Swine Flu Immunity May Be Delayed by Vaccine Choice (Update1)

http://www.bloomberg.com/apps/news?pid=20601087&sid=aj7B0KK3MuZk

By Tom Randall

Sept. 3 (Bloomberg) -- Americans may need two vaccine doses instead of one to be immunized against swine flu because officials plan to exclude ingredients used to boost immune responses in shots made by Novartis AG and GlaxoSmithKline Plc.

Novartis AG today reported that a single dose of its vaccine, which relies on a shot-boosting ingredient known as an adjuvant, safely provoked a strong immune response in a trial of 100 healthy volunteers. The formulation favored by the U.S. doesn’t use an adjuvant, and a second vaccine dose is more likely to be required, said Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention.

The U.S. paid Novartis, based in Basel, Switzerland, and London-based Glaxo more than $415 million for emergency stockpiles of adjuvant, which isn’t approved by the Food and Drug Administration. Vaccines are slated to arrive in mid- October, a time that health officials say could be the peak of outbreaks. A second dose would need to be given three weeks after the first, delaying immunity.

“We expect that the likelihood of needing two doses of vaccine that’s not adjuvanted is higher than with an adjuvanted vaccine,” Frieden said today in a conference call. “We don’t anticipate that we’ll be using adjuvanted vaccine in most of the scenarios that we anticipate now, though that could change.”

Antibodies From First Shot

The Novartis vaccine trails are the first glimpse of tests in more than 6,000 adults and children that the company is conducting. A single shot induced the body to produce protective antibodies within two weeks, Novartis said. Sufficient levels were achieved in 80 percent of patients after the first shot, and 90 percent of patients after a second shot.

“The pilot trial results are encouraging,” said Andrin Oswald, chief executive officer of Novartis Vaccines and Diagnostics, in an e-mailed statement. “This is important information for public health authorities who prepare for vaccination in the coming months with limited vaccine supply.”

The U.S. Health and Human Services Department is conducting its own vaccine tests, and data from clinical trails to assess dosing and effectiveness will start to become available in mid- September, health officials reported Aug. 21. Full results from the two-dose trials won’t be available until mid-October. The U.S. anticipates a two-dose vaccine, especially among children, the CDC’s Frieden said.

Controversial in U.S.

Adjuvants are controversial because some studies show they cause immune disorders in mice. The U.S. Health and Human Services Department declared a public health emergency over swine flu in April, giving the Food and Drug Administration the power to allow the use of unapproved medical products including adjuvants.

The U.S. never had to consider the risks of adjuvants in flu shots because the vaccines have “worked so tremendously well” without the additives, said Lone Simonsen, research director in the department of global health at George Washington University in Washington, in July. Flu vaccines with adjuvants have been used safely “for years” in Italy and Spain, Simonsen said.

The U.S. has been slow to approve the use of adjuvants because of safety concerns, and for fear of giving Americans an excuse to avoid getting the shots, said John Treanor, a University of Rochester researcher, in July as well.

To contact the reporters on this story: Tom Randall in New York at trandall6@bloomberg.netCarey Sargent at csargent3loomberg.net; Paul Verschuur at pverschuur@bloomberg.net

Last Updated: September 3, 2009 17:25 EDT