FDA approves Sanofi's intradermal flu vaccine

May 10, 2011 (CIDRAP News) – Sanofi Pasteur's intradermal influenza vaccine, which involves a shallow needle prick into the skin instead of deep into muscle tissue, has been approved by the US Food and Drug Administration (FDA), the company announced today.

Similar Sanofi vaccines have been licensed in Europe, Canada, Australia, and other countries, but Fluzone Intradermal will be the first flu vaccine of its kind in the United States, the company said. It was licensed for adults between 18 and 64 years old.

The vaccine will be available for the 2011-12 flu season, the company said.

"The microinjection delivery system utilized in Fluzone Intradermal vaccine provides reliable and easy delivery of the vaccine into the dermal layer of the skin, an attractive site for immunization," Olivier Charmeil, Sanofi Pasteur's president and CEO, said in a press release. He said the vaccine may help improve adult influenza immunization rates.

The dermal layer of the skin contains a high concentration of dendritic cells, which play a key role in generating immune responses, the company said. In clinical trials Fluzone Intradermal induced immune responses similar to those generated by Fluzone vaccine given intramuscularly (IM).

The new vaccine has an "ultra-fine" needle 1.5 millimeters (0.06 inch) long, versus 25 to 38 mm (1 to 1.5 inches) for intramuscular vaccines, according to Sanofi. The vaccine contains 9 micrograms (mcg) of hemagglutinin per flu strain in a 0.1-milliliter dose, as compared with 15 mcg per strain for conventional flu vaccines.

The FDA approval of Fluzone Intradermal was based on a phase 3 clinical trial in which 2,855 adults received the vaccine and 1,421 adults received the IM version, Sanofi reported. The results—similar immune responses to both vaccines—were reported in October 2010 at the annual meeting of the Infectious Diseases Society of America.

Systemic reactions were similar with both vaccines, but local reactions were a little more common with the intradermal product, officials said. Local reactions reported by vaccinees when asked included redness in more than 75%, swelling (over 50%), pain (over 50%), and itching (over 40%), according to the press release.

"The primary difference is that Fluzone Intradermal is given at the surface of the skin, so when you first give the vaccine there may be a little bit of a wheal or a bubble for a few minutes," Sanofi spokeswoman Donna Cary told CIDRAP News. "Solicited local reactions—redness, swelling, and others—were slightly higher with the intradermal, because you can see it." But she said the reactions lasted a few days at most and the vaccine was well accepted.

Cary said Sanofi has had a very positive response to its intradermal flu vaccines in Australia, Argentina, and other countries, with surveys finding that 95% or more of vaccinees wanted to receive the vaccine again the next year. She said use of the vaccine in Europe "is just getting going now."

"Australia was really the first country where it was launched and widely used, and it's had really good acceptance," she said.

Cary said the supply of Fluzone Intradermal is likely to be modest this year. "Because it's getting licensed later, we probably will have limited supplies for the US this year. It won't be available probably until early October, and our goal for this year is to get people to try it. We think if they try it, they'll like it."

"We still have to go to the ACIP [Advisory Committee on Immunization Practices] in June to get it added to the recommendations and still need to put in place all the reimbursement mechanisms," she added. "That process tends to follow the ACIP recommendations."

Sanofi's list price for Fluzone Intradermal is $15.50 per dose, as compared with $10.42 per adult dose for regular Fluzone, Cary reported. The list price for Fluzone High-Dose, intended for elderly people, is $25, she said.

In some countries the company's intradermal vaccines, marketed as Intanza or IDflu, are licensed for elderly as well as younger adults, Cary noted, adding, "Here in the US we have the high-dose vaccine licensed—the immune response for those adults is better with the high-dose vaccine. In other countries they don't have the high-dose vaccine."

Regarding the possibility of using the vaccine in children, Cary said the company needs to do more research. "One of the challenges with children is there isn't the same uniformity of skin thickness, among other things, so additional studies are needed to license it for children," she explained.

See also:

May 10 Sanofi press release

Feb 26 CIDRAP News story "Europe approves Sanofi's intradermal flu vaccine"

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