Flu strains can change by “shift” or “drift”. Shift is said to occur when gene segments reassort to create a new virus. This how pandemics start. Drift is said to occur when enough small changes accumulate so that the virus can evade the immune system. This can result in a bad flu season.
We are told that neither of these events have occurred. If so, how to explain the current very bad flu outbreaks?
From KIWA radio:
Dr. Gregory Poland is a vaccine expert at the Mayo Clinic in Rochester.
“What we’re seeing unfortunately is a strain called influenza-a h3n2 and that’s an important seasonal virus because it is the one that causes the most morbidity and mortality in humans.”
He says the last time we saw a widespread outbreak of this strain was about a decade ago and it was responsible for thousands of deaths.
There are a couple of problems with this statement:
1. The CDC says the strain causing massive outbreaks this year is the same strain that caused a mild flu season last year.
2. The H3N2 strain that was so severe in 2003-2004 was a clear example of drift.
Strange how these two facts are not being mentioned by flu experts.
From the CDC this week:
325 (99.4%) of the 327 H3N2 influenza viruses tested have been characterized as A/Victoria/361/2011-like, the influenza A (H3N2) component of the 2012-2013 Northern Hemisphere influenza vaccine.
2 (0.6%) of the 327 H3N2 viruses tested showed reduced titers with antiserum produced against A/Victoria/361/2011
From the CDC in 2004:
Of the 949 influenza A (H3N2) isolates that have been characterized, 106 (11.2%) were similar antigenically to the vaccine strain A/Panama/2007/99 (H3N2), and 843 (88.8%) were similar to the drift variant, A/Fujian/411/2002 (H3N2).