Guest Contributor, John Bogen, MD, provides another update on the H1N1 pandemic along with his observations with what to expect in the coming year.
Since August 30, 2009, 99+% of subtyped influenza A have been novel 2009 pandemic strains (944 different strains have been identified). And so far, seasonal H1N1 and H3N2 strains have not been resurgent, and have killed very few compared to past years. If the oft-quoted 36,000 deaths annually from seasonal influenza is correct (of which 90% are elderly), then we can be thankful this season that influenza has “only” killed about 10,000 due to it’s low virulence compared to seasonal H1N1 and H3N2, and the fact that elderly have some immunity to the pandemic strain due to their birth before the 1957 pandemic when H2N2 replaced H1N1 as the dominant strain.
The CDC website has posted weekly updates (usually on Fridays). The presentation has been quite clear.
What could have been done better? One could blame the foreign manufacturers for the delay in vaccine, which admittedly has made the vaccine have little impact on the pandemic this season, but I cut them some slack – the virus was identified in California in April, and the pandemic was not declared until June.
If you want to improve the system, you could make the case to reduce legal liability and red tape in the U.S. to encourage more vaccine manufacture in the U.S. (only the nasal version was made here this season), and encourage pharmaceutical companies to move past the slow chicken egg processes.
The one thing I disagree with the official govt policy now is the strong push for healthy individuals to get vaccinated, and consume the vaccine that has already been manufactured and paid for. Herd immunity [Note: herd immunity occurs when a sufficient percentage of the population either has had the influenza, or has been vaccinated against it that there is no longer anyone left to contract the virus-DW] is now very high due to the fact so many people contracted pandemic H1N1 already, with a smaller herd immunity effect due to the delayed vaccine. Healthy people have an extremely low mortality rate from pandemic H1N1 (most deaths were those with chronic illnesses as per usual, with a shift in absolute numbers towards younger people simply due to the fact that younger folk got so many more cases due to no innate immunity). In my humble opinion, it is now a waste of time to vaccinate healthy individuals, and time should be spent by us PCPs on our non-vaccine duties.
I offer a prediction that the pandemic is over (i.e. no more peaks this season) in the U.S., and we will not see a resurgence until the usual influenza season next winter. I also would not be surprised if pandemic H1N1 becomes the new dominant seasonal strain in subsequent flu seasons (as happened historically after the 1957 and 1968 pandemics).
I predict the vaccine next season will be quadrivalent, containing pandemic H1N1 strains in circulation now (i.e. an update from current vaccine that contains hemagglutinin from strains present last spring / early summer), the former seasonal H1N1 and H3N2 (just in case they don’t disappear from circulation), and influenza B. I do not have info on the seasonal vaccine being prepared for the southern hemisphere’s upcoming flu season (during our summer).
This whole exercise was a “rehearsal” for the event that we ever get a really devastating influenza A pandemic, as would occur if H5N1 (a.k.a. bird/avian flu with it’s 60% mortality) ever co-infected an animal or human with a highly contagious influenza A virus (e.g. any H1N1 or H3N2), genetic material was exchanged, and a new virus was born. The WHO and CDC will be even better prepared for future pandemics.
One more thing, we did not know the case-fatality rate or epidemiology of pandemic H1N1 when vaccine planning was performed in spring / early summer 2009. It is better to be over-prepared than under-prepared.
It is true HIV, TB, and malaria are devastating in other parts of the world, but that is a separate debate. The issue here is did public policy officials have the appropriate response in the U.S. to the influenza pandemic (I think yes), and what have we learned to plan better for next winter’s flu season.
And to end on a light note: