Federal health officials are trying to tell if this year's harsh flu season led to an increase in a rare but dangerous brain complication in children.

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.

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.

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. The CDC advises anyone who has been in close contact with a COVID-19 patient to quarantine for two weeks. In a statement, CDC officials said the case highlights again the importance of wearing masks to prevent transmission, and that the agency's guidance can change as new information comes in. The CDC also says close contact can include hugging and kissing, sharing eating or drinking utensils with someone infected, and providing home care to someone who is sick.

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.

– Routine vaccinations for children and adults are vital in preventing the spread of infectious diseases, but data is showing that during this pandemic, vaccinations have declined drastically. That’s why the National Foundation for Infectious Diseases has launched a campaign called “Keep Up The Rates” to encourage people to protect themselves against viruses like mumps, measles, pneumonia and the flu. Schaffner said anyone over the age of 6 months should be vaccinated against the flu every year. And when it comes to the spread of coronavirus, researchers with the Department of Agriculture in Kansas are suggesting that mosquitoes and other biting insects cannot spread COVID-19. Unlike Dengue, Malaria and Zika, the study, which has not been peer reviewed, found that the virus behind COVID-19 can’t replicate after being ingested by mosquitos.

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.

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.

Only about half of Americans say they would get a COVID-19 vaccine if the scientists working furiously to create one succeed, according to a poll conducted May 14-18 by The Associated Press-NORC Center for Public Affairs Research. The NIH is creating a master plan for testing the leading COVID-19 vaccine candidates in tens of thousands of people, to prove if they really work and also if they're safe. Among those who want a vaccine, the AP-NORC poll found protecting themselves, their family and the community are the top reasons. Yet the poll found just 25% of African Americans and 37% of Hispanics would get a vaccine compared to 56% of whites. Worldwide, about a dozen COVID-19 vaccine candidates are in early stages of testing or poised to begin.

Thirty states are seeing flu activity -- for this time of year, that's the most states in a decade. Only one season in the comparison had more activity at this time of year: the unusually severe 2009 pandemic flu season that broke records. "An early season could be a harbinger of a severe season, and we're all a little bit worried about that," said Schaffner, a longtime advisor to the CDC. There are several strains of flu, and the predominant one so far this season is an influenza B strain. "We are seeing more influenza B than we would expect this early in the season, and influenza B is particularly a problem for children.

CNN(CNN) - The aches, the sneezing, the sore throat, the exhaustion -- flu season is here, and you want to be prepared. Physicians say it's not too early to get a flu shot, and they are available at many pharmacies and doctor's offices around the country. Last year's flu seasonFor the 2018-2019 US flu season, which started October 1, 2018, and ended May 4, preliminary numbers from the CDC estimate there were nearly 42.9 million cases of flu, up to 647,000 hospitalizations and up to 61,200 flu deaths. The severity was moderate, the CDC reported, but it was record-breaker as the longest flu season in a decade. Looking at how bad a flu season was in Australia, which has winter when the United States has its summer, is not necessarily predictive of what the flu season will be like in the U.S., Jernigan said.

"It certainly is incredibly frustrating and upsetting to the public health community that we may lose measles elimination status, because we do have a safe and effective vaccine," Messonnier said. Losing measles elimination status would be a black eye to the United States, public health experts said. WHO removes a county's elimination status when measles has been spreading continuously for one year. CDC plans on releasing a detailed statement next week about the country's measles elimination status, according to Messonnier. Venezuela lost its measles elimination status in 2018, followed by Brazil earlier this year.

Public health experts sharply criticized CBP for what they called the agency's lack of transparency. The CBP official said his agency reports illnesses to state health departments. Public health transparencyIn the first seven months of 2019, more than 600,000 migrants were apprehended crossing the US southwest border. "We do share that information and record and coordinate through the established public health channels," he said. The Texas Department of State Health Services reports no pediatric flu deaths in that region of the state during the 2018-2019 flu season.