Vaccine to Fight New Bird Flu Strain Could Be Elusive
April 12, 2013 Leave a comment
April 11, 2013, 8:09 p.m. ET
Vaccine to Fight New Bird Flu Strain Could Be Elusive
By BETSY MCKAY
Developing a vaccine to protect people from the new H7N9 flu virus that recently emerged in eastern China could prove to be especially difficult, flu experts from the U.S. Centers for Disease Control and Prevention reported in a paper Thursday.
As with many new flu viruses, it isn’t clear yet whether the new flu will create only “sporadic human infections from an animal source” or whether it will “signal the start of an influenza pandemic,” CDC flu scientists Timothy Uyeki and Nancy Cox wrote in an article published online in the New England Journal of Medicine.
In addition, they wrote, “there are many challenges to making H7N9 vaccines available.” Vaccines against H7 avian flu viruses that have already been studied haven’t produced a strong immune response in humans, they wrote. And like any new vaccine, it would likely take many months to produce and distribute, they wrote, adding “extensive efforts” to develop vaccines are under way.They called for intensified surveillance in both people and animals to determine whether the new virus is transmitting from one person to another and to answer other questions. So far, scientists say no evidence has been found of person-to-person transmission of the disease.
The number of patients in China confirmed with H7N9 flu had climbed to 38 as of Thursday, including 10 deaths, according to the World Health Organization. More than 760 people who were in close contact with those confirmed cases are being closely monitored, the Geneva agency said.
In another article published Thursday, also in the New England Journal of Medicine, a team of Chinese scientists said the new H7N9 virus was likely transmitted to people directly from birds rather than mammals. Chinese officials destroyed flocks of poultry late last week, after learning that some patients had had contact with birds before becoming ill.
The scientists hypothesized that the virus formed, or “reassorted,” from three different avian viruses. The new virus contains genes resembling those found in viruses circulating in wild birds, ducks, and a brambling in Beijing, they wrote.
“Currently, there are no data to suggest that this reassortment occurred in a mammalian host,” they wrote.
The scientists drew their conclusions from studying virus samples from the first three H7N9 patients. Those patients, ages 87, 27, and 35, all died. All three had underlying medical conditions, including hypertension, hepatitis B, and chronic obstructive pulmonary disease.
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