Swine Flu Vaccine Won't Be Ready Until October: CDC

But it's still not certain that a broad-based immunization program will be needed

FRIDAY, May 29, 2009 (HealthDay News) -- A vaccine for the H1N1 swine flu virus could be ready in October, if research and testing proceed on pace this summer, a leading U.S. health official said Thursday.

Candidate viruses have been shipped to vaccine manufacturers. But federal officials will have to monitor the safety and effectiveness of any vaccines produced, before full-scale production could begin, Dr. Anne Schuchat, the U.S. Centers for Disease Control and Prevention's interim deputy director for science and public health program, said during an afternoon press conference.

"If everything went really well it would not be until the fall before a vaccine would become available. We are saying at this point not before October," Schuchat said.

It's still not clear whether a swine flu vaccine is needed, Schuchat said. Any decision to move forward would be based on several factors, including the severity and spread of the virus and whether there's a safe and effective vaccine, she said.

So far, infections with the H1N1 swine flu virus continue to be mild and recovery is fairly quick, as is the case with seasonal flu, officials said. On Thursday, the CDC was reporting a total of 8,585 cases in 48 states, including 12 deaths. Testing has found that the virus remains susceptible to two common antiviral drugs, Tamiflu and Relenza, according to the CDC.

Schuchat said the newly identified H1N1 virus continues to behave much like seasonal H1N1 viruses, which may partly explain why this flu strain affects more younger people. "Seasonal H1N1 often causes more disease in younger people, compared with the other strains that can be more common in older people," she said.

Also, when seasonal H1N1 flu strains dominate there are fewer deaths than when H3N2 flu strains dominate, Schuchat said.

"There will be decisions later in the summer or early fall about whether to actually finish the vaccine and how large-scale the production might be, and whether or not an immunization program is going to be recommended for some or much of the population," she said.

Some older people may have partial immunity to the H1N1 swine flu virus because of possible exposure to another H1N1 flu strain circulated prior to 1957. So far, 64 percent of cases of swine flu infection in the United States have been among people aged 5 to 24, while only 1 percent involves people over 65, officials said last week.

One major difference in the new H1N1 strain is that it is spreading just at the time when the seasonal flu season is ending, Schuchat said. "This virus is circulating much later than annual flu viruses. We are really not seeing much of any seasonal flu viruses any more, but we're continuing to see this strain circulate, even though we are almost at June," she said.

During the next few months, scientists will be looking to see if the swine flu virus mutates or becomes resistant to antiviral medications, or is more easily spread among people, she said. The flu season is winding down in the Northern Hemisphere but is just beginning in the Southern Hemisphere.

Schuchat said there's no way to tell now if the H1N1 virus will be more virulent when -- and if -- it returns to the Northern Hemisphere with the approach of winter. "Whether it will dominate among the seasonal flu viruses or whether it will disappear is not predictable right now," she said Tuesday.

The World Health Organization said Thursday that 48 countries have reported 13,398 cases of infection, including 95 deaths, most of them in Mexico, where the outbreak began.

U.S. Human Cases of H1N1 Flu Infection
(As of May 29, 2009, 11:00 AM ET)
States # of
confirmed and
probable cases
Deaths
Alabama
71
Arkansas
6
Arizona
540
3 deaths
California
553
Colorado
68
Connecticut
149
Delaware
115
Florida
165
Georgia
28
Hawaii
71
Idaho
12
Illinois
1002
2 deaths
Indiana
138
Iowa
71
Kansas
34
Kentucky**
50
Louisiana
114
Maine
11
Maryland
48
Massachusetts
416
Michigan
229
Minnesota
47
Mississippi
13
Missouri
29
1 death
Montana
14
Nebraska
43
Nevada
84
New Hampshire
35
New Jersey
72
New Mexico
97
New York
553
4 deaths
North Carolina
14
North Dakota
6
Ohio
18
Oklahoma
67
Oregon
132
Pennsylvania
123
Rhode Island
13
South Carolina
41
South Dakota
6
Tennessee
100
Texas
1403
3 deaths
Utah
122
1 death
Vermont
3
Virginia
29
Washington
575
1 death
Washington, D.C.
14
Wisconsin
1430
Wyoming
1 case
TOTAL*(49)
8,975 cases
15 deaths
*includes the District of Columbia
**One case is resident of Ky. but hospitalized in Ga. Source: U.S. Centers for Disease Control and Prevention

More information

For more on swine flu, visit the U.S. Centers for Disease Control and Prevention.

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