The virus causing the swine flu pandemic has spread to turkeys in Chile, slowed its spread in people in the Southern Hemisphere and in the United Kingdom, and is thriving in human populations in Alaska, Maine, and Japan. Drug companies are having difficulty growing the influenza A (H1N1) 2009 virus, which means that a vaccine against the disease will be in short supply this fall. So the novel H1N1 virus is behaving just as unpredictably as scientists predicted it would, said U.S. health officials at a press briefing today. “The behavior of this virus is still uncertain,” said Jesse Goodman, deputy commissioner of the U.S. Food and Drug Administration, repeating what has become this pandemic’s mantra.
Having a vaccine supply to protect people from the virus—which is no more virulent than seasonal flu but, in an unusual twist, mainly causes severe disease in younger people—remains the most pressing issue. At this point, the U.S. government expects manufacturers to deliver 45 million to 52 million doses of the vaccine by mid-October, said Jay Butler, head of the H1N1 task force for the U.S. Centers for Disease Control and Prevention. That is only about one-third of the amount that CDC earlier expected would be ready by then, although Butler stressed that more should become available each week, adding up to 195 million doses by the end of the year. “Everybody is doing the best they can to get as much vaccine available as soon as possible,” said Butler, “so the numbers can be subject to change.”
Bill Hall, a spokesperson for the Department of Health and Human Services, told ScienceInsider that four of the five companies it contracted to make the vaccine have taken “longer than expected” to make the viral antigen needed for the final product. In addition to growth problems with the virus, Hall noted that one vaccine maker is still making seasonal flu vaccine and has yet to switch over to production of the novel H1N1 product. Another vaccine maker, based in Australia, has devoted its initial supply to that country, which is in the winter season and combating its own substantial outbreak. There also have been delays in producing “potency reagents” that are used to test the vaccine, he said.
The CDC’s Advisory Committee on Immunization Practices last month issued recommendations on how to prioritize distribution of the vaccine if shortages exist, and those were published today in the Morbidity and Mortality Weekly Report.
One aspect to the pandemic has, so far, gone as planned: clinical trials of the new vaccines. The U.S. National Institute of Allergy and Infectious Diseases (NIAID) is coordinating five different trials at eight different sites around the country, which are testing whether two doses of the vaccine will be necessary to stimulate a robust immune response. “We expect first dose data somewhere around mid-September, if all goes well—and things seem to be going well—second dose data somewhere around mid-October,” said NIAID Director Anthony Fauci at the press conference. “There are no red flags regarding safety,” Fauci added.
Meanwhile, Chile reported yesterday that the virus had infected two flocks of turkeys near Santiago. This is the first report of the virus in birds, although pig herds in several countries have been infected, presumably by human-to-swine transmission. “Influenza viruses are always doing unpredictable and surprising things, although isolation of this virus from turkeys may not be that surprising, because the swine characteristics of this virus—this may sound funny to say—can have the capacity to infect turkeys,” said CDC’s Butler. Indeed, other swine influenzas have infected turkeys. One concern is that turkeys may become co-infected with the pandemic virus and other strains, leading to a new, more virulent virus that infects humans, but Butler said that this had never been observed to date.
Although uncertainties certainly will remain, Butler stressed that the U.S. government was doing everything it could to limit the harm caused by the virus. “We can't stop the tide of flu any more than we can turn a hurricane in its course or stop the earth shaking during an earthquake, but we can mitigate the effects and help prevent people from becoming severely ill by preparing well and acting effectively,” he said.