Originally Published: 17 OCT 21 05:29 ET

Updated: 18 OCT 21 02:18 ET

By Aya Elamroussi, CNN

(CNN) -- The rates of Covid-19 cases, hospitalizations and deaths are improving; an optimistic sign for the future of the pandemic. But with so many Americans still unvaccinated, the numbers could still go back up, Dr. Anthony Fauci told Fox News Sunday.

"If we don't do very well in that regard, there's always the danger that there will be enough circulating virus that you can have a stalling of the diminishing of the number of cases and when that happens, as we've seen in the past with other waves that we've been through, there's the danger of resurgence," said Fauci, the director of the National Institute of Allergy and Infectious Disease and chief medical adviser to President Joe Biden, who appeared on Fox News Sunday with Chris Wallace.

Although cases still remain high at an average of more than 85,000 infections a day, they are down by more than 8,000 from the weeks before, according to data from Johns Hopkins University. And deaths are down an average of more than 200 a day from the start of the month.

Progress in the numbers is still threatened, however, by the low rates of vaccination. As of Sunday, 57% of the total population was fully vaccinated against the virus, according to the US Centers for Disease Control and Prevention.

And though health experts do not know exactly what proportion of the population needs to be protected to control the spread of the virus, Fauci has said a vast majority will need to be vaccinated.

The good news is, Fauci does not think another spike in cases is inevitable.

"It's going to be within our capability to prevent that from happening," said Fauci. "The degree to which we continue to come down in that slope will depend on how well we do about getting more people vaccinated."

Johnson & Johnson boosters

As more Covid-19 boosters are potentially set to become available, experts say those who received the Johnson & Johnson one-dose vaccine are "awfully well protected," but should still get another shot for maximum safety.

"The Johnson & Johnson vaccine turns out not to be quite as effective as the Pfizer and Moderna. And people who got (the J&J vaccine) way back at the beginning of this year therefore have been somewhat less protected, although they're still awfully well protected," said Dr. Francis Collins, director of the National Institutes of Health.

Collins' remarks come after a US Food and Drug Administration (FDA) advisory committee recommended all adults who received the single-dose Johnson & Johnson shot should get a second dose at least two months after their first dose.

The FDA will consider the committee's advice. Then the CDC's vaccine advisers will be asked to consider it.

Experts are advising people who received the Johnson & Johnson vaccine should get a booster shot as soon as it is available because it will provide them with the best protection against Covid-19, especially as the more transmissible Delta variant continues to be the dominant strain in the United States. But they are also reinforcing the point the vaccine remains highly effective against the worst consequences of the virus.

Johnson & Johnson has indicated its vaccine immunity has waned -- but not by much. Still, the company said studies show a booster dose increases protection equivalent to the 94% efficacy shown by the Moderna and Pfizer mRNA vaccines soon after they were first given in clinical trials last year.

Meanwhile, various real-world studies suggest Johnson & Johnson's vaccine was anywhere between 50% and 68% effective, Dr. Amanda Cohn with the CDC said Friday.

"If the mRNA vaccines from Pfizer and Moderna had not been so utterly, amazingly effective, 95%, then Johnson & Johnson would look like a hero with their one dose, but I guess our standards are being set awfully high here by the other vaccines," Collins told CNN.

But a study published Thursday reported a steep decline in vaccine effectiveness against infection by August of this year, especially for people who received the J&J vaccine.

Researchers found among more than 600,000 veterans, J&J's vaccine's protection against infection fell from 88% in March to 3% in August. Meanwhile, Moderna's vaccine protection against infection fell to 64% from 92%, and Pfizer's declined to 50% from 91% during the same time period.

"The performance of these vaccines against severe disease, keeping people out of the hospital, is distinctly better than that, and that's the main thing we're interested in," said Dr. William Schaffner, a professor in the Division of Infectious Diseases at Vanderbilt University Medical Center in Nashville.

The FDA vaccine advisory committee also supported emergency use authorization for booster shots of Moderna's Covid-19 vaccine after six months, but not for everyone. Moderna recipients over the age of 65 and adults with conditions that put them at risk for severe disease or who work or live in a place which puts them at higher risk of complications or severe illness may be eligible for the 50-microgram booster, which is half the size of the primary two-dose series.

And as for whether booster shots will become available for everyone who's already vaccinated, health officials are still working to determine that.

"I think as more data come in and ... are carefully reviewed and vetted, then I think the expansion of the recommendations may be in order. Not quite yet," Schaffner said.

Minnesota Emergency and Urgent Care services suspended over nurses strike

In many places, the brunt of the hospital strain from Covid-19 has fallen on nurses, and a strike in Minnesota has impacted services.

Emergency and Urgent Care services have been temporarily suspended at Abbott Northwestern WestHealth in Plymouth, Minnesota due to about 50 nurses from the Minnesota Nurses Association (MNA) choosing to strike, according to a statement from Allina Health.

The nurses are striking to seek "a contract that provides fair pay and benefits to nurses on the frontlines of the Covid-19 pandemic," the MNA said in a statement on Thursday.

"MNA nurses have been negotiating a new contract for months, but Allina has refused to agree to fair pay for holiday work or adequate benefits," the MNA said in the statement. "Compensating nurses fairly for holiday work is especially critical because understaffing by Allina and other hospital systems has required nurses to work more days and longer hours, including overtime and holidays, as they continue on the frontlines of the COVID-19 pandemic."

The closure began Sunday morning and will last until 7:00 a.m. local time on Wednesday, according to the statement.

"Allina Health and Abbott Northwestern WestHealth have negotiated 7 times with MNA. A contract settlement was previously reached and unanimously recommended by the union's bargaining team. Unfortunately, the MNA could not finalize that agreement," Allina Health's statement says. "Throughout negotiations, we have consistently offered proposals that demonstrate our commitment to our employees, including an immediate wage increase to align wages with other metro hospitals and agreeing to some of the union's other priority issues."

Black people represent a larger share of new vaccinations

As public health officials talk boosters, 66 million Americans who are eligible for a vaccine still haven't received their initial shots, while nearly 57% of the US population is fully vaccinated, according to the CDC.

Black and brown communities have proven to be disproportionally bearing the brunt of the pandemic for various reasons, including health care inequities.

But there is some good news in terms of Black people's vaccination numbers. Recently, Black people -- who comprise 12.4% of the total US population -- have come to represent a slightly larger share of new vaccinations than in the past, according to the CDC.

Since vaccinations began, Black people in the US have accounted for 10.6% of all people with at least one dose. But in the past two weeks, they have accounted for 11.4% of new vaccinations.

The growth in vaccinations comes after two studies published by the CDC in April showed racial and ethnic minority groups had higher rates of hospitalization for Covid-19 and sought emergency department care for Covid-19 more when compared to White people.

Another analysis published earlier this month by the Kaiser Family Foundation (KFF) showed the difference in Covid-19 cases and deaths between Black, Hispanic and White people is narrowing.

KFF researchers found while disparities are still present across different racial groups, the gap is improving for Black and Hispanic people, based on an analysis of case and death data from CDC last month. But Covid-19 infections remain high in Native American and Alaska Native people.

Some in law enforcement are resisting vaccine, but Covid-19 is killing more of them than gunfire

Meanwhile, Covid-19 has become the leading cause of death for officers, despite law enforcement being among the first groups eligible to receive the vaccine at the end of 2020.

As of Saturday, the total stood at 476 Covid-19 related deaths since the start of the pandemic, compared to 94 from gunfire in the same period.

Still, law enforcement officers and their unions across the country have resisted vaccine mandates, despite the Delta variant-fueled resurgence of Covid-19 and effectiveness of the shots in preventing severe cases and death.

Reasons cited for the vaccine resistance among law enforcement officers range from disinformation to distrust in the science of the vaccines.

In Chicago, the head of the police union asked officers not to follow the mayor's order to submit Covid-19 vaccination proof by the Friday deadline.

John Catanzara, the Chicago Fraternal Order of Police president, urged, in a video message posted on YouTube, for officers to stand their ground against the mandate.

"I am telling you right now. It is an improper order. It is illegal ... Refuse that order," Catanzara said in the video.

The city filed a complaint alleging the union was "encouraging a work stoppage or strike." A Cook County Circuit judge ruled Friday night Catanzara should not make public statements encouraging members to not comply with the vaccination policy.

Catanzara "has never engaged in, supported, or encouraged a work stoppage," according to a union statement on Friday.

Lightfoot said the city would take the weekend to check with officers who have not complied with the mandate. She said officers should report for duty until they are told by supervisors they have been placed on leave.