Flu vaccine this year may be less effective than previous years

This year's flu vaccine is likely to be less effective than last year's according to the CDC (Vox). The problem is that the most common strain of influenza virus (which causes flu) circulating this winter, H3N2, has mutated so much that the vaccine may not protect against it. Typically the flu vaccine offers between 60-90% protection (probably closer to 60%). This year the vaccine may reduce the risk of flu infection by less than 50%.

Of course you should still get your flu shot because 50% protection is better than no protection at all. It is important to remember that 5-20% of the population contract flu each year, and in the U.S. approximately 25,000 people die from flu-related causes each year. It is especially important for pregnant women to get a flu shot (CDC):

"Flu is more likely to cause severe illness in pregnant women than in women who are not pregnant. Changes in the immune system, heart and lungs during pregnancy make pregnant women more prone to developing severe illness from flu, which can lead to hospitalization or even death. A pregnant woman sick with the flu also has a greater chance that her unborn baby will suffer serious problems, including premature labor and delivery."

Indeed, a new study from England reports that "[n]early one in ten pregnant deaths caused by flu. [...] Despite this, around 60% of pregnant women in England have yet to get the flu vaccine this winter."

If you do catch the flu, there are antiviral drugs like Tamiflu but their effectiveness is controversial, although their efficacy is optimized when given within two days of starting symptoms. Of course it is simpler to avoid getting flu in the first place, and the key part of that strategy is getting the flu shot.

Finally, it is important to dispel the myth that the flu vaccine can produce flu-like symptoms or even the flu itself. As I have described previously: "The virus particles in the flu vaccine have been thoroughly killed, and so the shot cannot give you flu. Some vaccines will use an attenuated virus (i.e. greatly weakened) but the most common flu vaccine uses dead virus." Thus, the most typical side-effect from a flu shot is a sore arm (from the injection itself).

In summary, although it will probably be less effective than previous years, You Should Still Get Your Flu Vaccine Shot.

Figure 1. This year's flu shot will offer less protection than in the past but it will still offer significant protection against the flu.