Swine flu roundup: Vaccine testing on track

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Testing of the vaccine against the pandemic H1N1 influenza virus is on track and there have been ‘no red flags’ for adverse effects, said Dr. Antonhy Fauci, director of the National Institute of Allergy and Infectious Diseases, at a news conference today. The only observed problems have been some redness, swelling and soreness at the injection site -- the same as observed with seasonal flu and other vaccines. The first data on the immunogenicity of a single dose of the vaccine should be available by the middle of the September and data from two doses should be available a month later, he said.

Based on the lack of adverse effects in vaccination of the elderly, tests in children age 6 months to 17 years began Wednesday and Thursday, he said. Data from those trials should be available about two weeks after data from the first trials.

The United States expects to have 45 million to 52 million doses of the vaccine available by mid-October and as many as 195 million by the end of the year, said Dr. Jay Butler, director of the Centers for Disease Control and Prevention’s H1N1 vaccine test force, in the same news conference. The vaccine will be distributed to the states on the basis of population, he said, and distribution will be coordinated in the same manner as the government’s Vaccines for Children program -- although the program will have to enroll many more providers to ensure adequate distribution.

Butler said that there have so far been 7,963 hospitalizations and 522 deaths from laboratory-confirmed infections of pandemic H1N1 in the United States. About 75% of those hospitalized are under the age of 49, as are 60% of those who died. The current round of infection is slowing, he added, with only sporadic cases in all states except Alaska and Maine, which have widespread activity. ‘Reports of widespread influenza activity in August are very unusual,’ Butler noted, and emphasize how little is still known about the new virus. Officials believe there have been more than 1 million cases of swine flu in the United States to date.

Worldwide, nearly 1,800 people have died from complications of the virus, with more than 1,200 of them in Latin America, according to the World Health Organization. But flu activity is decreasing in the Southern Hemisphere, Butler said, as the conventional flu season winds down. Activity is also declining in the United Kingdom, which has had a severe outbreak of the virus, but is increasing in Japan -- for reasons that are not clear. A WHO official said earlier this week in China that there could be an ‘explosion’ of new cases this fall with cases doubling every three to four days for several months. Fauci said that the U.S. should expect an upsurge in new cases this fall as children return to school, but Butler said that an explosion of new cases is a ‘worst case scenario. Whether it will occur, I don’t think any of us know.’

Agricultural officials in Chile said this week that pandemic H1N1 virus has been found in two flocks of turkeys and that the animals were quarantined and have fully recovered. Officials have been wary about such infections because of the risk that the pandemic H1N1 virus could recombine with the H5N1 avian flu virus, which is much more deadly but not as readily transmissible in humans. Such a recombinant could theoretically possess the easy transmission of the current swine flu virus with the lethality of the bird flu. It could also recombine with seasonal flu, which is resistant to antiviral drugs such as Tamiflu -- thereby limiting options for treating and preventing swine flu infections.

Butler noted, however, that the isolation of the virus from turkey ‘is not that surprising’ because attributes of swine flu viruses help them infect turkeys. The virus was discovered because of a drop in egg production, not because turkeys were dying, and officials have seen no evidence of recombination. ‘The report did not raise any great concerns among us,’ he concluded.

-- Thomas H. Maugh II