Allergic reactions to Gardasil uncommon: study

LONDON (Reuters) - A study of Merck & Co Inc's cervical cancer vaccine Gardasil found that allergic reactions were uncommon and most young women can tolerate subsequent doses, Australian researchers said on Wednesday.

The research involved 25 Australian girls with suspected hypersensitivity to the vaccine which was administered as part of a national immunization program to all females aged 12 to 26 in the country beginning in 2007.

More than 380,000 doses of the vaccine have been given under the program, Sharon Choo of the Royal Children's Hospital in Melbourne and colleagues wrote in the British Medical Journal.

"Our clinical recommendation is that females with suspected hypersensitivity to the quadrivalent vaccine should be evaluated before receiving more doses, and any challenges with the same vaccine should be carried out in a supervised setting," they said.

Choo and colleagues noted some components of Merck's treatment -- such as aluminum salts and yeast -- have been associated with allergic reactions.

But skin tests of the 25 girls with suspected hypersensitivity showed that only three of them experienced probable reactions to the jabs.

The researchers also noted that suspected reactions such as hives are often "idiosyncratic" and do not increase the risk of adverse reactions in subsequent shots.

Gardasil and GlaxoSmithKline Plc's Cervarix are designed to be given to girls and young women to protect against cancer-causing strains of the sexually transmitted human papillomavirus (HPV), which can cause cervical cancer.

Gardasil targets four strains of HPV -- two responsible for cervical cancer and two causing the less serious condition of genital warts. Glaxo's product targets the two cancer strains.

In October, the U.S. Centers for Disease Control and Prevention reported that girls and young women given Gardasil were no more likely than usual to faint, have an allergic reaction, blood clot or other adverse reaction.

The report was based on 375,000 doses of the vaccine given from August 2006 to July 2008 after the agency had received 10,326 reports of adverse events following HPV vaccination in the United States.

(Reporting by Michael Kahn; Editing by Maggie Fox and Elaine Hardcastle)