Canadian women have a choice of two vaccines against HPV, the family of viruses that can cause cervical cancer, now that Health Canada has approved GlaxoSmithKline's vaccine, Cervarix.

The vaccine, which is expected to be available by the end of the month, will compete against Gardasil, a product of Merck Canada, which has been on the Canadian market since 2006.

Cervarix has been available in Europe since 2007, and was approved in the U.S. this past fall.  To date, 10 million doses have been distributed globally. Health Canada said its approval was based on a review of clinical trials on nearly 30,000 women.

The competing vaccines will be similarly priced, at about $400. Each vaccine requires three doses and are meant for girls and women aged 10 to 25, ideally before they become sexually active.

While there are differences between the two vaccines, each offers good protection against infection with the most dangerous strains of HPV, the Society of Gynecologic Oncology of Canada (GOC) said in a statement Tuesday.

The GOC added that each vaccine has had an excellent safety profile both in pre-market testing and after extensive use worldwide.

Cervarix is designed to protect against two human papillomavirus strains: HPV 16 and 18. Those strains are responsible for more than 70 per cent of cases of cervical cancer.

It also offers some protection against three other cancer-causing strains HPV 31, 33 and 45. Between them, the five strains account for more than 80 per cent of cervical cancer cases.

Gardasil also prevents infection with four strains of HPV 16 and 18, as well as HPV 6 and 11. The latter two strains cause about 90 per cent of cases of genital warts.

GSK reports that Cervarix is generally well tolerated. The most common side effects are pain, redness, and swelling at the injection site, fatigue, headache, joint pain and stomach upset.

In all, there are almost 200 strains of HPV, some that cause common warts on the skin, others that cause genital warts and that are sexually transmitted, and some that cause no symptoms at all.

While a number of strains have linked to cervical cancer, others have been linked to throat cancer, cancer of the head and neck, anal cancer, penile cancer and other cancers of the female genital tract such as vulvar and vaginal cancer.

In Canada, every province and territory now offers school-based HPV vaccination although the age group targeted varies by jurisdiction, from Grade 4 in Quebec through to Grade 8 in Ontario.

Currently, all school-based programs use Gardasil. But GSK officials say they are in discussions with several provinces and territories.

The GOC stresses that neither vaccine offers 100 per cent protection and women and sexually active girls should still go for regular Pap screening, regardless of whether they've been vaccinated.

"With vaccination, in combination with continued cervical screening, cervical cancer and its precursors are now highly preventable," the group said in a statement.

In Canada, there are approximately 1,400 new cases of cervical cancer and 420 deaths annually.