For example, when the Centers for Disease Control and Prevention announced new freedoms for the fully vaccinated populations, questions about traveling to see grandchildren were immediately asked.

The answer, said the CDC director, Dr. Rochelle Walensky was, as long as the vaccinated grandparents lived nearby. But the agency continues to warn Americans against travel in general.

“We know that after mass travel, after vacation, after vacation, there is an increase in some cases,” said Dr. Walensky on Monday night on MSNBC. “And so we really want to make sure that we – again with only 10 percent of the vaccinated people – limit travel.”

To the frustration of airlines and others in the travel industry, the latest guidelines come as students and families consider spring break plans almost a year after much of the United States first closed, and a growing proportion of Americans tentatively book trips later in the year.

Given the presence of virus variants in nearly every state and the need for further research into whether fully vaccinated people can still transmit the virus and other questions about the vaccines, Dr. Walensky that unnecessary travel should be avoided, at least for the time being.

“It’s just a first step,” White House press secretary Jen Psaki said Tuesday, referring to the agency’s new guidelines for fully vaccinated people. “As more people get vaccinated, they will look for ways to ease additional restrictions.”

The Biden government said Tuesday it is sending 15.8 million additional doses of vaccine to states, tribes and territories, and another 2.7 million initial doses to pharmacies, Ms. Psaki said. Currently, an average of 2.17 million vaccine shots are given each day, she said.

What is safe for newly vaccinated Americans and their unvaccinated neighbors and family members has been largely uncertain as scientists do not yet understand whether and how often vaccinated people can still transmit the virus. If possible, masking and other precautions are still needed in certain environments to contain the virus, the researchers said.

“We know the travel corridor is a place where people mix a lot,” said Dr. Walensky during a White House briefing on Monday. “We hope our next guidelines will have more science on what vaccinated people can do, maybe travel among them.”

Airlines for America, an industry organization, has argued that aircraft have very little risk of virus transmission due to high quality cabin ventilation systems, strict disinfection practices, and strict rules that require passengers to wear masks. The industry has also argued that it has an important economic role to play and that further travel restrictions could hamper recovery.

“We remain confident that this multi-layered approach will significantly reduce the risk and we are encouraged that science continues to confirm that the risk of virus transmission on board aircraft is very low,” the group said.

The first stimulus plan, which went into effect almost a year ago, included $ 50 billion in grants and loans to shore up the pandemic-ravaged aviation industry. In December, Congress approved an additional $ 15 billion in grants to employ airline workers. The aid bill passed by the Senate on Saturday includes an additional $ 14 billion for airlines, a move welcomed by the industry.

In a Monday letter to President Biden’s coronavirus response coordinator Jeffrey D. Zients, a coalition of travel and tourism trade groups asked to work with the White House on federal guidelines for temporary “health records” for viruses that are safe and could be used consistently Check test results or vaccination status. Such guidelines could also bring benefits beyond aviation, they argued.

“It could lead to wider adoption of procedures for reviewing test and vaccination records, from sports arenas to restaurants to business meetings, theme parks and much more,” the group wrote.

Currently, the Biden government requires people traveling to the United States from another country to submit a negative virus test. At some point this year, administrative officials pondered a similar requirement for domestic travel, a measure the aviation industry has opposed, saying it was unnecessarily restrictive and would harm an already ailing sector. The CDC said in February it is not recommending testing for domestic travel “at this point”.