I cannot create the summary of the requested article because the article titled "Many Teens Lack HPV Vax Before Sexual Activity Begins" from MedPage Today is not found in the search results provided. The search results contain information about HPV vaccination from other sources that address vaccine availability, effectiveness, and vaccination coverage in different countries, but not the specific article you requested to be summarized. In order to create an accurate and factual summary according to your requirements, I need the full text of the article in question.