There's a new HPV vaccine: here's what you need to know

We're only mid-way through February, but 2015 has already been quite a year for vaccine-related controversies. First came a troubling resurgence of measles, then a minor blowback against the HPV vaccine Gardasil. Administered mostly to girls and women between the ages of nine and 26, the shot protects against human papillomavirus (HPV). HPV isn't just the most common sexually transmitted infection in the world, either — it's also linked to several reproductive cancers. Now, eight years after its predecessor was first approved for use, Health Canada has green-lit Gardasil-9 — a new, more comprehensive iteration of the original immunization — for widespread distribution this spring. Here's what you need to know about the second-generation HPV vaccine:

• Gardasil-9 guards against genital warts, as well as cervical, vaginal, vulvar and anal cancers caused by nine different strains HPV; the original vaccine only targets four.
• Boys allowed: like its prototype, Gardasil-9 is a unisex shot.
• Research suggests that the nine-strain vaccine is safely tolerated by those who have already been immunized against the first four strains. (In other words, if you've had the first shot, you're probably okay to get the second.)
• A study sponsored by the pharmaceutical company Merck & Co. estimates Gardasil-9's effectiveness rate to be upwards of 97 per cent.
• Side effects are relatively consistent between Gardasil's two iterations — headaches, swelling, redness and pain at the injection site have been reported. Serious allergic reactions are rare.