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What's up with Failing Flu Vaccines?

by Andrew Zale 

The statistics are staggering: only halfway through the flu season, and flu-related deaths in San Diego County surpassed the previous seasonal record. Throughout the country, six percent of all outpatient hospital visits are flu-related, according to the CDC. In the eyes of many, the flu vaccine this year has simply failed. However, closer examination of the methodology scientists employ to create the annual flu vaccine reveals that this year may not be as much of an outlier as people believe.

What is the flu?

    Before understanding how scientists “guess” the flu strain every year, it is important to understand what the flu entails. The flu is a virus, which is essentially pieces of genetic material, DNA or RNA, wrapped in proteins. These proteins protect the genetic material and allow it to be inserted into other organisms. Once inside another cell, the virus hijacks the host’s cellular machinery to replicate its genetic material and proteins, which leads to proliferation.

    The flu virus can vary in a number of ways, most notably by the proteins that encapsulate the DNA. There are 29 different versions of two encapsulating proteins, referred to as H and N, with nearly 200 possible combinations of the two proteins. In addition to these two variables, differing antigenic types (A, B and C), different host origins (swine, chicken, etc.) and other factors relating to the location and time in which the virus was isolated, there quickly grows to be thousands of different possible combinations for a flu virus.  

    The CDC lists that the flu can cause symptoms such as a fever, cough, aches, fatigue, vomiting and diarrhea. "Flu is serious. Flu is unpredictable,” Dr. Thomas Frieden, former director of the CDC, once told National Public Radio.

How is the flu vaccine developed?

    When a virus enters a human body, our immune system recognizes it as foreign. Vaccines operate by preparing the body to fight certain foreign antigens. The fundamental idea behind vaccines is that by exposing the body to a weakened version of a virus, the immune system will be able to recognize and fight off the weaker virus, thus preparing the body for a subsequent real and unplanned infection.  

    What differentiates the flu virus from other viral infections is the need to be aggressive in developing new vaccines. The flu virus’ genetic material is error-prone, which means that when the DNA or RNA is replicated there is a higher chance of a mistake, which often leads to a mutation in the virus. This mutation may change the proteins that coat the genetic material and make the virus no longer recognizable by the immune response set up by a vaccine. In addition, since there are an innumerable amount of different flu virus strains due to mutagenesis over time, scientists must predict which type of flu virus will be the most prominent in a given flu season.

Why doesn’t the flu vaccine always work?

    The flu vaccine is an imperfect science: the resultant product is a culmination of large-scale data analysis that allows scientists to create a mix of the most probable three to four flu strains annually. However, from data analysis, to vaccine production and testing, to reaching the market, the flu  is ever-changing. The virus can mutate rapidly and certain strains can become more or less prominent, which weakens the efficacy of the vaccine.

    Jennifer Radtke, infection prevention manager of the University of Tennessee, told USA today, “It's just one of those years where the CDC is seeing that this strain of flu is only somewhat covered by the vaccine that was given this year…they're seeing that it's anywhere from 10% to 33% effective, so any time there’s a mismatch between the vaccine and the circulating strain of the flu, you’re going to see more cases.”

    Professor Mike Turner, the head of Infection and Immunobiology at the Wellcome Trust, wrote in the BBC, “Predicting which of these strains will become dominant in any given season is always a challenge. If, like this year, the main flu viruses are sufficiently different to previous years and the strains in the flu jab, more people may be infected. Flu viruses constantly evolve as they pass from person to person, changing their appearance so our immune system doesn't recognize them as easily.”

    These critiques are not to say that the flu vaccine is a broken science by any means. Currently, our best methodology is an imperfect one with variable results. According to the New York Times, over the last ten years, the percentage of outpatient flu-related hospital visits have ranged from as low as two percent and up to eight percent, during the 2009 swine flu outbreak. Even though the Swine Flu catastrophically affected nearly the entire world, it paled in comparison to the Spanish Flu of 1918-19, which killed nearly 50 million people. With no vaccines or medications to fight viral infections, the flu of the past was a devastating epidemic.  

    Turner went on to comment about this year’s vaccine saying, “A big problem is that the virus keeps evolving before the vaccine is ready. If the virus changes more than expected, or a minor strain becomes unexpectedly common, the vaccine will be less effective. While this year's vaccine is not as effective as hoped, it is still the best first defense available.”

What lies in the future of the flu vaccine?

    Scientists have been working toward a one-size-fits-all flu vaccine for at least a decade. In a news article published in Science in April 2006, scientists wrote about the efforts to create a universal flu vaccine based on invariant proteins, M2 and NP, that are members of nearly all flu strains. Dr. Gary Nabel of the National Institute of Allergy and Infectious Diseases reported in the article that, “having all of those efforts moving forward gives us more weapons in the arsenal and makes us more likely to find the best platform.”

    Although progress seemed to have stalled on the development of a broader flu vaccine, on January 18 of this year, UCLA scientists offered newfound hope. They reported in Science of a flu vaccine that contains a flu strain which is mutated to predispose the immune system to increase its communication upon infection. By priming the communication network of the immune system for a response, immune attacks against pathogens should be both quicker and stronger.

    Until such a vaccine becomes available, it is apparent that everyone will still be susceptible to the flu. The only remaining option is to get the annual flu vaccine, and, if you get sick, enjoy a bowl of homemade chicken noodle soup.