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ATLANTA — The flu vaccine turned out to be a big disappointment again.

The vaccine didn’t work against a flu bug that popped up halfway through the past flu season, dragging down overall effectiveness to 29%, the Centers for Disease Control and Prevention reported Thursday.

The flu shot was working well early in the season with effectiveness put at 47% in February. But it was virtually worthless during a second wave driven by a tougher strain, at just 9%.


There was “no significant protection” against that strain, said the CDC’s Brendan Flannery.

Flu vaccines are made each year to protect against three or four different kinds of flu virus. The ingredients are based on predictions of what strains will make people sick the following winter.


This season’s shot turned out to be a mismatch against the bug that showed up late.

That pushed down the overall effectiveness to one of the lowest in recent years. Since 2011, the only season with a lower estimate was the winter of 2014-2015, when effectiveness was 19%. A mismatch was also blamed then.

Vaccines against some other infectious diseases are not considered successful unless they are at least 90% effective. But flu is particularly challenging, partly because the virus can so quickly change. Overall, flu vaccine has averaged around 40%.

Flu shots are recommended for virtually all Americans age 6 months or older. Officials say the vaccine is still worthwhile since it works against some strains, and it likely prevented 40,000 to 90,000 hospitalizations over the winter flu season.

The CDC bases vaccine effectiveness on preventing cases bad enough to send someone to the doctor.

— Mike Stobbe

    • Las personas que reciben regularmente una vacuna anual contra la gripe tienen menos probabilidades de infectarse con el virus. No exactamente inmune, pero menos probable. Ahora, en Bolivia hay un nuevo virus de catoro no vacunas. Y que vas a hacer

  • As an airline employee in constant contact with people, you’d think I’d get the flu every year, but I don’t. I get a flu shot, and over the last ten or so years, I think I got it twice, and other than a head cold, last winter was fine too. Hedge your bets, get a shot.

    • I’m a Nurse and I haven’t received a flu shot for over 30 years and I haven’t gotten the flu in over 30 years. Immune diseases are on the rise in the USA. Flu Vaccines mess with your immune system. Go ahead get all the flu shots you want.

  • I have health issues and get sick easily,because of this I want to take every caution possible.The times I’ve had a flu shot I’ve gotten sick from the shot and still get sick later.Then I read this article and I’m confused and disappointed.Why wouldn’t we have a better vaccine

  • Researchers from Australia said that “killer T-cells”, found in more than half of the world’s population, showed their effectiveness in testing against all common types of influenza. In my T-cells significantly exceeded T-helper cells 1808 in the normal 450-850, T-cytotoxic 945 is normal 270-540, T-lymphocytes 2835 are normal 600-2500, lymphocytes 4108 are normal 800-3600 and leukocytes 7900 are normal 4500-8500. similar. Local immunologist noted lymphocytosis as a result of T-cell activity In an immunogram, the frequency of lymphocytes is 38%. And in scientific journals, the rate goes up to 40%. And I have 49 lymphocytes. This means lymphocytosis. but during a pandemic someone is unlikely to look at the price. I want to help in the fight against the flu. I am the most healthy sick person with two rare internal incurable diseases. For 4 years, only 1 time had the flu and. And had the flu for 3 days

  • I got it this year and I get the flu shot every year, this year I got hit in Marcha nd was this sicker then I had ever been in quite awhile

  • I hot the flu one year, and never felt sicker in my life. I somehow avoided a hospital stay, but I have been getting a flu shot every year since and have not gotten that sick again, while I watch my co-workers who don’t get flu shots end up taking 7-10 days off work and sounding miserable.

  • It is funny. All winter, there were non stop coverage stories in every form of media, saying how much better this years flu shot was than the previous years disappointing vaccine. Turns out, it was actually a worse match. It is almost as if the media is unreasonably biased in favour of the flu shot industry…….

    • Flu vaccine formulations are made by estimating the next year’s circulating strains, it takes thousands of doctors and scientists almost a whole year to make a brand new vaccine every year. However the formulation is always our best estimate. Early in the year the vaccine was well matched to circulating strains, however a second, unpredicted wave of a new strain hit…we can’t just make a new vaccine and deploy it Midway through a season….it’s not media bias, it’s science.

    • +1 for reading comprehension. “The flu shot was working well early in the season with effectiveness put at 47% in February.” It WAS working well. Then the conspiracy theory “media is unreasonably biased in favour of the flu shot industry”… damn internet just making Idiocracy more possible by the minute.

  • The only year I got a flu shot (6 years ago) I got the worst flu in my life ever, only 2 months after the shot. I did some more reading up on how each year the content of the vaccine is totally based on just “educated guess work”. With the unacceptably low success rate (again reflected in this article), I have not had a flu shot ever again. It simply is not effective enough. The best solution to not get the flu is stepped up “herd” hygiene – or avoidance.

  • What a shame this is. I’ll be opting out a gain next year. You know, we really need to start with some common sense solutions. For example, if you have the flu or a bad cold and plan on getting on a airplane take a mask! Or, ask the flight crew for a mask, they routinely carry them!

  • I am wondering should i cry or laugh ? i am not at all surprise with this current information or news from the . C.D.C as i wrote them more than two months ago , asking the questions as to why the reports for the year of 2018 Flu season deaths have not been released as at that time and the amount of funds spent by the Federal Government on health care in the year of 2018 , , they at the C.D.C could only tell me at that time that they are not sure about any of the questions that i requested from them . Most significant i still have not been provided with any updated information from the C.D .C . seperate from this report now published by you STAT as of today . Thursday . June , 27, 2019 at 4.21 .p.m daylight savings time . New York City . We are done . The health care system in this nation is gone . thanks .Trevor Merchant

    • The strain-content of the Flu vaccine has always been a crap shoot, or an educated guess based on reports from Australia’s and others’ winter season, and samples from migrating waterfowl. H3s are very difficult because they are capable of mutating in chicken eggs during vaccine preparation.
      I think money well spent would be to also teach the public how to avoid contracting the Flu. TV and social media are the perfect vehicles. They could start by instructing watchers NOT to touch their face unless hands have just been washed, for example.

    • I was curious about the effectiveness of the flu vaccine, and after much research, I can’t seem to get an answer to this: Has the percentage of flu cases decreased over the U.S. population over the last 30yrs now that so many more people get the shot? You would think if it was effective it would, but an email response from CDC scientist to me was that they don’t have good enough records to determine this. Also, they lump together deaths from “influenza and pneumonia” in there stats for “flu deaths”. I love science, but they need to stop lying to themselves that this is good science. I do think there will soon be a successful vaccine, but they’re not there yet. Maybe the “actual vaccine scientist” can find it.

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