Striking Results in Mice
There are an increasing number of studies that point to long-term immunity offered by previous infection with H1N1 virus. This week, the National Institute of Allergies and Infectious Disease released the results of a study showing that the H1N1 vaccine worked to protect mice against contracting the 1918 strain of the influenza virus.
The study explained that strains of H1N1 can share similar features. The antibodies produced to fight the virus also take on similar characteristics and can help to protect a patient against different H1N1 strains.
The results of the study were quite striking. Within groups of mice, those injected with the H1N1 vaccine all survived exposure to the H1N1 strain that surfaced in 1918—causing mass devastation across the world. Of the mice that did not receive any vaccine or were injected with a vaccine for an entirely different influenza strain, all died after being exposed to the same 1918 virus.
Morbidity Rates Similar to Seasonal Influenza
Another study reported by the Centers for Infectious Disease Research and Policy (CIDRAP), suggests that exposure to seasonal influenza may have protected against H1N1 infection. The French study was published online last week by BMC Infectious Diseases.
The study found that rates of morbidity were similar to those for seasonal influenza, meaning that school-aged children were still more susceptible to contracting the flu. Mortality rates were higher in children and young adults, possible indicating that previous exposures to seasonal influenza or other previous strains of H1N1 influenza may have contributed to increased immunity in these groups. The CIDRAP article pointed out that this particular study may be problematic in its data collection and is not the first to point to a “shift in the mortality burden to younger people.”