Advisers to the Centers for Disease Control and Prevention are scheduled to meet on Wednesday to address reports of rare heart problems in young people immunized with the coronavirus vaccines made by Pfizer-BioNTech and Moderna.

The reports involve conditions called myocarditis, inflammation of the heart muscle; and pericarditis, inflammation of the membrane surrounding the heart. Most cases have been mild, with symptoms like fatigue, chest pain and disturbances in heart rhythm that quickly clear up. The agency is tracking nearly 800 reports, although not all have definitively been linked to the vaccines.

The C.D.C. advisers’ meeting comes as the Biden administration publicly acknowledges that it expects to fall short of its goal of getting 70 percent of Americans partly vaccinated by July 4. The shortfall, officials said on Tuesday, results in part from reluctance among younger Americans to be immunized.

Experts have said that the benefits of immunization far outweigh the risk of the possible problems, but they are expected to revisit that debate, particularly for adolescents and young adults.

More than half of the heart problems were reported in Americans ages 12 to 24, while that age group accounted for only 9 percent of the millions of doses administered. The numbers are higher than would be expected for those ages.

As of May 31, 216 people had experienced myocarditis or pericarditis after one dose of either vaccine, and 573 after the second dose. While most cases were mild, 15 patients remained in hospitals at that time. The second dose of the Pfizer-BioNTech vaccine was linked to about twice as many cases as the second dose of the vaccine made by Moderna.

“We look forward to more clarity regarding the potential risk of myocarditis after mRNA vaccines to increase vaccine confidence and vaccination rates,” said Dr. Yvonne Maldonado, chair of the Committee on Infectious Diseases at the American Academy of Pediatrics.

Recommendations from the C.D.C. advisers after Wednesday’s meeting may also influence decisions to immunize children younger than 12 when vaccines become available for that age group. Some experts have questioned whether the benefits to children outweigh the potential risks, given the low odds of serious illness in young children.

The C.D.C. strongly recommends Covid-19 vaccines for Americans ages 12 and older. The agency reported this month that the number of hospitalizations related to Covid-19 among adolescents in the United States was about three times higher than hospitalizations linked to influenza over three recent flu seasons.

As of June 10, nearly 17,000 children in 24 states had been hospitalized for Covid-19 and 330 children had died, according to data collected by the American Academy of Pediatrics.

The U.S. territory of Guam has begun offering Covid vaccinations to travelers from any country in a bid to lift tourism to the island.

On Tuesday, the authorities in Guam announced that a program called Air V&V, which previously allowed U.S. citizens to visit and get vaccinated, would now be open to international tourists age 12 and over.

The program aims mostly at countries in the Asia-Pacific region, where the rollout of vaccines has been relatively slow. The first three tourists will arrive from Taiwan on Wednesday evening, according to the Guam-based Pacific Daily News. Early next month, three more flights from Taiwan are set to bring about 500 passengers, another local news outlet, the Guam Daily Post, reported.

Carl Gutierrez, president of the island’s visitor bureau, said in a statement, “This program captures a unique demographic of travelers around the world that are tired of waiting to get vaccinated in this pandemic.”

Visitors will need to book a package from a participating government-approved hotel, which includes accommodation, meals, transportation to and from the airport, coronavirus tests, health monitoring and two doses of a vaccine. Participants can choose from the vaccines made by Pfizer and Moderna, which require two doses, or the “one and done” shots from Johnson & Johnson.

The travelers are required to present a negative coronavirus test result before departing their home country and must quarantine for seven days upon arrival in Guam. They will receive a first vaccine shot on their second day on the island.

But it is not a cheap vacation for visitors who opt for a vaccine that requires two doses and who remain on the island for three weeks to get both: Hotel rooms are about $150 to $350 a night, while the additional coronavirus measures cost a flat rate of $880 per person.

About 71 percent of Guam’s population of 169,000 has had at least one vaccine dose, while 63 percent are fully inoculated.

Nearly 80 percent of American high school juniors and seniors say the coronavirus pandemic has affected their plans after graduation, and 72 percent of 13- to 19-year-olds have struggled with their mental health, a new survey shows.

The survey, conducted by America’s Promise Alliance, a nonprofit group, found that 58 percent of teenagers reported learning entirely or mostly online in the 2020-21 school year, and 22 percent said that they had learned about half online and half in person. Nineteen percent said they had learned mostly through in-person instruction.

The results are from a nationally representative survey of 2,400 high school students conducted in March and April.

Among those who said the pandemic had affected their plans after high school, one-third said they would attend college closer to home; one-quarter said they would attend a two-year college instead of a four-year institution; 17 percent said they would attend college remotely rather than in person; and 16 percent said they would put off attending college. Seven percent said they were no longer planning to attend college.

Nearly half the respondents who changed their plans said they were doing so because of financial pressure, suggesting that the pandemic will probably widen educational inequalities among young adults.

Given the extraordinary swell of racial-justice activism over the past year, the survey also asked students about how their schools had handled race issues. Two-thirds reported that “the history of racism” had been taught at their schools. But Asian, Black, Latino and multiracial students were less likely than white students to say that the curriculum represented their own “racial and ethnic background.”

Organizers of the Tokyo Olympics said on Wednesday that they would ban alcohol at the Games, bowing to an outcry from a Japanese public that is deeply skeptical of hosting the event and weary of months of pandemic restrictions.

Two days earlier, the organizing committee said that it was considering sales of alcohol during the Games, which are scheduled to begin in Tokyo on July 23. That prompted outrage from many Japanese, with Tokyo and several other areas just emerging from a prolonged state of emergency during which restaurants were prohibited from selling alcohol as a virus control measure.

On Wednesday, the president of Tokyo 2020, Seiko Hashimoto, said that the committee had consulted with experts and decided to ban the sale and consumption of alcohol at Olympic venues “to prevent expansion of infection.”

Asahi Breweries, an official partner and one of the largest beer and spirits producers in Japan, endorsed the ban. “We totally understand the decision by the committee,” said Takayuki Tanaka, a company spokesman. “We will keep supporting the Games’ success.”

The alcohol ban is the latest sign that the Tokyo Games, postponed from 2020 because of the pandemic, will be unlike any other. This week, organizers said that crowds would be limited to 50 percent of a venue’s capacity, up to 10,000 people. Only spectators who live in Japan will be permitted to attend, with the organizers having decided back in March not to allow fans to travel to the Games from overseas.

Organizers are still determining what the crowd guidelines will be for some outdoor events such as marathons and whether viewing events that could attract large groups should be allowed in certain parts of the country.

After a sharp spike in May, coronavirus cases in Japan are receding, with daily totals of new cases nationwide having fallen by 38 percent over the past two weeks. A sluggish vaccination drive is starting to pick up pace, but with only 8 percent of the country fully vaccinated, according to New York Times data, the Olympic events are set to take place in front of crowds that are mostly not immunized.

Global Roundup

When Chancellor Angela Merkel of Germany received her second coronavirus vaccination recently, she was given a Moderna shot to follow the AstraZeneca one she received in mid-April, a spokesman confirmed on Tuesday.

Germany has permitted “mix and match” vaccinations for those who received one AstraZeneca dose before the authorities introduced age-specific recommendations at the end of March. Since then, the combination of an AstraZeneca shot followed by either the Pfizer-BioNTech or Moderna vaccine has become standard in Germany for those under 60.

It was not clear why Ms. Merkel, who will turn 67 next month, chose the mixed approach.

Initial studies suggest the combination of the two types of vaccines is effective, but a report published in May in The Lancet, a medical journal, also found that side effects were more common.

AstraZeneca shots make up only about 17 percent of the doses administered in Germany, while Moderna vaccines account for just 9 percent. The Pfizer-BioNTech vaccine is the most used, with nearly 71 percent of doses so far (unsurprising, perhaps, as BioNTech is a German company). A relatively small number of Johnson & Johnson vaccines have also been administered.

Unlike other world leaders, Ms. Merkel refrained from widely publicizing her vaccinations with a selfie photograph or public event. After her first dose in April, her spokesman merely tweeted a picture of her W.H.O.-issued vaccination booklet. It is not even clear when exactly Ms. Merkel received the second dose, but a spokesman confirmed on Tuesday that it had been in the last couple of days.

Currently, 52 percent of the German population has received at least one dose of a vaccine. Ms. Merkel joins the 32 percent of Germans that are fully vaccinated.

In other news from around the world.

• The government of New Zealand announced on Wednesday that it would impose social-distancing and mask-wearing requirements until Sunday in the city of Wellington, after a tourist visiting the capital from Sydney, Australia, over the weekend tested positive for the coronavirus. New Zealand on Tuesday began a 72-hour pause on quarantine-free travel from the Australian state of New South Wales, which includes Sydney, after more than 20 cases were reported in the eastern suburbs of the city.

• The Red Cross has urged residents of the South Pacific island nation of Fiji to get vaccinated after a surge in new coronavirus infections there reached record highs. The health and humanitarian organization said that new infections were doubling every 10 days as the country grappled with the more transmissible Delta variant, adding that “misinformation and rumors” on social media were stoking fear and undermining immunization efforts.

CASTLE DONINGTON, England — At 5 p.m. on Friday, a metal band called Death Blooms walked onstage in a field in Derbyshire, England, and launched into a pummeling track to open Download Festival, Britain’s first large-scale music festival to take place since the pandemic began.

A second later, several hundred rain-soaked fans — including two men dressed as bananas — began careering into one another in front of the stage at Donington Park, arms and legs flailing, smiling ecstatically as they formed the first legal mosh pit in the country in 15 months.

Since the 1970s, music festivals have been a key part of the British summer: events where teenagers get a first taste of parent-free vacations, music fans find community and people generally get very muddy and carefree. But there is widespread concern that few events will go ahead this year despite nearly half of Britain’s population having been fully vaccinated against Covid-19. And organizers say they risk going bankrupt.

Several major festivals were canceled for the second year in a row after Prime Minister Boris Johnson said last week that social-distancing measures would continue in England until at least July 19.

Download, too, was initially canceled in March. Last weekend’s hastily arranged special edition was able to go ahead only because it was part of a government trial to see whether and how cultural life could return safely. Previous pilot events — two 3,000-person club nights and a 5,000-capacity rock concert in Liverpool — led to eight cases of potential coronavirus transmission, according to one of the scientists involved, Iain Buchan.

Download 2021 had a significantly reduced capacity of only 10,000 fans, and the lineup featured only British acts to avoid the risks of international travel and quarantines.

Attendees had to take a coronavirus test before going in, and agree to another one five days after the festival. But once inside in the grounds, masks weren’t required — though head banging, moshing and drunken conversations at the campsite were prevalent.

On Sunday, the last of 39 mass vaccination centers operated by the U.S. government closed in Newark, the end of an effort that administered millions of Covid-19 shots over five months in 27 states. Many state-run sites are also closed or soon will be.

The United States’ shift away from high-volume vaccination centers is an acknowledgment of the harder road ahead. Health officials are pivoting to the “ground game”: a highly targeted push, akin to a get-out-the-vote effort, to persuade the reluctant to get their shots.

President Biden will travel to Raleigh, N.C., on Thursday to spotlight this time-consuming work. It will not be easy — as Dr. Anthony S. Fauci, the president’s coronavirus response coordinator, discovered last weekend, when he went door-knocking in Anacostia, a majority-Black neighborhood in Washington, with Mayor Muriel E. Bowser.

In an interview on Tuesday, Dr. Fauci said he and the mayor spent 90 minutes talking to people on their front porches. He said he persuaded six to 10 people to get their shots, though he did encounter some flat refusals.

“We would say, ‘OK, come on, listen: Get out, walk down the street, a couple of blocks away. We have incentives, a $51 gift certificate, you can put yourself in a raffle, you could win a year’s supplies of groceries, you could win a Jeep,’” Dr. Fauci said. “And several of them said, ‘OK, I’m on my way and I’ll go.’”