Few adverse reactions to cervical cancer vaccine

WASHINGTON, Oct 22 (Reuters) - Girls and young women given Merck and Co's (MRK.N) Gardasil vaccine to prevent cervical cancer were not any more likely than usual to faint, have an allergic reaction, blood clot, or other adverse reaction, federal officials said on Wednesday.

The vaccine does not cause any more cases than usual of eight different adverse events, the U.S. Centers for Disease Control and Prevention found.

The report to the Advisory Committee of Immunization Practices was based on 375,000 doses of the vaccine given from August 2006 to July of 2008.

"As with all approved vaccines, CDC and FDA (U.S. Food and Drug Administration) will continue to closely monitor the safety of the HPV vaccine," the CDC said in a statement.

Gardasil protects against the four types of human wart virus, also known as human papilloma virus or HPV, that are most likely to cause cervical cancer -- a highly deadly type of cancer.

Because HPV is sexually transmitted and very common, most people are infected as young adults and to protect them, the vaccine must be given before girls are sexually active. This has led to some controversy.

The CDC said it received 10,326 reports of adverse events following HPV vaccination in the United States.

"Of these reports, 94 percent were reports of events considered to be non-serious, and 6 percent were reports of events considered to be serious," the CDC said. These included 27 deaths.

Such reports do not necessarily show that a vaccine has caused a disease or event -- they simply show that someone fainted, became ill or had an allergic reaction around the time they also received the vaccine.

"Reports of non-serious adverse events after HPV vaccine have included fainting, pain and swelling at the injection site (the arm), headache, nausea and fever," the CDC said.

"Fainting is common after injections and vaccinations, especially in adolescents."

Some of the serious events included Guillain-Barre Syndrome, a rare disorder that causes muscle weakness. It can be caused by a number of infections.

"There has been no indication that the HPV vaccine increases the rate of GBS in girls and women above the rate expected in the general population, whether or not they were vaccinated," the CDC said.

Eleven of the deaths were traced to diseases such as diabetes or meningitis and unrelated to the vaccine, while the others were being investigated or did not provide enough information to assess, the CDC said.

GlaxoSmithKline (GSK.L) has an HPV vaccine called Cervarix, which is used mostly in Europe. (Reporting by Maggie Fox; Editing by Julie Steenhuysen and Jackie Frank)