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Posted by on Dec 31, 2009 in Epidemiology, Health care, Infectious diseases, Pediatrics, Pharma

Top 10 for ’09: No. 1

Top 10 for ’09: No. 1


No. 1: Pandemic H1N1

You were expecting something else?

Coming out of left field (ie, Mexico)* in April, the novel 2009 H1N1 (“swine flu”) virus caused an official global pandemic in June, according to the World Health Organization. Cases mounted rapidly, but fear of disease was mitigated by its relatively low mortality rate.** Drawing on their experience from the swine-flu epidemic of 1976, leading US neurologists first believed that a government-led vaccination campaign would be unlikely because of 1) low mortality and 2) the possibility of vaccine-associated Guillain-Barre syndrome (GBS). Boy, were they wrong.

In August, the CDC released its recommendations for the administration of developing H1N1 vaccines to 5 groups. The surprise: Instead of the historically targeted elderly, the CDC prioritized vaccination for children, young adults, and pregnant women because of their emerging risks of disease-related complications and death. Consequently vaccination was recommended for an estimated 159 million Americans as soon as vaccines became available, sometime in mid-October.

In May, the DHHS had contracted with 5 companiesCSL Biotherapies, GSK, MedImmune, Novartis, and sanofi-pasteurto produce either injectable or nasally administered vaccines for pandemic H1N1 to the tune of $932 million. Government orders for another $883,977,920 and $438,143,025 were placed in July and September, respectively. The total amounted to about 9 bucks per vaccine, which was being produced by the traditional method of viral incubation in fertilized chicken eggs.

This tried-and-true method ultimately led to a delay in vaccine production for 2 primary reasons: the fastidious nature of the 2009 H1N1 virus (when compared with seasonal influenza viruses) and limited chicken eggs. Turns out the pandemic virus required 2 eggs to create a single vaccine dose, instead of the usual one. By October, the federally contracted companies had only cranked out about 10% of the promised 120 million vaccine doses for US residents. Time was a-wastin’.

In October, the CDC investigators estimated that about 3 million citizens had already experienced symptomatic pandemic flu between April and July, on the basis of a probabilistic model. Confirming previous assessments, the incidence of disease and disease-related hospitalizations were considerably higher in children and young adults. Pandemic flu, overall, had necessitated about 14,000 hospitalizations and had caused about 800 deaths in the United States.

The following month, the CDC estimated that up to 34 million Americans had been infected between April and mid-October. Respective hospitalizations and deaths now ranged from 63,000 to 153,000 and from 2500 to 6000. Another age breakdown revealed that disproportionate numbers of younger adults (and to a lesser extent, children) remained susceptible to pandemic flu generally and severe disease specifically. About 45% of Americans who had died from pandemic flu had been healthy.

And then disease began to waneEarlier this month, only 25 states reported widespread activity. At the same time, data showed that the pandemic flu vaccines (the supplies of which were up) remained effective and were comparably safe. Specifically the risk of GBS appeared no higher than the typical background rate.

The latest recommendations: More than 30 “major health care provider organizations,” including the American Medical Association, the American Academy of Pediatrics, and the American Red Cross, are encouraging all US residents to receive a pandemic flu vaccine in anticipation of another wave of infection. An “open letter” to the American people states,

The H1N1 flu vaccine is safe, effective, and the best way to protect yourself and your family from the H1N1 flu. Over 110 million doses…are now available, with more coming every day. Now is the time to protect yourself and those around you by getting vaccinated against the H1N1 flu.

Links to selected Pathophilia posts on pandemic flu (and a few on seasonal flu) are provided here in chronological order.

* Instead of the historically expected East Asia.

** Estimated in the United States at 0.007%-0.032%.

Depiction of H1N1 virus from Wikipedia.

bmartin (1130 Posts)

A native East Tennessean, Barbara Martin is a formerly practicing, board-certified neurologist who received her BS (psychology, summa cum laude) and MD from Duke University before completing her postgraduate training (internship, residency, fellowship) at the Hospital of the University of Pennsylvania in Philadelphia. She has worked in academia, private practice, medical publishing, drug market research, and continuing medical education (CME). For the last 3 years, she has worked in a freelance capacity as a medical writer, analyst, and consultant. Follow Dr. Barbara Martin on and Twitter.

1 Comment

  1. Well, this was also the #1 health story in my life this year, as I got this the middle of December and am just getting better now (3 weeks later).
    Good stuff.