U.S. regulators opened up COVID-19 intensified injections to all adults on Friday, expanding the government’s campaign to strengthen protection and early prevent coronavirus cases that may worsen with the holidays.

After at least 10 states have begun to provide boosters to all adults, Pfizer and Moderna announced the Food and Drug Administration’s decision. The latest action simplifies what has been confusing so far by allowing anyone 18 years or older to choose any company’s booster six months after the last vaccination—regardless of which vaccine they received first. Qualified list.

But there is one more step: The Centers for Disease Control and Prevention must agree to extend Pfizer and Moderna’s boosters to healthy young people. Its scientific adviser is scheduled to have a debate later on Friday.

If the CDC agrees, then tens of millions of Americans will receive three doses of protection before the new year. Anyone who has received a dose of Johnson & Johnson vaccine can get a booster.

All three COVID-19 vaccines used in the United States still provide strong protection against serious diseases (including hospitalization and death), but protection against infection may weaken over time. Previously, the government has eliminated the boosters of Pfizer and BioNTech vaccines, as well as similar Moderna vaccines, which are only applicable to vulnerable groups, including the elderly in the United States and people with chronic health problems.

As new COVID-19 cases have steadily increased in the past two weeks, especially in states where cold weather has forced people to stay indoors, the scope of operations has been expanded.

Because of these worrying trends, some states did not wait for federal officials to take action. Utah and Massachusetts are the latest states to announce the opening of boosters to all adults last week.

Everyone’s booster is the original goal of the Biden administration. But in September, based on the continued effectiveness of the vaccine in most age groups, the FDA advisory panel voted against the idea by an overwhelming majority. Instead, they only approved additional Pfizer doses for the most vulnerable.

Since then, government officials, including Dr. Anthony Fauci, have continued to support wider use of boosters, noting that even mild infections in young people can lead to “long-term COVID” and other complications.

Fauci said at a briefing on Wednesday: “I don’t know of any other vaccines. We are only worried about keeping people away from the hospital.”

Last week, Pfizer and its German partner BioNTech submitted new data to prove that a wider range of boosters can help control infections during a critical period.

BioNTech CEO Ugur Sahin told reporters during a visit to Washington last week: “Under the current circumstances, we have absolutely no chance to control the pandemic without providing a booster for everyone.”

The two companies studied 10,000 adults of all ages and found that even in the presence of a surge in delta variants with extra infectiousness, enhancers can restore protection against symptomatic infections to approximately 95%. It is too early to know whether this high level of protection after the third shot will last longer than after the second shot. Shaheen said the company will carefully track this.

Supporting this evidence is that real-world data released by the UK this week show that once boosters are provided to middle-aged and elderly people, protection will see the same increase. Israel attributed its extensive booster to helping to fight off another wave of viruses in the country.

More than 195 million Americans are fully vaccinated, defined as having received two doses of Pfizer or Moderna vaccine or a single dose of Johnson & Johnson vaccine. More than 30 million people have already received boosters.

Before the expansion, people who were vaccinated by Pfizer or Moderna were eligible for the third dose if they were older or were at high risk of COVID-19 due to health problems or work or living conditions. Since a single J&J injection is not as effective as its two-dose competitors, any J&J recipient can receive the booster at least two months later.

But people who do not meet the criteria often get an extra shot because many vaccine sites do not check eligibility.

The U.S. Food and Drug Administration previously ruled that people receiving booster doses can receive a different brand of vaccine from the vaccine they initially received.

Some experts worry that all the attention to boosters may undermine efforts to reach the 60 million Americans who are eligible but have not yet been vaccinated. There is growing concern that rich countries are providing a wide range of boosters when poor countries cannot vaccinate a small part of their population.

Dr. David Dowdy of the Bloomberg School of Public Health at Johns Hopkins University said: “In terms of the number one priority in reducing transmission in the country and around the world, this is still getting people to get the first vaccine series.”