Early flu season hits US with mutated H1N1 strain

Virus arrives two months early

This year, flu activity emerged on the west coast approximately two and a half months before usual. Dr Michael Osterholm of the University of Minnesota noted that this timeline has not been seen since the 2010 season. The Centers for Disease Control recorded 16,000 flu-related hospitalizations so far while expecting infections to rise in the coming weeks. Experts say travel patterns may have contributed but there is no completely ironclad explanation for why this occurred.

Mutated strain affects young adults

This leading strain is an H1N1 virus with the G155E mutation that shows characteristics similar to those found in strains from before 2009. According to Dr Amesh Adalja of the Johns Hopkins Center for Health Security, individuals aged under 25 including teens and young adults possess reduced immunity against this particular variant. Initial studies indicate the pathogen might evade certain immune defenses acquired through previous infections or immunizations. This season has recorded a single US pediatric death linked to influenza, affecting an elementary student not located in Denver.

Vaccine match is weaker than usual

This year the vaccine was developed before the mutation emerged meaning it is a weaker match against infection. Dr Alex L Greninger of the University of Washington states differences in response depend more on the individual infected than the virus itself. People with diminished cardio respiratory capacity face higher risks when heart disease pushes them over the edge during illness. The World Health Organization forecast was off because this particular variant emerged after experts chose what went into the vaccine.