Each year, influenza, or the “flu” causes widespread illness, hospitalizations, and even death. But in the 2017-18 flu season, the entire continental US was shown by the Centers for Disease Control to have widespread flu activity this winter. It is the first time since the CDC started monitoring flu activity in this way 13 years ago. Why is the flu so bad this year?
The strain of flu that people catch varies from year to year, and there is a typical “flu season” every year. It varies depending on the area but is generally the six cold months of the year, depending on your hemisphere. When the flu arrives in a populated area, it can be tracked by how many positive samples are reported to the CDC, and of course by reported hospitalizations. The incidence of flu has been found to generally take 3 weeks to peak in an area and another 3 weeks before it diminishes.
This flu strain is worse
This year’s most prevalent flu strain is in the H3 family of viruses, specifically Influenza A-H3N2. In general, cases of H3 flu tend to be more serious and longer-lasting than other strains, especially among the older population and with young children. The flu season of 2014-2015 was also dominated by an H3 strain of flu that was one of the worst on record.
What about the flu vaccine?
Because different flu strains circulate from year to year, the flu vaccine is changed to combat the strains scientists predict will be dominant. Sometimes they are unable to include all of the necessary inactivated viruses in the vaccine (so that the antibodies your immune system makes are not a match for the flu virus you’re exposed to).
The other factor that plays a role in how effective the flu vaccine proves to be is the way that the vaccine is developed. Most vaccines are grown in chicken eggs. That is why people with egg allergies are advised against getting the typical flu vaccine. Scientists correctly predicted this H3N2 flu virus and included it in the vaccine, but the virus mutated in the eggs in a way that made it mostly incompatible with the human flu virus. It turns out that avian flu varieties are better combated by vaccines grown in eggs. The result is that this year’s flu vaccine is only about 30% effective against flu in the US. However, 30% is still significant when you consider how the flu affects the population. People who are vaccinated may also have reduced severity of symptoms and be sick for less time than those who aren’t.
Timing of this year’s flu season
The flu gained traction earlier than usual in the US this year. It was more widespread than usual in November 2017, right before all the travel and get togethers the holidays bring. It is likely that more people were exposed to the flu over the holiday season than usual, contributing to the severity of this flu season.
If you suspect you have the flu, visit your doctor right away. Anti-viral medications are most effective when taken 48 hours after becoming infected. You can rest assured that SC Internal Medicine Associates & Rehabilitation provides comprehensive care for adults and will help you avoid or kick the flu this season, and every season. Call (803) 749-1111 for an appointment at our office in Irmo, South Carolina today.
