CNN  — 

Covid-19 deaths have been falling dramatically in the US, but – with many people still unvaccinated – the number of daily deaths remains in the hundreds. And the groups most at risk are increasingly younger people and Black Americans.

Throughout the pandemic, Black people have been disproportionately affected by Covid-19, accounting for about 12.5% of the population but more than 15% of total deaths, according to data from the US Centers for Disease Control and Prevention. In May, that percentage went up to 19%.

Recently, the average age of people dying from the virus also shifted younger. Adults under the age of 40 represented about 3% of Covid-19 deaths in May, more than double their share of total deaths since the pandemic began.

Health experts have been conscious of disparity of vaccine accessibility for much of the time they have been available. Now, vaccines have demonstrated high enough protection against severe disease for the CDC director to call most new Covid-19 deaths “entirely preventable” – even as the dangerous Delta variant is on the rise.

Officials are hoping to pick up the slowing vaccination rates by reaching people who are hesitant because of misinformation, unmotivated because they believe they are not at risk or unable to get vaccinated because they lack the technology or community access.

“As more Americans have rolled up their sleeves to get vaccinated, we have chipped away at the ability of the Covid-19 virus to cause more illness and more suffering,” Dr. Rochelle Walensky, director of the CDC, said Tuesday.

“This new virus forced too many of our families to accept death as its outcome for too many of our loved ones, but now, this should not be the case.”

Benefits of vaccination outweigh risk of myocarditis

Some fears surrounding getting inoculated against the virus involve reports of heart inflammation, but CDC researchers say the benefits of the vaccines far outweigh the risks.

The US Food and Drug Administration expects to add a warning about the risk of myocarditis and pericarditis to information sheets for Covid-19 mRNA vaccines, an FDA official said Wednesday.

Myocarditis results from inflammation of the heart muscle and pericarditis is inflammation of tissue surrounding the heart.

For every million second-dose vaccinations, there may be tens of myocarditis cases, CDC researchers told the agency’s Advisory Committee on Immunization Practices during a virtual meeting.

On the other hand, for every 1 million second-dose vaccinations, 5,700 Covid-19 cases, 215 hospitalizations, 71 intensive care unit admissions and two deaths would be prevented, the data show. It’s estimated there might be 56 to 69 myocarditis cases.

People who do experience myocarditis after receiving the vaccine often quickly recover, Dr. Matthew Oster, a pediatric cardiologist, told the committee.

Although reduced heart function can occur in someone with myocarditis, “the good news so far is that that function tends to rebound rather quickly” in cases following vaccination, said Oster, a member of the CDC Covid-19 Vaccine Task Force.

He emphasized that in most cases, “there’s typically quick resolution,” but long-term data are still needed.

Following the committee’s discussion, an unusual alliance of government and health agencies and groups signed a joint statement endorsing vaccination.

“As physicians, nurses, public health and health care professionals, and, for many of us, parents, we understand the significant interest many Americans have in the safety of the COVID-19 vaccines, especially for younger people,” the long list of medical groups said in a joint statement. “The facts are clear: this is an extremely rare side effect, and only an exceedingly small number of people will experience it after vaccination.”

CDC watching infections to decide on boosters

With variants increasing as the virus continues to spread, some experts have worried that there will come a point when the current vaccines can no longer fight the variants that have developed. Researchers say boosters to the vaccine could be the answer.

“We, in an interagency way, are planning to boost,” Walensky said during the Milken Institute Future of Health Summit on Wednesday. “Because, quite honestly, we want to make sure that if we see more disease out there, we have a mechanism, we’re fully ready to combat it.”

Researchers at the CDC are closely monitoring data to consider whether Covid-19 vaccine booster shots may be needed in the future – especially for at-risk groups.

Those include residents of long-term care facilities, adults 65 and older, health care personnel and immunocompromised patients.

The information that would help researchers decide if boosters are necessary and who would get them could come in part from a rise in so-called breakthrough cases, federal vaccine advisers said.

“We really, truly need to wait for more data,” ACIP member Dr. Sharon Frey said at the meeting. “I think the only thing we can do at this moment is, if we start to see an uptick in reinfections in people, or new infections in people who have been vaccinated, that’s our clue that we need to move quickly.”

CNN’s Deidre McPhillips, Jacqueline Howard, Maggie Fox, Jamie Gumbrecht and Naomi Thomas contributed to this report.