As director of the Global Health and Emerging Pathogens Institute at Mount Sinai Hospital, Dr. Adolfo García-Sastre conducts research on the influenza virus, including ways to produce better vaccines and antivirals. He has been working on influenza for 25 years.
Who's at risk
For most Americans, influenza, or flu, is an inevitable yearly visitor. "Influenza is a respiratory disease caused by the influenza virus," says García-Sastre. "It's like a very bad cold, characterized by four or five days of high fever and prostration."
For 10,000 to 50,000 Americans every year, mostly elderly, the symptoms can worsen and lead to death, usually from flu-induced pneumonia.
The groups at highest risk of severe flu are the old and very young, people over age 65 or under age 2.
"The older you are, the higher the risk," says García-Sastre. "One exception was last year's pandemic H1N1, which left most people over 65 unaffected and was more severe in young people." Other factors that put you at elevated risk of severe flu are obesity, pregnancy, immuno-suppression and respiratory problems like asthma.
Flu spreads in three major ways, all of them respiratory.
"Phomites are surfaces that become contaminated," says García-Sastre. "Then someone touches the surface, gets the virus on the hand, and puts the hand in their nose or their eyes." Shaking hands with someone is a common example of this form.
The other main way flu spreads is through respiratory droplets, which can either be big or small. "Coughing and sneezing often cause big respiratory droplets that cannot fly more than 3 feet because they are heavy and quickly fall to the floor," says García-Sastre. "That's why the recommendation is to stay 3 feet away from people who are sick."
But coughing and sneezing also generate aerosol droplets, which are small particles that stay in the air and travel long distances. Doctors haven't determined which mode of transmission is most common.
Signs and symptoms
Most people are extremely familiar with warning signs of flu. "The symptoms are very typical of any febrile disease," says García-Sastre. "Most of them are respiratory symptoms: stuffy nose, sneezing, high fever, feeling very bad and prostration." Other symptoms can include headaches and GI symptoms. In severe cases, flu causes respiratory failure, which can lead to multiple organ dysfunction and death.
The common cold causes respiratory symptoms that can look like flu, but severity and timing can help you tell the difference. "Flu typically causes a fever," says García-Sastre. "In general, if you feel very bad and need to go to bed, it's usually flu, not a cold."
Flu also strikes seasonally, and the Centers for Disease Control tracks the number of cases so its researchers can report which states have a high incidence of flu.
"If you get a very bad cold during the peak of the influenza season, it's probably influenza," says García-Sastre.
The best treatment for flu is still prevention. "Vaccines work extremely well in healthy adults, but not as well in the elderly," says García-Sastre. "However, the best way to prevent elderly people from getting infected is to decrease infections among the younger people. Kids are the main spreaders of flu."
There are two types of vaccine: an inactivated vaccine, taken as a shot, and flu-mist vaccine, an alive but weakened virus that is taken intranasally.
"The injection is an inactivated vaccine, which cannot make you sick because the virus isn't alive," says García-Sastre. "It's also given intramuscularly so it can't reach the respiratory tract."
Vaccination takes three to four weeks to induce an immune response.
"One problem with the vaccine is that because the virus changes, the vaccine needs to change every year," says García-Sastre. "When a new strain comes, it's very difficult to create a new vaccine in time."
Once you've been infected with influenza, antivirals can prevent the virus from replicating.
"There are two classes of antivirals. Amantadine and rimantadine belong to the first class, two drugs that target the same viral protein and aren't currently recommended for many patients due to resistance of the circulating strains," says García-Sastre. "Neuraminidase inhibitors Tamiflu and Relenza are more effective against the current strains — Tamiflu is an oral product and Relenza is inhaled."
Taking antivirals can reduce death in cases of severe disease. "The problem with antivirals is that they need to be taken very early on to have impact," says García-Sastre. "Right now these drugs are effective, but in the future the virus may develop resistance to them."
The best hope for reducing the burden of influenza is research working to develop new vaccines and antivirals. "New research breakthroughs give hope on the possibility of a next generation of influenza vaccines that are called universal, which means they would protect against more different strains, even all different strains of the virus," says García-Sastre. "A second avenue of research is the development of new antivirals that target different components."
García-Sastre expects that doctors will be able to choose from many more anti-virals within the next five years.
Question for your doctor
If you think you have flu, talk to your doctor over the phone and ask, "Do you recommend Tamiflu?"
Tamiflu can also be used prophylactically.
"For instance, if one person has the disease in a family that lives together, taking Tamiflu can help prevent the rest of the family catching it," says García-Sastre.
What you can do
See a doctor if you have severe flu.
"If you start to feel really bad and have problems breathing, you might be getting severe influenza that could lead into pneumonia," says Dr. Adolfo García-Sastre. "And you might need to be hospitalized."
Watch out for complications.
The normal duration of flu is around one week. Longer bouts can be a sign something is wrong. For example, the flu could have given way to a bacterial infection, or it may not have been flu in the first place.
García-Sastre recommends everybody get vaccinated: "The more people get vaccinated, the less spreading there will be."
Take sensible precautions.
Frequently wash your hands, and don't cough or sneeze into your hands. The use of masks by people who have the disease can help, too.
Stay in bed.
"If you come to work, you are going to spread it," says García-Sastre.
The CDC runs a great website on influenza (cdc.gov/flu) with information on flu prevention, treatment and free resources.