Written By Ashima Seth
The trip to the physician for a seasonal flu shot is an annual event for most Americans. It usually takes place sometime mid-fall when we are most vulnerable to contracting the flu virus due to increased viability of the virus strains in conditions of low temperature and humidity . Although the flu may appear to be a tame disease due to a quick recovery period, the flu has been known to cause hospitalizations (140,000 to 710,000 in 2010) and even deaths (12,000 to 56,000 in 2010) . Influenza vaccinations are crucial as they prevent the spread of disease through the community.
A flu vaccine typically contains either dead or weakened virus strains against the strain that it is to protect against. About two weeks after receiving the flu shot, the body begins to respond by producing antibodies that fight off the weakened virus. In the interim during which the flu shot is effective (usually seasonal), the body’s immune system remains capable of recognizing the same strains of virus that it was injected with, and produces antibodies against it, thus protecting against influenza infections.
Flu vaccinations typically come in two types: trivalent vaccines protect against one type B, and two type A strains, while quadrivalent vaccines protect against two type B strains and two type A strains (type A infects both animals and humans, whereas type B only affects humans ). Although, trivalent vaccines are used as traditional flu shots, quadrivalent vaccines are growing in circulation due to the additional defense they provide against type B influenza, and may, in the future, replace trivalent vaccines completely .
The flu season this year has been particularly severe, with the H3N2 Influenza strain A being a leading cause of hospitalizations . One of the primary reasons for this is that the current flu shot only offers a substantive defense against the H1N1 strain of influenza A, and not the H3N2. Another factor that has contributed to the severity of this epidemic is a recent mutation in the influenza A H3N2 strain that makes it harder to battle, leading to the flu shot being only 30% effective against the currently circulating virus strains . There is also evidence of the decline of the effects of flu shots over the years .
The mutations taking place in the virus strains may be caused, in part, by the manufacturing process. Vaccinations for influenza in the U.S. are made primarily in chicken eggs which allow for greater production and lower cost. However, within a few hours of producing the virus in the eggs, it mutates. Producing vaccines in cells, would mean a greater cost to both the manufacturers and the public . With the current infrastructure being what it is, the current flu vaccination is our best shot at avoiding the sniffles this season.
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