lied before the Congress and I do not retract that statement.” He also told the Senate health, education, labor, and pensions committee that a study cited by Paul referenced a different sort of virus entirely from the one responsible for the coronavirus pandemic. “This paper that you are referring to was judged by qualified staff up and down the chain as not being gain of function.” Paul interrupted, Fauci insisted “Let me finish,” but Paul went on, pointing his finger as the exchange became more heated. Fauci said angrily: “Senator Paul, you do not know what you’re talking about, quite frankly. And I want to say that officially. You do not know what you are talking about.” The sparring continued as the men repeatedly interrupted each other and the committee chairperson struggled to retain control. Fauci concluded: “If anybody is lying here, senator, it is you.” Critics say Paul is grandstanding for an audience on the right, where Fauci has become a boogeyman, targeted by media commentators and subjected to “Lock him up!” chants at Donald Trump’s rallies. The director of the National Institute of Allergy and Infectious Diseases has previously said he deals with such criticism partly by turning to Mario Puzo’s 1969 novel The Godfather with its philosophy: “It’s not personal, it’s strictly business.” Fauci also told Tuesday’s hearing that the Delta variant of the coronavirus was the cause of more than 80% of new US Covid-19 cases, but the authorised vaccines remain more than 90% effective in preventing hospitalizations and deaths. Biden in late May called on aides to investigate the origins of the virus and to report back to him within 90 days. The more prevalent theory is that the virus originated in animals, possibly bats, and was passed on to humans. Tina Smith, a Democratic senator for Minnesota, asked Fauci if there was anything else he would like to say to “counteract these attacks on your integrity that we’ve all just witnessed”. He responded: “This is a pattern that Senator Paul has been doing now at multiple hearings based on no reality. He was talking about gain of function, this has been evaluated multiple times by qualified people to not fall under the gain of function definition. I have not lied before Congress. I have never lied. Certainly not before Congress. Case closed.”