Flu Vaccine Helps Prevent Dangerous Pneumonias

Doctor giving a flu shot

If you’ve been to the doctor recently, you’ve probably already been asked if you’d like to get your flu shot. While millions of Americans opt for the protection of the vaccine every year, some have questioned the effectiveness of the flu vaccine in preventing certain serious illnesses. A study published in the Journal of the American Medical Association has bolstered the already well-established proof of the effectiveness of the vaccine by looking at the effects of the flu shot on several thousand people hospitalized with pneumonia. Their findings show the importance of getting a yearly flu shot.

What do we know about effectiveness of the flu vaccine?

There are two aspects to understanding the effectiveness of the flu vaccine. On a virus level, how well the flu vaccine works depends on whether or not the flu vaccine is a good match for the flu virus that season. Unfortunately, the virus changes its makeup every year, which prevents our body from building up permanent immunity to it. Since we can’t know exactly what the virus will look like each year, the top researchers in the field use their best estimate of what it will be to make a vaccine. How well that estimate matches the virus can change from year to year, which can change how effective the vaccine is at protecting you.

Beyond that year-to-year variation, researchers also try to look at the overall picture of whether the flu vaccine prevents dangerous illness. To do this, they study the health of various groups of people over the course of many years and look to see if getting a flu vaccine helps reduce disease and health complications related to flu infection regardless of yearly variations. Those studies have found that getting vaccinated helps keep kids, pregnant women, and older adults out of the hospital and intensive care unit.

How did the researchers test for flu shot effectiveness?

The researchers followed more than 5,000 patients from 2010 to 2012. About half had pneumonia and the other half did not. Within the pneumonia group, the researchers identified the cause of that pneumonia and classified people based on whether the flu caused or didn’t cause the pneumonia. They then also looked at whether the individuals were vaccinated with the flu shot or not. The team used statistical analysis to pull apart whether getting a flu shot during the period of time they studied made you less likely to end up with any pneumonia or with a pneumonia specifically related to the flu virus.

What did the researchers find?

The data showed that people hospitalized with a pneumonia caused by the flu were much less likely to have been vaccinated than those who didn’t have flu-related pneumonia. That indicates that people who are vaccinated are better protected from pneumonia than those who aren’t. The study was observational, meaning the team didn’t intervene to directly test the flu vaccine. They gathered data on what was happening in the hospital and tried to figure out what was causing patterns they saw. As a result, they can’t say with certainty that the flu shot led to the lower levels of flu-related pneumonia, but the study does show a strong link.

Interestingly, the study found that those with weakened immune systems didn’t see as much of a benefit from the vaccine as healthier individuals. They think this may have to do with the fact that the immune system in these people doesn’t respond as quickly to the shot, which lowers the protection. Studies are underway to see if higher doses of the flu vaccine might fix this issue.

What does this mean for me?

If you’re on the fence about getting the flu vaccine and have questions about its effectiveness, this study should help to calm those concerns. The flu vaccine has been tested time and again and has been shown to be safe and effective at preventing flu infection and the sometimes-deadly complications that can result. Talk to your doctor if you have questions about whether the flu vaccine is right for you. The vaccine should be available at your local pharmacy or doctor’s office and is most helpful at the beginning of the flu season.