CLOSE Researchers have developed a new way to predict the severity of the flu season "significantly earlier" than in the past. Buzz60 
 
 In this Sept. 16, 2014, file photo, a sign in a Walgreen store in Indianapolis tells customers about its flu shot services. (Photo: Darron Cummings, AP) 
 
 Flu season has arrived early to North America this year, and it may end up being a doozy. 
 
 Cases of flu tend to ramp up mid- to late-December and peak in January or February, according to Paul Sax, an infectious disease physician at Brigham and Women’s Hospital in Boston. But this year, things are different. 
 
 The Center for Disease Control and Prevention releases a weekly flu report where it tracks flu activity across the country. This year, the percentage of patients reporting flu-like symptoms reached the threshold of 2.2% by late November, an indication that flu season has started. 
 
 Not only has flu season arrived early, but the U.S. may be particularly hard-hit. It’s difficult to make predictions about how a flu season will play out, as flu viruses are wildly unpredictable. But the Southern Hemisphere experienced an especially bad season over the summer (their winter), with Australia reporting record-high numbers of influenza cases and a higher-than-average number of hospitalizations and deaths. 
 
 There are a several different strains of flu viruses, and the main culprit in Australia was a strain called H3N2. However, the flu vaccine was only 10% effective against that strain, meaning it reduced a person’s risk of infection by 10%, according to a paper published in the public health journal Eurosurveillance. 
 
 That same strain, H3N2, was the most common strain of virus in North America last season, and is likely to be this year as well. Experts worry because the H3N2 portion of the vaccine used here in the U.S. is identical to the one used in Australia. 
 
 While 10% seems low, “flu vaccines are usually only about 40% to 60% effective in the best of years,” said Martin Hirsch, an infectious disease physician at Massachusetts General Hospital in Boston and the editor-in-chief of the Journal of Infectious Diseases. 
 
 There are two major things that could contribute to this. 
 
 “It can be due to a change in what’s circulating in the human population, or a change in the vaccine that leads to a mismatch” between the virus and the vaccine, Hirsch said. 
 
 Circulating influenza strains may mutate after the World Health Organization decides what should go into that year’s vaccine. Or the vaccine itself may mutate while it is being grown — currently, vaccines are grown in eggs, but many experts don’t think that’s ideal as the vaccine virus tends to undergo mutations to adapt to growing in an egg. 
 
 But that doesn’t mean you shouldn’t go out and get your flu vaccine, Hirsch cautions. 
 
 “Even if the vaccine is only 10% effective against H3N2, the vaccine does protect against other strains that are circulating,” he said. “The most important thing is still to get your flu vaccine.” 
 
 Read or Share this story: https://usat.ly/2A9cMr3 ||||| NEW YORK -- Could this nasty flu season finally be winding down? U.S. health officials on Friday said fewer visits to the doctor last week were for fever, cough and other flu symptoms than during the previous two weeks. Flu-like illnesses accounted for 1 out of 16 doctor visits last week, while the number of states reporting high patient traffic for the flu also dropped, to 39 from 43. 
 
 Officials at the Centers for Disease Control and Prevention (CDC) said they're cautious about saying flu season has peaked but called the downturn encouraging. 
 
 "It does like the peak is behind us now," said Dr. Daniel Jernigan, director of the CDC's Influenza Division. Even so, he warned, "there is certainly a fair amount of influenza to go this season -- probably until mid-April." 
 
 Flu season usually peaks in February, but this season started early and surged for months. It has been driven by a formidable type of flu that tends to cause more hospitalizations and deaths. This year's flu vaccine is estimated to be only 25 percent effective against the H3N2 virus. 
 
 "H3N2 affects more older folks, with very high hospitalization and death rates," Jernigan said, while influenza B, which is now becoming more prevalent, tends to affect younger people. Overall, the flu vaccine has been more effective for children than adults this year, reducing illness by 59 percent among kids ages 6 months to 8 years old. 
 
 The CDC reports 13 more children died of the flu last week, bringing the number of pediatric flu deaths to 97 this season. 
 
 Even at this point in the season, health officials recommend people get a flu shot if they haven't already. 
 
 "There's still, potentially, eight weeks left of the flu season, and the CDC is saying, 'go and get the flu shot,'" CBS News' chief medical correspondent Dr. Jon LaPook said recently. "Overall, about a third of the people who got the flu vaccine were protected, but in kids under 9, almost two-thirds were protected against influenza." ||||| Joe Raedle / Getty Images file Russell Waddley of Miami received a flu shot in early December from Alina Pastoriza Garcia at a CVS pharmacy's MinuteClinic. Government health officials say new data show that the flu vaccine is about 62 percent effective at preventing illness this year. 
 
 Flu activity remains high across the United States, but there are signs this year's bad season may be waning in some areas, government health officials said Friday. 
 
 Forty-seven states reported widespread flu activity as of the week ending Jan. 5, up from 41 the previous week. Twenty-four states and New York City reported high levels of flu-like illness, but that was down from 29 states and NYC the week before, according to new data released by the Centers for Disease Control and Prevention. 
 
 Still, flu is unpredictable and illness could rebound or worsen, said CDC Director Dr. Tom Frieden. 
 
 "Really, only the next week or two will show whether we have, in fact, crossed the peak," Frieden told reporters in a conference call. "Nationally, it's likely that influenza will continue for several more weeks." 
 
 Flu activity was elevated all across the U.S., except in the far west region that includes Arizona, California, Guam, Hawaii and Nevada, the new report showed. 
 
 More than 3,700 people have been hospitalized for the flu since October, and 20 children have died, the CDC says. Most of the hospitalizations have been in people older than 65. For the first time this season, deaths associated with the flu rose into the epidemic category, though just barely, CDC officials said. 
 
 Vaccines given to fight this year's flu appear to be about 62 percent effective overall , according to data from some 1,155 children and adults with acute respiratory infections. Of people who got the flu, 32 percent were vaccinated. CDC officials characterize that level as "moderate" effectiveness and infection control experts say it's about what they expect from the shots. 
 
 "That's normal," said Dr. William Schaffner, chairman of the department of preventive medicine at Vanderbilt University in Nashville, Tenn. "It's a good but not a perfect vaccine." 
 
 This year's vaccines appear to be about 55 percent effective against influenza A strains, which are responsible for most illness and more severe cases, and about 70 percent effective against influenza B, which is usually less serious, the report showed. 
 
 That helps explain why some people who've received flu shots -- which are recommended for everyone older than six months -- say they've still gotten sick. It argues in favor of using antiviral drugs such as Tamiflu to help bolster vaccine effectiveness, or VE, CDC's report said. 
 
 "These early VE estimates underscore that some vaccinated persons will become infected with influenza; therefore, antiviral medications should be used as recommended for treatment in patients, regardless of vaccination status," the report concluded. 
 
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 / Updated By Maggie Fox 
 
 Flu activity increased “sharply” across the U.S. last week, and the virus is still widespread in all states except Hawaii, federal health officials said Friday. 
 
 At least four different strains of influenza are making people sick, the Centers for Disease Control and Prevention said. Flu vaccines are designed to protect against three or four of the strains but work poorly against the most common strain circulating, called H3N2. 
 
 Another 10 children were reported to have died from flu, the CDC said, although not all the deaths occurred last week. It can take weeks for states to gather the information and send it to CDC. So far this flu season, 30 children have died from influenza. 
 
 Last season, 110 children died from flu in the U.S. 
 
 Every year, influenza kills between 12,000 and 49,000 people and can send as many as 700,000 people to the hospital, the CDC says. It affects so many people that adult cases and deaths can only be estimated. 
 
 Related: Flu season's coming early, looking tough 
 
 The CDC says this is the worst flu season since the 2014-2015 season. Flu can vary a lot from year to year, and this year it’s spreading actively in all the states at the same time. In other years, it has usually moved in irregular waves, peaking in different parts of the country at different times. 
 
 “We’re seeing flu throughout the entire country,” said Dr. Nicole Alexander-Scott, director of the Rhode Island Department of Health and president-elect of the Association of State and Territorial Health Officials (ASTHO). 
 
 “By every measure – whether it’s by outpatient visits, hospitalizations, laboratory testing - this has been a very early season and a more severe one than recent influenza seasons,” agreed Dr. Karen Smith, director of the California Department of Public Health. 
 
 Related: How about a better flu vaccine? 
 
 Some hospitals are overwhelmed, said Dr. Larry Wolk, Colorado’s chief medical officer. 
 
 “We’ve had well over 2,000 influenza-associated hospitalizations. That’s double our average number of cases we usually see this time of year,” Wolk told reporters in a briefing organized by ASTHO. 
 
 Worried flu patients are flooding emergency rooms and Alexander-Scott said her state health department was trying to steer those who are not suffering emergencies away from emergency departments. Only the urgently sick or injured should be in the ER, she said – others should be calling their own primary care doctors or visiting urgent care clinics. 
 
 Related: Flu might be airborne 
 
 It’s still not too late to get a flu shot, all the officials said. Pharmacies and drug stores reported they still had plenty of supplies, and the CDC predicts flu season will last several more weeks at the least. 
 
 “It may be several months before this flu season ends,” Wolk said. ||||| share tweet pin email 
 
 This year’s flu season is off to a fast start and early indications suggest that it may be more severe than the previous season. 
 
 Four states currently have widespread flu activity, according to the Centers for Disease Control and Prevention. Last winter there were none at this time. 
 
 And it may be spreading fast. Dr. William Schaffner, who is involved in the CDC’s flu surveillance network in Tennessee, has noticed cases of influenza picking up "dramatically" in the last week. 
 
 Even worse, it appears the dominant strain will be H3N2, which can produce more severe illness, said Schaffner, an infectious disease specialist at the Vanderbilt University Medical Center. 
 
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 To get an idea of what a flu season in the U.S. will look like, scientists like Schaffner observe what happens in Australia, which experiences winter and the flu while Americans are having summer. In the summer of 2017, the flu was diagnosed in more Australians than the previous season — 168,337 versus 91,000 — with H3N2 predominant. 
 
 How effective is the 2017 flu vaccine? 
 
 Unfortunately, the flu vaccine in Australia, which is the same one available this fall and winter in the United States, was only 10 percent effective in preventing illness from H3N2. 
 
 “Typically in years when the predominant strain is H3N2, there are more hospitalizations, more severe disease and people tend to get sicker,” said Dr. Michael Ison, a professor of infectious disease and organ transplantation at Northwestern University’s Feinberg School of Medicine. 
 
 Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, suspects the vaccine won’t work any better in the U.S. 
 
 “It is possible that we will experience low vaccine effectiveness against influenza A (H3N2) viruses and a relatively severe influenza season if they predominate,” Fauci and colleagues wrote in an article published recently in the New England Journal of Medicine. 
 
 However, while vaccinated people can still get sick, generally they get a milder and less dangerous form of the illness. 
 
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 Also, the vaccine protects against other flu strains. 
 
 “The protection against the others is much higher — 50 to 70 percent,” Schaffner said. 
 
 Even if the flu vaccine is just 10 percent effect against H3N2, a flu shot is especially important for adults aged 50 and older. Because the influenza virus triggers an inflammatory response in the body, in the two to eight weeks after recovering, older adults have a three to five times increased risk of having a heart attack and a two to three times increased risk of having a stroke, said Schaffner. 
 
 H3N2 is known to cause a much more substantial inflammatory response than some of the other strains. 
 
 “We think of the influenza virus as attacking the throat, the bronchial tubes and the lungs,” he explained. “But it affects the whole body. It can involve the blood vessels, particularly those going to the heart and the brain. If they are inflamed they can clog up and that can produce a heart attack or a stroke.” 
 
 However imperfect the flu shots are, “current influenza vaccines remain a valuable public health tool, and it is always better to get vaccinated," Fauci and colleagues wrote in the Journal. 
 
 The CDC estimates that the flu shot prevented 40,000 deaths in the United States between the 2005-2006 and 2013-2014 seasons.
– Brace yourself: All signs point to a particularly bad flu season, reports the Upshot blog at the New York Times. For one thing, the CDC says the nation has reached the epidemic stage, and while that designation usually arrives every year, it's earlier than normal. The Verge notes that we didn't hit epidemic level until mid-January in the last two flu seasons. Also not helping: The number of people getting flu shots is lower than normal, and the vaccine itself is a worse match than usual for this year's strain. The mismatch means that the shot is about one-third less effective than normal, reports CBS News. “We’re already above the peak that we saw last year, and we’re increasing,” says a flu expert at the CDC, who predicts that this season's peak probably won't arrive for weeks. The agency says 22 states are now reporting high levels of the flu, up from 13 last week. Google Flu Trends reports much the same. One last piece of the puzzle: This year's most prevalent strain is H3N2, and H3 viruses in general tend to be the most dangerous, reports the Weather Channel.