Some Surprising Aspects of the Swine Flu (H1N1)

With the onslaught of news articles regarding the ongoing swine flu pandemic I am sure that each and every person in the United States is aware of the risk of contracting the disease.  However I am not sure that everyone is aware of a few of the particulars regarding the 2009 H1N1 virus, cross strain immunity and the 2009/2010 flu season.  The Centers for Disease Control and Prevention compiles data for each flu season in an effort to determine the efficacy of past immunization campaigns and to determine the severity of and level of response appropriate to epidemics and pandemics as they arise.  The 2009 H1N1 pandemic has a few factors which make it somewhat of an anomaly among other influenza strains.  Without going into the biology behind these factors, this article will serve to disseminate some information that may or may not set the minds of many parents at ease.

A quick examination of the pediatric death data for the 2009/2010 flu season (available here) reveals that the actual number of pediatric deaths as of week 41 (53) is less than half the number of pediatric deaths (116) during the entire 2008/2009 flu season.  However it is important to remember that all of the data for the 2009/2010 flu season is not yet available as the season is far from over.  The other important issue revealed by these data is that the 2009/2010 flu season had a secondary peak of pediatric deaths during the summer weeks.  This is not normally seen with the seasonal flu as children are not in school and therefore transmission of the disease from child to child is less likely.  It is possible that because this is a new strain of the flu virus in humans its severity in children is associated with lack of previous inoculation with other strains either by vaccination or by contracting any strain of the flu virus.  This alone may account for the apparent increased severity of the virus in the pediatric population versus the severity of the seasonal flu.

Arguably past inoculation via actual disease contraction versus vaccination may result in better cross strain immunity as your immune system recognizes and responds to all foreign antigens whereas vaccines are often monovalent meaning that they are designed to illicit immunity to a single aspect of the virus (a.k.a. an antigen).  In theory, if there is a protein found on all influenza virion and your immune system responds to that antigen then a single inoculation could result in immunity to all strains of the virus.  Evidently this is not the case as most people that do not receive vaccinations and thus develop polyvalent immunity are still apt to contract the disease more than once during a lifetime.  The severity of the 2009 H1N1 virus in the pediatric population is most likely a result of many factors including but not limited to no cross-strain immunity in that population and physiologic factors in children making their immune response different than in the adult population. 

Vaccine manufacturers often produce monovalent vaccines due to the fact that such vaccines may produce a stronger and faster immune response versus polyvalent vaccines.  Despite this, polyvalent vaccines could be more effective against future outbreaks of similar strains.  This is not an advocacy communication for polyvalent vaccines but rather an attempt to make the average individual understand that regarding any virus with multiple strains, actual disease contraction and recovery may result in a greater long term benefit versus inoculation with a monovalent vaccine.  Considering the potential physiologic factors associated with the 2009 H1N1 virus and the pediatric population, monovalent immunization is warranted based strictly on the immunity benefit.  As for the potential for vaccine side effects, no statement can be made at this time due to limited data.

published 2 years ago

Jamie

175 points