The flu season started earlier this year than the past two seasons, saw a rapid rise in cases in recent weeks and may already be near a peak.
But it is far from over. What's worse, the predominate virus strain circulating now is causing severe symptoms.
"Right now, you can walk into any emergency room shift and a good percentage of the patients will be there for flu-like symptoms," said Dr. David Pierce, a vice president at Kaleida Health, and chief medical officer at Millard Fillmore Suburban and DeGraff Memorial hospitals.
Most flu activity occurs between December and February, but it can last into May. That means there is still plenty of time to get a flu shot, health officials say.
Patient visits to local hospitals show that the flu appears to be peaking earlier than last year.
The facilities in the Catholic Health system, for instance, tested about 900 people with flu-like symptoms in the first 10 days of January. Last year, during the same period, they tested fewer than half that number. Roughly 21 percent of the tests are coming back positive for the flu, which is slightly lower than the current national average of 24.7 percent and close to the annual peak seen at the hospital system.
"We are seeing a dramatic rise in cases in the emergency room with the symptoms associated with flu, as well as a fair number of people being hospitalized," said Dr. Kevin Shiley, medical director of infection prevention and control.
Pierce said a similar trend is occurring in the Kaleida Health hospitals, where 272 cases have been diagnosed since mid-November.
Officials at the Centers for Disease Control and Prevention put it this way: Influenza is everywhere.
"There’s lots of flu in lots of places," Dr. Dan Jernigan, director of the CDC’s flu division, said last week in a media briefing.
The 22.7 hospitalizations per 100,000 people in the United States the week ending Jan. 6 is up from 13.7 the week before. As expected, the highest hospitalization rates are among individuals 65 and older and children 5 and younger.
But there are growing number of hospitalizations among those between ages 50 and 64, and reports of young, otherwise healthy, adults who have died from the flu, Jernigan said.
Flu season has hit as many hospitals must cope with a shortage of intravenous fluid bags caused after Hurricane Maria in September damaged a major manufacturing facility in Puerto Rico. Hospital officials here say they have monitored supplies closely, conserved when needed and worked with suppliers.
The vaccine is designed to protect against the three or four influenza viruses that research indicates are most likely to spread in a flu season. Because the flu virus can change its characteristics and the most-used vaccine takes months to produce, the vaccine is never 100 percent effective, and its effectiveness varies each year.
Studies indicate the vaccine generally reduces the risk of flu by 40 percent to 60 percent among the overall population. Last year, in the United States, overall effectiveness of the vaccine was 39 percent, meaning the vaccine reduced the risk of getting the flu by that much.
The CDC says this season’s flu vaccine includes the same H3N2 vaccine component as last season, and most circulating H3N2 viruses that have been tested in the U.S. this season are still similar to the H3N2 vaccine virus. Information so far suggests that vaccine effectiveness against the predominant H3N2 viruses will probably be somewhere around 30 percent.
"We don't know yet exactly what the effectiveness will be, but we do know that it will be greater than zero," said Dr. Gale R. Burstein, health commissioner in Erie County.
Her point: Even a small reduction in risk is valuable, especially for those at higher risk of complications, including older people, pregnant women, very young children and people with certain long-term medical conditions. As an example, public health officials estimate that in the 2015-2016 flu season, when only 2 of 5 people got vaccinated and overall effectiveness was 47 percent, the vaccine prevented 5 million flu illnesses, 2.5 million medical visits and 71,000 hospitalizations.
Doctors say they continue to confront two long-standing myths about the flu.
The first: That the vaccine causes influenza. That's not true. As Burstein said, "This is biologically impossible."
People often mistake colds and other respiratory illnesses for the flu. Also, it's possible to get the flu after immunization in the period before the vaccine takes effect. Flu vaccines given with a needle are grown in chicken eggs with inactivated virus, or made by methods that do not require using the virus.
The second: That antibiotics cure the flu.
Not so. Antibiotics are for bacterial infections. Flu is caused by a virus.
"We see this in the emergency room all the time. It's an inherent assumption by a lot of patients, although most people are reasonable if you educate them," said Pierce.
Health officials say the vaccine is the best way to prevent the flu. By getting immunized, people also reduce the risk of spreading the flu to others, especially those at high risk of such complications as pneumonia or death. It takes about two weeks for antibodies to develop in the body that protect against flu.
Here are five things to know about the flu this season:
What is the flu?
There are four types of influenza viruses, and the seasonal flu that makes us sick is caused by A and B.
The A viruses are divided into subtypes and strains. Health officials describe the current types of influenza A found in people as H1N1 and H3N2. Influenza B viruses are broken down into lineages and strains — for instance, B/Yamagata and B/Victoria.
So far this season, influenza A, H3N2, has been the most common form of influenza, accounting for more than 80 percent of the cases nationwide. This strain tends to cause the most severe flu, more hospitalizations, and more deaths. B influenza is around but peaks later in the season.
What's the difference between the flu and a cold?
Viruses cause both of these illnesses, but, generally, colds are less severe. Flu almost always causes fever, whereas a cold does not. Flu tends to make your entire body sick. A cold is usually concentrated in the head, nose and chest. The flu can cause serious complications and death.
Why does the flu get so much attention?
CDC estimates that flu, depending on the severity of the season, results in 140,000 to 710,000 hospitalizations a year. In recent years, CDC estimates that flu-related deaths ranged from a low of 12,000 in 2011-2012 to a high of 56,000 in 2012-2013.
There have been 20 reported deaths of children so far this season from the flu.
Why do we need to get a vaccination every year?
The influenza virus constantly changes its genetic makeup, so the vaccine must change every year to keep up with those changes. Because it takes months to produce the vaccine, public health officials around the world monitor the strains of the virus in circulation and then make an educated guess as to which ones will predominate each new flu season. Efforts are underway to develop a better vaccine.
What other steps can be taken to prevent or treat the flu?
The easiest is good personal hygiene — hand-washing, covering the mouth when coughing, staying home if sick.
Flu can also be treated with an antiviral medication, such as TamiFlu. The drugs, which must be started within two days of becoming sick, can lessen symptoms and shorten the course of the illness by a day or two, a potential difference-maker for people at high risk of complications, Burstein said.