Average Covid-19 cases are the lowest they’ve been in nearly a year. Vaccines can push them even lower, officials say

His comments come as state leaders and public health officials express optimism about the country’s Covid-19 trends and where we could be by summer.

In Maryland, Gov. Larry Hogan said Tuesday the state’s seven-day positivity rate had dropped to the lowest level since the pandemic’s start. In California, Gov. Gavin Newsom announced three new Covid-19 deaths Tuesday, the state’s lowest daily number in the pandemic.

In the past week, the US has averaged around 31,200 new Covid-19 cases — the lowest average since last June and less than half what the average was just a month ago, according to Johns Hopkins University data.

And the country averaged 614 Covid-19 deaths daily over the last week — less than a third of the 1,988-per-day average seen three months ago, according to Johns Hopkins data.

Still, among the messages of hope, officials and medical experts are offering an important reminder: It’s not over just yet.

“Cases are going down, deaths are going down, hospitalizations are going down, vaccinations are going up,” Dr. William Schaffner, an infectious diseases professor at Vanderbilt University, told CNN on Tuesday. “If the vaccinations increased even more rapidly, you would see those other metrics, those Covid metrics, going down even more.”

“There’s still lots of people out there who haven’t come forward and rolled up their sleeves, we need them to do that,” he added. “Vaccine in the refrigerator cannot prevent disease.”

A Covid-19 vaccine booster, when authorized, will likely be needed within a year following initial vaccination, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, said in an Axios interview posted Wednesday.

“We know that the vaccine durability of the efficacy lasts at least six months, and likely considerably more, but I think we will almost certainly require a booster sometime within a year or so after getting the primary,” Fauci said.

Pfizer CEO Albert Bourla, citing data he’s seen, told Axios that Pfizer vaccine recipients may need a booster “between eight and 12 months” after their second shot.

Pfizer has not finished its trials on a booster.

“I believe in one, two months, we will have enough data to speak about it with much higher scientific certainty,” Bourla said.

The pace of vaccinations has drastically slowed from just a few weeks ago, and officials say it’s crucial to keep getting more shots into arms.

The US averaged about 1.77 million Covid-19 vaccine doses a day across the past week — well off the peak average of about 3.3 million in mid-April, according to CDC data.

“We’ll need to focus even harder on meeting people where they are,” White House Covid-19 Response Team senior adviser Dr. Marcella Nunez-Smith said during a Tuesday briefing. “And we’ll continue providing the public with the answers they need to get vaccinated.

“We know we must push further.”

Outreach efforts, she said, have included targeting resources to the highest-risk and hardest-hit communities, conducting federally run vaccination sites and setting up mobile vaccination clinics.

Where people are being vaccinated, the inoculations appear to be having an impact. Over the past week, states with higher vaccination rates have generally had lower Covid-19 case rates, a CNN analysis published Wednesday shows.

Uneven vaccination rates are worrying experts, in part because the more opportunity people give to the virus to spread, the more chance it has to morph into new variants.

If a variant is resistant to the vaccine, that “could be problematic even for those who are vaccinated,” Dr. Paul Offit, an infectious disease expert at the University of Pennsylvania, said.

“I think we need to fix this,” said Offit, a member of the US Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee. “We need to impress on people the importance of vaccination to stop the virus.”

But the sudden guidance change left many Americans confused and some state and local leaders at odds about the best way to move forward while a big part of the country remains unvaccinated.

In Maryland, the governor announced the end of a statewide mask mandate last week, but Baltimore city health officials said a local mandate would remain in place until at least 65% of adults in Baltimore receive at least one Covid-19 vaccine dose.

New York City Mayor Bill de Blasio said Wednesday that, as a vaccinated person, whether he wears a mask in places where he’s not required will depend on if he is unsure about the vaccination status of people around him.

“When in doubt, wear a mask. … That’s the approach I’m going to take,” de Blasio said.

In Texas, Gov. Greg Abbott issued an executive order Tuesday prohibiting state governmental entities such as cities, counties, school districts, public health authorities and government officials from requiring mask wearing.

Some local leaders disagreed with Abbott’s move.

“If you are a city of Houston employee or entering a city facility and you have not been fully vaccinated, you should wear your mask,” Houston Mayor Sylvester Turner said in a statement posted on Twitter. “We are not mandating it, but I strongly encourage everyone to get vaccinated to protect themselves, their family and their co-workers.”

Some experts have warned that lifting mask mandates now could lead to some unvaccinated Americans shedding their masks too, and leave the country relying on a kind of honor system.

Fauci told Axios that he believes unvaccinated people were misinterpreting the CDC’s masking guidance, mistakenly believing it applied to them.

“I think people are misinterpreting — thinking this is a removal of a mask mandate for everyone. It’s not,” he said, according to Axios.

Since there is no vaccine for children under 12, the American Academy of Pediatrics (AAP) recommended Wednesday that children and adults who are not yet fully vaccinated against Covid-19 still wear masks in certain settings.

Children should continue wearing masks in public places as they have throughout the pandemic, particularly when social distancing isn’t possible, said Dr. Yvonne Maldonado, chair of the AAP’s Committee on Infectious Diseases. Children can take off their masks when they are with family members from the same household or at small gatherings with full vaccinated family members and friends.

Children can also take off their masks during water sports, like swimming, or activities that could pose a safety risk, like gymnastics, Maldonado said.

CNN’s Jen Christensen, Naomi Thomas, Ashley Killough, Jason HannaDeidre McPhillips, Elizabeth Cohen, Raja Razek, Christina Walker and Stella Chan contributed to this report.