WASHINGTON (NEXSTAR) – At a United States Senate hearing Wednesday, Dr. Anthony Fauci made it clear he feels Americans will likely need to wear masks and stay socially distant to protect themselves even after a vaccine becomes available. He also pushed back firmly on criticism of New York’s handling of the pandemic from Republican senator Rand Paul of Kentucky.

Paul, an ophthalmologist prior to entering politics, said New York Governor Andrew Cuomo should not be lauded for his government’s response to COVID-19, stating “he had the highest death rate in the world.”

Fauci appeared prepared for this line of reasoning.

“You’ve misconstrued that senator, and you’ve done that repetitively in the past,” said Fauci, the director of the National Institute of Allergy and Infectious Diseases, pointing to the state’s recent one percent positivity rate as evidence that New York is properly testing and taking needed masking and social distancing precautions.

In the contentious exchange, captured on video, Paul says the low positivity rate may simply be due to community immunity developing in New York.

“This happens with Senator Rand all the time,” retorted Fauci. “You are not listening to what the director of the CDC said. That in New York it’s about 22 percent. If you believe 22 percent is herd immunity, I believe you’re alone in that.”

Fauci was attempting to drive home the message that immunity and even a vaccine won’t change the need to protect yourself overnight.

“The vaccine availability will go a giant step to controlling the infection, but you’re not going to completely eradicate it or eliminate it,” Fauci said.

It’s unusual for a vaccine to be 100% effective, he pointed out. Also, some people are skeptical of vaccinations and may avoid getting a shot.

Even if there’s enough vaccine available for the entire U.S. population, it will take time to distribute the shots.

Democratic senators also used the hearing to highlight the notion that COVID-19 is the newest pre-existing medical condition. That means people who had the disease could be denied health insurance if the Obama-era Affordable Care Act is overturned.

The death of Justice Ruth Bader Ginsburg means there are no longer five justices on the court who have previously upheld the Affordable Care Act. That law forbids insurers from turning down people with health problems or charging them more.

“Any diagnosis of COVID will likely become a pre-existing condition,” said Sen. Chris Murphy, D-Conn. “We will see rates skyrocket for anybody who has had COVID.”

Fauci told senators much remains unknown about the long-term consequences of COVID-19. Fauci called attention to the so-called “long haulers,” people who have recovered but continue to struggle with a range of symptoms, including pain and fatigue.

A “disturbing number” of recovered patients have inflammation of the heart in MRI exams, Fauci says.

Fauci said government scientists should know by the end of this year — November or December — whether any of the vaccines now in trial are safe and effective.

The Associated Press Contributed to this report.