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What's the estimated effectiveness of this season's flu vaccine so far? (Photo: Getty)

How is 45? Well, that depends on what you are talking about, of course. Eating 45 doughnuts in one sitting is probably not so good. Batting .450 in a Major League Baseball season? Thats good. All-time best good. A flu vaccine thats 45% effective? Thats certainly not the all-time best. But its still better than it was measured to be this time last year: 29%.

The 45% number came from a report released yesterday by the Centers for Disease Control and Prevention (CDC). This report indicated that so far the flu vaccine has been an estimated 45% effective in preventing influenza-associated medically attended acute respiratory illness. Ummm, what the who attending a cute illness what? This may seem like a jumble of words if you dont speak medical-ese.

Lets break it down a bit. Influenza-associated means the result of the flu. Medically attended says that you sought medical care for the problem. Acute respiratory illness stands for a disease affecting your respiratory tract that is new and not something that has been going on for a while already.

Thus, the flu vaccine is estimated to have been 45% effective at preventing flu-associated respiratory illnesses that resulted in doctors visits. Not 45% effective in preventing the flu in general. Not flu in which you melt into your bed and dont go anywhere for several days. But flu that gets you to go to the doctors office. The number was even higher for those 6 months to 17 years of age. Kids and adolescents had 55% for this type of vaccine effectiveness.

So, back to the original question: how is 45? In general, when the influenza virus strains in the vaccine match the strains that are circulating the population, such effectiveness tends to be between 40% and 60%. Of course, in years that the strains dont match, vaccine effectiveness can be lower. So 45% is kind of like sushi in a food court. Not the best that it could be. But it does its job.

Where did the CDC get these vaccine effectiveness numbers? Well they came from the U.S. Influenza Vaccine Effectiveness Network, which conducted studies from October 23, 2019 to January 25, 2020. During that time period, five study locations in Michigan, Pennsylvania, Texas, Washington, and Wisconsin enrolled 4,112 patients, all 6 months of age and older, who had visited clinics for acute respiratory illness accompanied by cough when the flu virus was known to already be circulating in the area.

The researchers asked each patient whether he or she had received the flu vaccine at least 14 days earlier this season and tested their noses or mouths for presence of the flu virus. Ultimately, 1,060 (26%) of the study participants ended up testing positive for the influenza virus. The percentage of participants in each site who had received the flu vaccine ranged from 38% to 61%.

From the results, they calculated an odds ratio. Not an odd ratio as in a weird ratio but an odds ratio calculated as such: the odds that a person who tested positive for the flu also had been vaccinated earlier in the season divided by the odds that a person who tested negative for the flu had been vaccinated. The following formula then calculated the estimated vaccine effectiveness: 100% x (1- odds ratio).

Counting the number of clinic visits underestimates the number of people who get the flu in a season ... [+] as many people suffer without seeking medical care. (Photo: Getty)

So this is a somewhat indirect method of evaluating the effectiveness of the flu vaccine. It is also from a specific sample of 4,112 patients. If you think political polls dont really represent what people think, you can imagine that numbers from a sample of people from particular locations may not really represent what is occurring throughout the country. Plus, numbers for particular parts of the flu season may not end up holding throughout the entire flu season. This flu season is far from over, and vaccine effectiveness can change over time as different strains become more or less prominent.

Oh, and remember this is vaccine effectiveness in preventing influenza-associated medically attended acute respiratory illness. Not the flu in general.

Moreover, dont go around saying, Im 45. Im 45. That may not be your specific number. The flu vaccine probably offers different levels of protection to different people. Remember, you are a snowflake and so is your immune system. This isnt a statement about your toughness. This is just a reminder that no two people and no two immune systems are identical. A vaccine basically presents inactivated or weakened versions of the viruses to your immune system and says, hey watch out for these. Its up to your immune system to respond. Therefore, the protection that you get depends on how your immune system reacts.

Regardless of your specific number, as they say with the flu, sword fighting, and sex (not that the three are related), some protection is better than no protection. Nothing else even comes close to the vaccine in protecting against the flu. Taking supplements is not going to do it. Neither is a special diet, getting chiropractic treatments, douching your nose, or drinking whiskey. The CDC has estimated that the flu has already caused 12 to 17 million medical visits, 250,000 to 440,000 hospitalizations, and 14,000 to 36,000 deaths this season as of February 8, 2020. Those are not inconsequential numbers, and they will continue to grow. They are still much, much, much higher than what the new coronavirus (2019-nCoV) has caused in this country as I have explained previously for Forbes. If you havent yet gotten the flu vaccine, it is still worth getting.

Here is the original post:
This Years Flu Vaccine: CDC Says How Effective It Is - Forbes

This entry was posted on February 21, 2020 at 10:48 am and is filed under Immune System. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |