Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said a recent increase in coronavirus cases in a number of states is not necessarily a “second spike.”

“However, when you start to see increases in hospitalization, that’s a surefire situation that you’ve got to pay close attention to,” Fauci told CNN’s Wolf Blitzer in The Situation Room on Friday.

Fauci also said there may not be a so-called second wave of Covid-19 cases as some health experts are predicting.

“It is not inevitable that you will have a so-called ‘second wave’ in the fall, or even a massive increase if you approach it in the proper way,” he said.

He advised Americans to follow social distancing recommendations and to continue wearing masks in public, among other CDC guidelines.

Meanwhile former CDC Director Dr. Julie Gerbering, an infectious disease expert who currently is an executive vice president at Merck & Co Inc., said Friday that the industry’s collaborative efforts and the 130 vaccines in different stages of production points make her cautiously optimistic the pandemic will end with a vaccine.

“I think the science is on our side, but that doesn’t say anything about the speed, the safety, and the durability and all of the other criteria that have to come into play before we have something that we can count on to give us that population immunity,” Gerberding said.

There are plenty of roadblocks that can arise between lab testing and putting a product out into the public, she said.

“So a little scientific humility is also an important component of the communication,” she said.

The CDC released its latest versions of guidelines for people Friday with a reminder that the virus is still spreading. The guidelines reiterate the need to stay apart from others, wear a face covering, and try not to share objects.

They also warn that public transportation and travel can still be risky and people need to think twice before they leave home.