The U.S. flu season is underway.

Cases of norovirus, a highly contagious stomach bug, are climbing in the Northeastern U.S. Nationwide, about 12% of most recent norovirus tests sent to the U.S. Centers for Disease Control and Prevention were positive.

Federal health officials say older U.S. adults who got a COVID-19 shot in the fall should get a booster dose now.

More U.S. hospitals are requiring masks and limiting visitors as health officials face a post-holiday spike in flu and other illnesses.

U.S. health officials say at least seven states are seeing high levels of the flu and that cases are rising in other parts of the country.

Flu is decreasing in many parts of the country after an alarmingly early and strong start to the season.

U.S. health officials say some people getting Pfizer or Moderna COVID-19 vaccines should consider waiting up to eight weeks between the first and second doses.

Average daily COVID-19 cases and hospitalizations are continuing to fall in the U.S., an indicator that the omicron variant’s hold is weakening across the country.

An early look at the performance of COVID-19 booster shots during the recent omicron wave in the U.S. showed a decline in effectiveness against severe cases, though the shots still offered strong protection.

If you test positive for COVID-19, you should isolate at home, stay away from others and tell the people you’ve been in close contact with.

The U.S. has seen a string of COVID-19 outbreaks tied to summer camps in recent weeks in places such as Texas, Illinois, Florida, Missouri and Kansas, offering what some fear could be a preview of the upcoming school year.

Pfizer says it is about to seek U.S. authorization for a third dose of its COVID-19 vaccine.

Can I take painkillers before or after a COVID-19 vaccine? The concern about painkillers is that they might curb the very immune system response that a vaccine aims to spur. AdThe U.S. Centers for Disease Control and Prevention recently updated its guidance to recommend against painkillers before a COVID-19 shot. Read more here:What should I know about COVID-19 vaccines if I’m pregnant? How do we know the COVID-19 vaccines are safe?

FILE - In this Oct. 28, 2020, file photo, a worker wearing gloves, and other PPE holds a tablet computer as he waits to check people at a King County coronavirus testing site in Auburn, Wash., south of Seattle. The latest surge in U.S. coronavirus cases appears to be larger and more widespread than the two previous ones, and it is all but certain to get worse. But experts say there are also reasons to think the nation is better able to deal with the virus this time around. Several states posted records Tuesday, including over 12,600 new cases in Illinois, 10,800 in Texas and 7,000 in Wisconsin. Governors made increasingly desperate pleas for people to take the fight against the virus more seriously.

NEW YORK – U.S. health officials Wednesday redefined what counts as close contact with someone with COVID-19 to include briefer but repeated encounters. For months, the Centers for Disease Control and Prevention said close contact meant spending a solid 15 minutes within 6 feet of someone who tested positive for coronavirus. On Wednesday, the CDC changed it to a total of 15 minutes or more — so shorter but repeated contacts that add up to 15 minutes over a 24-hour period now count. The CDC advises anyone who has been in close contact with a COVID-19 patient to quarantine for two weeks. At times, the prisoners wore masks, but there were encounters in cell doorways or in a recreational room where prisoners did not have them on, the report said.

It’s a strikingly different landscape from 2008, when Nashville last hosted a presidential debate between Democrat Barack Obama and Republican challenger John McCain at Belmont University. Fast-forward to a year of unprecedented disruption to live music and other public gatherings, and Tennessee health officials are now reporting record-breaking virus numbers in the days leading up to the debate. But Belmont University President Bob Fisher says canceling the debate never crossed his mind. He says he was always confident Belmont could pull off the debate, even in a pandemic. Approximately 150 people are expected in the debate hall, including up to 35 Belmont students working as ushers.

Facing public skepticism about rushed COVID-19 vaccines, U.S. health officials are planning extra scrutiny of the first people vaccinated when shots become available — an added safety layer experts call vital. The poll from The Associated Press-NORC Center for Public Affairs Research found only 46% of Americans want a COVID-19 vaccine and another 29% are unsure. Looking back at vaccines for other diseases, side effects show up within two to three months, said FDA vaccine chief Dr. Peter Marks. Then it would take FDA several weeks of breakneck work to decide if a COVID-19 vaccine really was suitable for emergency use, Marks said. And states including New York, Rhode Island and Virginia are forming advisory committees to review the safety of any COVID-19 vaccines that pass FDA.

NEW YORK – President Donald Trump said Thursday he doesn't think he's contagious anymore, but medical experts say that's impossible to know a week after his diagnosis with COVID-19. But there's no way to know for certain that someone is no longer contagious so soon after falling ill, experts say. Earlier in the day, Trump said he was still taking dexamethasone, a steroid that can reduce fevers. His doctors haven't held a press conference since Trump left the hospital, only releasing statements with limited information. They have not released any details about his test results, including when Trump last had a negative virus test before he got sick.

President Donald Trumps startling COVID-19 diagnosis serves as a cruel reminder of the pervasive spread of the coronavirus in the United States and shows how tenuous of a grip the nation has on the crisis, health experts said. (AP Photo/Jae C. Hong, File)President Donald Trump’s startling COVID-19 diagnosis serves as a cruel reminder of the pervasive spread of the coronavirus and shows how tenuous of a grip the nation has on the crisis, health experts said. Some of Trump's top advisers and allies also have tested positive recently. Some hospitals in Wisconsin have run low on space, and experts warned of a likely surge in infections during the colder months ahead. Colder weather is also on the way, which will likely increase the chances people will congregate together indoors,” Michaud said.

The torrid coronavirus summer across the Sun Belt is easing after two disastrous months that brought more than 35,000 deaths. (AP Photo/Wilfredo Lee, File)The torrid coronavirus summer across the Sun Belt is easing after two disastrous months that brought more than 35,000 deaths. Whether the outbreak will heat up again after Labor Day and the resumption of school and football remains to be seen. Now they worry that Labor Day will contribute to the virus's spread. If we were to see the same effect from Labor Day, we would be in worse shape than we were after July Fourth, said Williamson.

The first COVID-19 vaccine tested in the U.S. revved up people’s immune systems just the way scientists had hoped, researchers reported Tuesday -- as the shots are poised to begin key final testing. Fauci said final testing will include older adults, as well as people with chronic health conditions that make them more vulnerable to the virus — and Black and Latino populations likewise affected. Nearly two dozen possible COVID-19 vaccines are in various stages of testing around the world. Candidates from China and Britain’s Oxford University also are entering final testing stages. The 30,000-person study will mark the world’s largest study of a potential COVID-19 vaccine so far.

These are some of the tips in long-awaited guidance from U.S. health officials about how to reduce risk of coronavirus infection for Americans who are attempting some semblance of normal life. These guidelines are really directed toward ordinary Americans trying to make decisions about risk every day.But there are notable omissions. The CDC has put out many sets of guidelines, including some for churches, camps, schools and transit agencies. They also offers a list of questions people should consider before going out, and some things to think about in particular situations. ___The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institutes Department of Science Education.

(CNN) -- The World Health Organization tried on Tuesday to clear up confusing comments about how often people can spread the coronavirus when they do not have symptoms. On Monday, Van Kerkhove had said that what appear to be asymptomatic cases of Covid-19 often turn out to be cases of mild disease. Van Kerkhove added that she was referring to reports from WHO member states when she made her comments on Monday. "I thought they were getting very prissy and trying to slice the salami very fine," Schaffner said about WHO's comments on Monday on asymptomatic spread. The best scientific studies to date suggest that up to half of cases became infected from asymptomatic or pre-symptomatic people.

But that process, known as contact tracing, relies on people knowing who theyve been in contact with a daunting task if theyve been to a mass gathering. These events that are happening now are further threats to the trust we need, said Dr. Sandro Galea, dean of the Boston University School of Public Health. And those are the communities that have been hardest hit by the coronavirus in the U.S. and most in need of public health measures to help control it. That is not what contact tracing is, said Dr. Tom Frieden, former director of the federal Centers for Disease Control and Prevention. "Contact tracing is a service to patients and their contacts to provide services for patients and warning for contacts.

CNN – To stop the spread of coronavirus, health officials have instructed the public to practice social distancing -- staying home, avoiding crowds and refraining from touching one another. Practice as much social distancing as your work allows. "Social distancing does not mean social isolation. But before you do, call the daycare center or meet with staff to ensure they're implementing social distancing measures. How long will we have to keep social distancing?

The United States' top doctor has one simple request: Stop buying face masks. US Surgeon General Dr. Jerome Adams' message, posted to Twitter on Saturday, was a response to face mask shortages as people stocked up due to coronavirus concerns. "Seriously people," he began, and though it's a tweet, you can almost hear the exasperation in his plea. "STOP BUYING MASKS!" With coronavirus popping up in the United States, some have begun buying face masks as a form of protection, despite the likes of the US Centers for Disease Control and Prevention and Vice President Mike Pence saying they're unnecessary.