By Richard Feldman

We have been fortunate the past few years to have mild influenza seasons, but the 2018 influenza season is a more severe one. Influenza is not just a bad cold. It can be deadly, not just for the old and frail but also for the young and healthy.

Each year, influenza severity and mortality varies with the virulence of the virus and how well the vaccine “matches” the circulating viruses. Nationally, yearly deaths can vary from less than 10,000 to more than 50,000. Flu viruses love to mutate during the season, and if they change and become dissimilar to the vaccine’s influenza components, the vaccine becomes less effective.

This season is a double whammy: The predominate H3N2 virus is a more virulent strain, coupled with the fact the virus appears to have mutated.

If you are very young or very old, the risks for influenza complications are the greatest, and the risk of death is the greatest for those 65 and older due to waning immune systems and the presence of chronic diseases. Also, there is ample evidence that chronic underlying conditions (either known or unknown to the patient) are additionally prone to exacerbation by influenza infection. The best evidence is for heart disease.

A recent study in the New England Journal of Medicine found that the risk of heart attack was six times greater while sick with influenza and dropped off dramatically thereafter. It is theorized that influenza creates body inflammation. This creates chemical stressors and inflammation in the coronary vessels promoting aggregation of platelets, rupture of atherosclerotic plaques, spasm and hypercoagulability leading to clotting off of the coronary arteries. Almost 70 percent of adults in the study who had a heart attack did not receive a flu shot.

Other previous studies also indicate a similar relationship between influenza and heart attack. A study in the Canadian Medical Association Journal revealed a 19 percent reduction in first myocardial infarctions for those 40 and older immunized against influenza within the prior year.

The Centers for Disease Control and Prevention report that seasonal influenza may lead to death from a variety of chronic underlying diseases. These deaths are frequently attributed to the chronic conditions rather than to the actual precipitating event – recent influenza infection. The list of chronic underlying diseases affected is extensive.

One of the best studies was a 2007 study appearing in the journal Vaccine involving over 100,000 mostly healthy people 65 and older. The study subjects were either vaccinated or unvaccinated against influenza and followed for 10 months. For those immunized, there was a 22 to 65 percent reduction in mortality for various conditions including stroke, heart disease, diabetes, renal disease, pneumonia, COPD, malignancy, and also all-cause mortality. The most impressive reductions were stroke at 65 percent, renal failure at 60 percent and diabetes at 55 percent.

Everyone six months and older, healthy or chronically ill, should receive a yearly vaccine. Even when the vaccine has a low efficacy, there are benefits including less severe illness and reduced risk for hospitalization and death.

Richard Feldman, M.D., is an Indianapolis family physician and the former Indiana State Health commissioner. Send comments to