Fall will soon be here and it’s time to start thinking about the flu. Most people us the term “flu” in a very generic sense, meaning anything from cold symptoms to having a case of vomiting and diarrhea. The “flu” in this column refers to respiratory influenza.
Records since 2010 indicate the number of deaths from influenza has ranged from 12,000 to 79,000 per year. Note that these deaths were over a 12-month period whereas COVID-19 has killed over 180,000 Americans in just six months. Hospitalizations for influenza vary between 140,000 and 960,000 annually.
Influenza is caused by influenza viruses, with Type A and Type B causing the majority of infections. Type B typically does not cause severe disease, whereas Type A can be lethal, particularly in the young, elderly, and those who have compromised immune systems. Influenza viruses are completely different than coronaviruses, one of which causes COVID-19.
Type A influenza virus can be broken down further into different subtypes or “serotypes” based on which proteins are found on the surface of the virus. When you read about influenza virus with a name like “H3N2,” the “H” and “N” refer to two different proteins on the surface and the numbers refer to the serotype. The serotypes are also often given common names usually from their geographic origin such as Influenza A “Hong Kong.”
Influenza viruses are constantly changing or mutating slightly so that each flu season presents new serotypes. Virologists make an educated guess each year on what serotypes of virus might occur the following year and formulate that year’s vaccine accordingly.
It appears that the predominant serotypes of influenza A this year will be H3N2 and H1N1. H3N2 tends to cause more severe disease. This year’s vaccine will cover these two serotypes as well as one or two strains of Influenza B.
Individual vaccination still remains the best defense we have against developing full-blown influenza. It’s also important to attain a high level of vaccination in a community to reduce the spread of the disease to those who are more likely to die from complications of influenza.
It will be especially important this year to get vaccinated for influenza. We usually recommend vaccination in late September/early October, especially for elderly patients. If we have simultaneous outbreaks of influenza and COVID-19, it could rapidly overwhelm our ability to care for the sickest patients in our hospitals.
It’s important to note that receiving influenza vaccine each fall can’t give you influenza. The vaccine is made up of killed virus particles that can’t cause an infection. Some people do have some fever and aches after receiving the vaccine, but it’s a reaction to the vaccine, not an infection. Often people are exposed to cold viruses around the time they receive the vaccine. They come down with cold symptoms, and blame the vaccine for “giving them the flu.”
People with egg allergy can still receive the vaccine if they don’t have severe allergic (anaphylactic) reactions to eggs. Those who do have serious egg allergy should receive the vaccine in a doctor’s office or other facility equipped to treat severe reactions. There is a vaccine this season that is not produced using eggs.
I also occasionally hear another concern from patients that receiving influenza vaccine will “weaken” their immune systems and they won’t be able to fight the wild virus when they are exposed to it. Quite the opposite is true – by receiving the vaccine, you are exposing your immune system to the killed virus and your body will be prepared to react quickly to the virus if and when you are exposed to it. It takes your body a few days to produce antibodies to fight off the infection if you aren’t vaccinated. This leads to prolonged illness as well as an increased susceptibility to other illnesses like pneumonia.
Since a virus causes influenza, antibiotics are useless. There are anti-viral medications available to shorten the course of influenza, but they must be started in the first 48 hours of illness to be of any benefit. Many people choose not to take the medication since it is expensive, has some side effects and may only shorten the course by a day or two. These medications are not effective against coronaviruses.
If you contract influenza, the best thing to do is stay home, drink plenty of fluids and get as much rest as possible. Over-the-counter cold medications offer some relief and pain relievers can also be helpful if you do not have an allergy or other medical problems that limit your ability to take them. It is always important to wash your hands frequently to avoid catching the flu or spreading it to others. Hand washing with soap and water is more effective than using alcohol-based hand sanitizers.
Another benefit of social distancing and wearing masks to prevent COVID-19 is that doing so will likely reduce the spread of influenza.