On March 17, the Massachusetts Department of Public Health, confirmed the state’s fourth pediatric death from influenza. “This has been a very difficult flu season for the residents of Massachusetts,†Dr. Alfred DeMaria, DPH’s director of communicable disease control, indicated. The number of flu cases which have been severe enough to be tested at hospitals and doctors’ offices was more than three times the number for last season as of March 13, Donna Rheaume, a spokesperson for the department, tells Infection Protection.Â
According to the state, “this year’s flu shot was not the best match for some of the flu strains circulating this year.†That problem is not unique to Massachusetts, the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), which have to predict what flu strains to cover, missed on two out of three this year. “That guess is made by mid-summer in the Northern Hemisphere and vaccine production is based on these projections. Flu mutates frequently and as new strains emerge we must prepare new vaccines,†says Dr. Jim Wilde, professor of pediatrics and emergency medicine at the Medical College of Georgia. Dr. Wilde, who has a long standing interest in influenza and has published numerous articles based on his research, tells Infection Protection, “there is a worldwide network of people who monitor for the emergence of new strains of flu. Wrong guesses occur every few years. This year they guessed wrong on the B strain and on one of the A strains.â€
The flu vaccine is reformulated every year from three viral strains including two types A strains and one type B strain. In view of this year’s mismatch, the FDA advisory committee, following the lead of the WHO, is recommending that all three strains be changed for next year. Ms. Rheaume, of the Massachusetts DPH, tells Infection Protection that they have already received the 2008-09 recommendations. Changing all three strains is “unprecedented†and raises the question of whether the flu strains are drifting and shifting too quickly for accurate predictions.
Professor Sheldon Jacobson, Willett faculty scholar at the University of Illinois, is an operations researcher with expertise in supply chain management issues for vaccine distribution and stockpiling. “The key question is whether this represents a onetime aberration or the beginning of a new trend. Additional research and data collection will be needed to address this question,†he tells Infection Protection.
One of the possible problems in growing three new strains for next year’s vaccine is that some flu strains grow slowly in the laboratory. Dr. Nancy Cox, director of the CDC influenza division notes that, “One of the great limiting factors is how well the virus strains grow, and of course when you change strains, the growth properties are inherently unpredictable.†Professor Jacobson comments that, “vaccine manufacturers have already expressed concerns about the time frame to produce the 100 million plus doses needed for the 2008-2009 flu season. Given the time frame involved, and the nature of the new strains, it would not be a surprise to see flu vaccine supply chain problems and delays next year.â€
– by Dr. Chris Iliades, MD, Boston CorrespondentÂ

Nurse prepares a flu shot. Will it help? Image source: The Johns Hopkins University School of Public Health.
Posted: April 9th, 2008 under Diseases, Influenza.
Comments: none