U.S., Australian researchers say single H1N1 vaccine dose protects adults against virus

Sep 11 2009

The results of clinical trials have shown one dose of the H1N1 (swine) flu vaccine is enough to offer adults protection against the virus, U.S. and Australian researchers said Thursday, the Associated Press reports (Neergaard, 9/11).

"That means it should be possible to vaccinate — well before the flu's expected midwinter peak — all the 159 million people that the Centers for Disease Control and Prevention estimate are in the high-risk groups: pregnant women, people under 24 years old or caring for infants, people with high-risk medical conditions and health-care workers," the New York Times writes (McNeil, 9/10).

In the clinical trial of the H1N1 vaccine, conducted by the Australian drug maker CSL, Ltd., and published Thursday in the New England Journal of Medicine, researchers tested the immune response of 240 adults, ages 18 to 64, who received a single, standard 15-microgram dose of the vaccine, CNN reports (9/10). The test revealed "between 75 percent and 96 percent of vaccinated people should be protected with one dose — the same degree of effectiveness as the regular winter flu shot," according to the AP (9/11).

The first results out of the U.S.-run clinical trials, scheduled to be released Friday, also found a single dose of the H1N1 vaccine offered protection within eight to ten days, Bloomberg reports. However, because the studies focused on adults, who naturally have stronger immunity than children, additional trials are needed to determine the best dose regimen for children (Randall, 9/11). NPR also reports on the latest on the single-dose H1N1 vaccine (Silberner, 9/11).

Reuters reports on a second New England Journal of Medicine study, where the pharmaceutical company Novartis confirmed that a single dose of H1N1, when combined with an adjuvant, could safely provoke an immune response to the virus, reports. The studies, which come one week after the Chinese company Sinovac first reported its clinical trials found a single H1N1 dose could protect against the virus, may help "lay to rest fears about the logistical nightmare of trying to vaccinate hundreds of millions of people globally with two doses of H1N1 vaccine -- given a month apart -- in addition to a single recommended dose of seasonal influenza vaccine," the news service writes (Fox, 9/10).

"The results were welcomed by officials at the World Health Organization, which has been particularly concerned about providing enough vaccine to poorer countries," the Washington Post reports. "If this is true, this is quite encouraging," WHO spokesperson Gregory Hartl said. "If you only need one shot instead of two, the vaccine will go twice as far. Twice as many people will be able to get the vaccine" (Stein, 9/11).

TIME examines the results of a study published Friday in the journal Science, which "makes the case for widespread and speedy immunization, suggesting that doing so could stifle the pandemic." For the study, researchers used a model to predict how H1N1 will spread in coming months and found "by first vaccinating children, then adults, until 70% of the U.S. population is covered, officials would be able to all but stop the pandemic," the magazine writes. However, "the problem is that, according to the model, vaccinations would have to begin by mid-September — but the first batch of the vaccine isn't due until October" (Park/Walsh, 9/10). HealthDay News/Atlanta Journal-Constitution includes comments by the lead authors of the study, who emphasize the importance of getting the H1N1 vaccine even if it will not fully prevent a fall pandemic (9/11).

MedImmune's H1N1 Vaccine To Be Shipped To U.S. By End Of September, Company Says

A spokesperson for the pharmaceutical company MedImmune on Thursday said the company plans to begin shipping its inhaled vaccine that offers protection against H1N1 to the U.S. government by the end of September, Reuters reports in a separate story. The company "has submitted safety data for their nasal spray swine flu vaccine to the U.S. Food and Drug Administration," the news service writes (9/10).

U.S. Begins H1N1 Vaccine Trial In Pregnant Women

In related news, USA Today reports on the recent launch of a clinical trial to test the H1N1 vaccine in pregnant women in the U.S. One hundred and twenty women between the ages of 18 and 39 who are in their second or third trimester of pregnancy will participate in the study, according to the newspaper (Sternberg, 9/10).

Australian Government Confirms Country's First Case Of Tamiflu-Resistant H1N1

The Western Australia state government on Friday confirmed a 38-year-old Perth man to be the country's first Tamiflu-resistant case of H1N1, Reuters reports. According to a government spokesperson, there is no evidence the Tamiflu-resistant strain has spread to the patient's family members or hospital staff (9/11). In related news, CDC researchers believe they have identified the first case of transmission of Tamiflu-resistant H1N1 - between two girls at summer camp, the Los Angeles Times blog, "Booster Shots," reports. The findings appear in the Friday issue of the MMWR (Maugh, 9/10).

Chinese Health Ministry Official Warns H1N1 Could Infect 'Millions' In China

A Chinese health ministry official on Friday addressed growing concerns over the spread of H1N1 throughout the country, which has infected close to 7,000 people so far, Agence France-Presse reports. "According to expert estimates, our nation during the autumn season might have several tens of millions infected with A(H1N1)," Liang Wannian, deputy director of the ministry's health emergency office, said during a press conference. "We will begin emergency inoculations in an active, stable and orderly manner," starting with those most at high-risk from the virus, Liang said. The vaccinations will be free to the public, the news service adds (Saiget, 9/11). In related news, Inter Press Service examines the race to mass-produce the H1N1 vaccine in Asia (Macan-Markar, 9/10).