THURSDAY, July 23 (HealthDay News) -- U.S. officials hope to have 160 million doses of injectable swine flu vaccine on hand by October, with more doses coming in the form of a nasal spray.
Since immunization is expected to depend on each person getting two doses spread a month apart, the amount of vaccine will still only cover a fraction of the population, but more is expected to arrive in the following months, the Associated Press reported Thursday.
Earlier in the day, the U.S. Food and Drug Administration convened a meeting with the world's five leading flu vaccine makers to assess how many doses might be available. Jerry Weir, an FDA official charged with overseeing vaccine production, told the AP that the H1N1 swine flu vaccine is proving more difficult to grow in the standard way (using chicken eggs) than typical seasonal flu vaccines. In fact, the yield is just 30 percent of normal.
The Department of Health and Human Services is responsible for buying up and distributing new vaccine stocks. Robin Robinson, who helps direct the HHS effort, told the AP that his team is keeping the production slowdown in mind as HHS buys and distributes new vaccine stocks.
But there was brighter news, as well. Maryland-based MedImmune Inc. told U.S. officials on Thursday that it expects to have 14 million doses of a swine flu version of its FluMist nasal spray vaccine ready to distribute across the United States by October, and would have even more available if it could fill its spray devices any faster. Tens of millions more doses will be ready to be bottled, the company said, and it's possible that a sprayer wont even be necessary -- it may be enough to administer droplets of the vaccine into the nose.
"A dropper instead of a sprayer works well," MedImmune vice-president Dr. Ben Machielse told the AP. MedImmune said it plans to begin trials in August to make sure the H1N1 version of the nasal vaccine has no more side effects than the vaccine for the seasonal flu.
Also on Thursday, experts at the U.S. Centers for Disease Control and Prevention said that the virus has not yet mutated to become more dangerous, although they continue to follow its progress globally, the AP reported. Dr. Nancy Cox, chief of CDC's influenza division, called the lack of genetic variation in the H1N1 strain "quite surprising" given the pathogen's quick spread.
In the meantime, the United States is readying its first human trials of an experimental vaccine to protect against the H1N1 swine flu virus, officials announced Wednesday.
Two potential vaccines will be tested at eight institutions around the country under the auspices of the National Institute of Allergy and Infectious Diseases (NIAID), officials said.
The purpose of the trials, said NIAID Director Dr. Anthony S. Fauci in a prepared statement, is to "determine whether the vaccines are safe and to assess their ability to induce protective immune responses. These data will be factored into the decision about how and if to implement a 2009 H1N1 flu immunization program this fall."
The announcement followed Tuesday's revelation that two Australian biotechnology companies have started inoculating adult volunteers in the world's first H1N1 swine flu vaccine trials. Experts hope those trials, as well as the trials planned in the United States, will produce an effective shot against the virus that has so far killed more than 700 people worldwide.