Eighty thousand Americans died of the flu last season, according to preliminary data from the Centers for Disease Control and Prevention.
This is more than the number killed in traffic collisions, firearms violence or opioid overdoses.
It was also the deadliest flu season since 1976, when the agency began to publish annual influenza trends, said CDC director Dr. Robert Redfield of the Associated Press in late September.
Seasonal Influenza is a killer, even in milder years. Recently, mild flu season tends to kill about 12,000 Americans, and heavier flu seasons kill up to 56,000.
But 80,000 dead are an unusually big toll. Here's what has led to the massive spike ̵
Why the Flu Season Became So Bad Last Year
The flu is a viral respiratory disease that causes uncomfortable fever, headaches, cough, muscle aches, and runny nose that make many people unhappy in the fall and winter. There are four types of influenza viruses – A, B, C and D – and the seasonal flu is caused by influenza A and B. Every year different strains of these viruses circulate. Last year's flu season was more severe than usual because it included the dreaded H3N2, a strain of the influenza A virus that causes more health complications and is more difficult to prevent.
H3N2 hits can be fatal, especially in vulnerable groups such as the elderly and children. The researchers are still not sure why, but they have found that a flu season in which the H3 virus is dominant is generally more unpleasant – with more hospitalizations and flu-related deaths than seasons with mostly H1N1 or influenza B viruses. And last year most flu cases were about the H3N2 strain.
H3N2 is particularly difficult to prevent with the flu shot
Another reason for the severity of the flu season last year is that the H3N2 virus is hard to prevent the flu vaccine. To understand why, you need to understand how the flu vaccine works – and why it is by no means perfect.
The vaccine is designed to protect humans against three or four strains of A and B viruses that researchers believe to be most prevalent in a given year. For example, each year, health authorities essentially make assumptions about which strains and mutations are making the rounds. As you can imagine, this is not an easy task – and in reviewing influenza vaccine efficacy research, researchers have found that years of circulating H3N2 take years to make the vaccine less effective.
Edward Belongia, a senior epidemiologist at the Marshfield Clinic Research Institute in Wisconsin, who has studied the efficacy of influenza vaccines, found that the combined vaccine efficacy during H3N2 seasons was 33 percent. This means that the vaccine reduces the risk that a human being about a third must go to the doctor. The efficacy of influenza vaccine increased to 54 percent during the influenza type B season and to 67 percent in the H1N1 season.
So, as the researchers expected, studies on how well the flu vaccine worked in America last season suggested it was worse than in previous years.
Your kind reminder to get a flu shot
If you did not get the shot, get it. The flu season lasts until spring and there is enough time left to protect yourself and your family.
As I have already reported, flu vaccines have a very low risk – and the great potential benefit of avoiding serious illnesses. Therefore, Belongia argues that even some protection is better than no protection. "[It] still prevents many hospitalizations and deaths," he said.
Although the vaccine does not work well with H3N2, it provides better protection against other influenza viruses. And the AP reports that health authorities this year expect to see these milder strains better prevented by the vaccine.
Besides, vaccination is not just about protecting yourself; it's about protecting others with herd immunity. "Vaccinated people act essentially as barriers to outbreaks, because diseases can not penetrate them and infect others," said my colleague German Lopez. "When a sufficient percentage of the herd is immune, diseases can not be transmitted to enough people to thrive." Even if you think you can take an influenza virus, you could transfer it to weaker people who can not.
Older people, young children, pregnant women and anyone with weakened immune systems are particularly susceptible to influenza. Therefore, herd immunity and vaccine are particularly important for these groups. Last year, according to the CDC, 80 percent of child deaths occurred in unvaccinated children.
As far as the treatment of influenza is concerned, most people can simply wait at home for their illness, rest and be careful not to infect others. But people in these high-risk groups – young children, pregnant women, people over 65, people with other chronic illnesses – may want to seek immediate medical help and antivirals such as Tamiflu.
There are other, even simpler things that you can do to reduce the risk of getting the flu or transmitting the virus to others. These include good old-fashioned hand washing that covers your mouth when you cough and stay home when you're sick.