New cases of Covid-19 are falling sharply in the US as millions of people are vaccinated every day. This fuels optimism that the nation may have averted the surge in infections in other parts of the world and is finally turning the corner for worse outbreaks worldwide.

As of Saturday, the 7-day average of daily new cases fell for the first time since October to below 50,000 and is down by 17% compared to the previous week. Hospital stays and deaths due to the disease are also decreasing.

The cases are falling as more Americans get vaccinated. To date, more than 100 million people in the U.S. have been fully immunized against Covid-19, according to the Centers for Disease Control and Prevention, or nearly a third of the population. Approximately 146 million people, or 44% of the population, have received at least one dose of vaccine.

Former Food and Drug Administration Commissioner Scott Gottlieb said Sunday that the steep decline in new Covid-19 cases in the US is likely to continue and predicted a “relatively calm summer in terms of the spread of coronavirus” .

“Look, the situation in the US continues to improve, and I think the decline in cases will accelerate in the coming weeks,” Gottlieb said on CBS News’ Face the Nation.

The doctor credited the mass vaccination campaign launched under President Donald Trump and continued under President Joe Biden to help stem the spread of the disease.

The rate of vaccine administration has declined slightly in the past few weeks after months of spike after receiving one for most of the people who were most likely to want a shot. However, Gottlieb said that continued vaccination, even in a slower location, will lower virus transmission.

“This was a monumental achievement – the introduction of this vaccine, the vaccination of so many Americans – and it will go on,” said Gottlieb. “We will keep working on it. The vaccination rate will slow down in the coming weeks. But we will continue to take in more people when we come into the summer.”

Dr. Anthony Fauci, the White House pandemic advisor, suggested last week that in a few weeks’ time he would expect “a significant reduction in the number of infections per day and a significant reduction in all parameters, namely hospitalizations and deaths.”

The CDC has revised its public health guidelines, stating that fully vaccinated people can attend small outdoor gatherings without a mask.

“Today is another day when we can take a step back to normal,” said CDC director Rochelle Walensky during a press conference on the announcement. “When you are fully vaccinated things are much safer for you than those who are not fully vaccinated.”

Celebrating the fall in cases, Biden predicted that Americans could potentially get together with friends and family to celebrate July Fourth.

“After a long, tough year, this will make this Independence Day very special – where we not only mark our independence as a nation, but also begin to mark our independence from this virus,” he said in March.

Cities and states have moved in different paces in response to advances in controlling the spread of Covid-19. New York City Mayor Bill de Blasio said he intends to fully reopen the city on July 1. A prospect some experts thought plausible, while Governor Andrew Cuomo said he hoped the city could open even sooner.

Optimism has spread to the stock market, where US indices have hit near record highs.

To get a feel for what might be coming up for the US, Gottlieb said it might be helpful to check out heavily vaccinated San Francisco.

“About 71% of the people in San Francisco had at least one dose of the vaccine, 47% were fully vaccinated. They record about 20 cases a day. You have about 20 people hospitalized,” Gottlieb said.

“They have dramatically reduced Covid in this city and it is largely the result of vaccinations,” he added.

From a financial point of view, Gottlieb suggested that the profits from vaccination were “stalled” and “fairly sustainable”.

“We are entering warm months in which this will create a setback against the spread of the coronavirus, and we are securing these profits,” said Gottlieb.

Even if the health situation in the USA is on the verge of normal, it is deteriorating in other countries with fewer resources. In India, the new daily cases exceeded 400,000 on Saturday, a record.

Disclosure: Scott Gottlieb is a CNBC employee and a member of the boards of directors of Pfizer, genetic testing startup Tempus, health technology company Aetion Inc., and biotech company Illumina. He is also co-chair of the Healthy Sail Panel for Norwegian Cruise Line Holdings and Royal Caribbean.

Subscribe to CNBC Pro for the live TV stream, deep insights and analysis of how to invest over the next president’s term.