FRIDAY, Aug. 21, 2009 (HealthDay News) -- As the H1N1 swine flu virus continues to circle the globe, producing minor infections similar to seasonal flu, U.S. health officials said Friday that they were on track for a viable vaccine by the fall, with early indications that the shot is safe.
The new vaccine is now in a series of clinical trials, the results of which should be completed between mid-September and late October. Officials said they hope to have 45 million to 50 million doses by mid-October and 195 million doses by year's end.
"A number of clinical trials were designed and have begun to ask fundamental questions that would inform how we would use the virus, the proper dose, some early safety data as well as the use of the vaccine in certain populations," Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said during an afternoon press conference.
There are five trials, Fauci said. One trial, which started in early August, is designed to determine the most effective dose of the vaccine and whether one or two doses will be needed. "We expect first-dose data in mid-September and second-doses data in mid-October," he said.
Early results for this first trial among adults have found the vaccine to be safe with no serious side effects, he added.
Another trial, also involving adults, is looking to determine the best timing for giving the vaccine for seasonal flu as well as the new H1N1 swine virus vaccine. A third trial that began a few days ago is testing the vaccine in children 6 months to 17 years old, Fauci said. Dosing information from this trial is expected in September and October, he said.
Trials are also planned involving pregnant women; they are scheduled to start in mid-September.
Finally, there will be a trial testing so-called adjuvants, which are additions to the vaccine to make it more effective. This trial is set to launch in mid- to late September, Fauci said.
The U.S. Centers for Disease Control and Prevention is making plans to distribute the swine flu vaccine when it becomes available. The agency has also issued its final recommendations for groups of people who should be vaccinated, Dr. Jay Butler, director of the agency's H1N1 Vaccine Task Force, said at the press conference.
These groups include "pregnant women, children and young adults aged 6 months to 24 years, as well as persons aged 25 to 64 who have medical conditions that put them at high risk for influenza-related complications," Butler said.
Health-care workers and people who live with or care for infants under 6 months of age, who are too young to be vaccinated, should also be vaccinated, he said.
While the H1N1 swine flu is expected to return to North America in the fall, right now flu activity in the United States is low, and it appears to be winding down in the Southern Hemisphere, where winter is coming to a close, Butler said.
"To date there have been 7,963 hospitalizations and 522 deaths [in the United States] that have been laboratory confirmed as caused by novel H1N1 flu," Butler said. "It is important to keep in mind that these numbers radically underestimate the number of cases that actually occur, because many cases go without testing," he added.
Most states are reporting low levels of swine flu activity, Butler said. The exceptions are Alaska and Maine, he said.
Earlier this week, federal officials announced that there will only be an estimated 45 million doses of vaccine on hand by Oct. 15, rather than the originally anticipated 120 million doses. After mid-October, 20 million more doses of the vaccine will be shipped each week.
Officials attributed the delay to a less-than-expected yield of the vaccine substrate used to make the vaccine; egg cultures are the source of vaccine substrate.
Another factor contributing to the delay is not having enough manufacturers to actually package the vaccine, according to published reports.
In June, the World Health Organization declared the H1N1 swine flu a pandemic, the first such declaration in 41 years. The declaration was made not because the swine flu is particularly dangerous, but because it had become so widespread. To date, there have been 182,166 cases of infection worldwide and 1,799 deaths, the WHO Web site reported Friday.
In a potential worrisome development, Chilean officials on Friday announced the detection of the H1N1 strain in turkeys in that country, the Associated Press reported. Illness in the birds has been mild, but experts have worried that a more transmissible and virulent strain of human flu could emerge if H1N1 combines with an avian strain.
For more on H1N1 swine flu, visit the Flu.Gov.