(CNN) The nation's top infectious disease expert says vaccine mandates work and they'll help get more people vaccinated against Covid-19.
About a quarter of the eligible US population remains unvaccinated against coronavirus and the rate of people getting booster shots is now outpacing the rate of people getting their first doses.
Dr. Anthony Fauci told CNN's Wolf Blitzer on Monday that the federal government is trying to persuade people to get vaccinated on their own, but some may need to be required.
"We've obviously been trying very hard," Fauci said. "We try to get trusted messengers out there and try and get this away from being an ideological or political statement, get back into the realm of pure public health, and try to convince people."
Fauci said he and fellow heath officials don't like to tell people what they need to do with regard to vaccines.
"But we know that mandates work," he said.
Fauci, the long-time director of the National Institute of Allergy and Infectious Diseases, said there is evidence that mandates are working in academic settings and at corporations such as airlines.
"So, although you'd like people to do it on their own accord, sometimes mandates actually can help in that regard -- as sensitive an issue as that is, it is really getting people more vaccinated," he said.
The best way for the US to assure that a decline in cases, hospitalizations and deaths will continue is to get "a lot more" people vaccinated, he added.
Fauci said if most of the people who haven't gotten shots do get vaccinated he is confident there won't be another surge in cases.
The number of Americans getting a dose of Covid-19 vaccine has jumped to about 1 million a day, according to data this past week from the Centers for Disease Control and Prevention.
New cases are declining, with about 93,814 infections reported each day this past week, according to data from Johns Hopkins University. Daily Covid-19 deaths are slowly decreasing, with an average of 1,692 deaths per day.
And the US Food and Drug Administration will consider whether to authorize an antiviral pill to treat Covid-19.
But there is some bad news: The highly contagious Delta variant is not done. And cooler weather may drive more transmission as people spend more time indoors, health experts say.
"You're starting to see an uptick in cases in the colder parts of the country and as people are driven indoors without masks on," former FDA Commissioner Dr. Scott Gottlieb said Monday.
In five states, new Covid-19 cases jumped more than 10% this past week compared to the previous week. Most of them are in colder states: Montana, Colorado, Minnesota, Michigan and Vermont.
"The Delta wave has not run through the United States," Gottlieb said. "I think we have a couple of months to go."
And that means it's too early to tell what the holidays will look like.
"I think some families will have to exercise more caution than others," Gottlieb said, especially those with children who might be too young to get vaccinated.
Outdoor trick-or-treating may be one of the safer holiday activities this season -- but it's important not to be careless, doctors say.
"If you live in an area with individual houses or townhomes, I think it's probably ... low risk to knock on people's doors and trick-or-treat. Just make sure not to step inside someone's house," CNN medical analyst Dr. Leana Wen said.
"If you live around a lot of apartment blocks and have to enter elevators and hallways to trick-or-treat, the Covid-19 risk is significantly higher," she said.
"I'd encourage parents not to enter other people's apartment buildings and instead look for activities in a neighboring park or other primarily outdoor settings."
And this is not a good year for indoor Halloween parties if children are unmasked and unvaccinated, said Dr. Megan Ranney, associate dean of the School of Public Health at Brown University.
While children may be less likely to suffer severe illness or death from Covid-19 compared to adults, they aren't immune to serious effects.
The FDA is considering a request from Pfizer to authorize its Covid-19 vaccine for children ages 5 to 11. The dosage would be one-third the amount used by teens and adults.
On October 26, the FDA's independent vaccine adviser -- the Vaccines and Related Biological Products Advisory Committee -- will meet to discuss pediatric vaccines.
If the FDA and CDC sign off, it's possible children in that age group could get their first doses by the end of this month or early November. But just like with adults getting the Pfizer vaccine, they wouldn't be fully vaccinated until two weeks after their second dose.
Gottlieb, who's now a Pfizer board member, said he believes children ages 2 to 4 might not become eligible to get vaccinated until early 2022.
"Previously we had talked about trying to have that (trial) data available before the end of this year, which could have prompted an authorization perhaps by the end of the year, at least in kids ages 2-4," Gottlieb told CBS on Sunday.
"I think that it's more likely that it slips into the first quarter of next year at the very least, but not too far into next year."
Gottlieb told CBS he plans to vaccinate his own young daughters.
"There's a lot of parents like me that, as soon as the vaccines available for their children, are going to go out and get their kids vaccinated," he said. They "see the benefits of vaccination."