Q1: What is the difference between quadrivalent and 9-valent vaccines?

A1: First of all, we must know that there are more than 100 strains of HPV in this world.  However, only some specific strains can cause cancer or anogenital warts.  The vaccines do not cover every strain of HPV.

Vaccine type Quadrivalent (4vHPV) 9-Valent (9vHPV)
Protection against HPV type 6, 11, 16, 18 6, 11, 16, 18, 31, 33 45, 52, 58

The strains which usually lead to cancer are 16, 18, 31, 33, 45, 52, 58 while the strains which often cause anogenital warts are 6 and 11

Q2: Can I still get the HPV vaccine despite I have already had sexual intercourses?

A2: Yes, getting the vaccine still gives more benefit than not getting one even after history of sexual intercourses in everyone; men, women, and LGBTQ+

Q3: I used to have anogenital warts or I’m currently getting treatment for anogenital warts.  Can I get the HPV vaccine now?  Will the anogenital warts come back after the vaccination?

A3: Yes, you can get the HPV vaccine.  There were some studies found that HPV vaccine can help with the treatment of anogenital warts.  However, there are not sufficient evidences regarding the prevention of anogenital wart recurrence.

Q4: Why do I still get warts on other areas like hands, feet, and extremities despite I’ve already had HPV vaccine?

A4: Because the HPV strains which cause warts in the mentioned areas are mostly type 1, 2, 3, 4, 10, 27, 57 and these strains were not made into vaccines.  Therefore, the vaccines cannot protected you against every kinds of warts.

Q5: Do I still need cervical cancer screening (Pap smear)?

A5: You should still get annual check for cervical cancer screening which is recommended for women from age of 21 to 65.  There is nothing 100% in medicine so it does not mean that you have zero chance of getting cervical cancer after HPV vaccination.

Q6: I’ve already gotten the first 2 shots but I forgot to get the last one on time.  Do I need to restart all over again?

A6: No, you can get the last shot without having to restart the course.  The last shot should be the same type as the first 2 shots.  For example, if you get the 9-valent vaccine for the first 2 shots then the last shot should be the 9-valent.


  1. Petrosky E, Bocchini JA Jr, Hariri S, et al. Use of 9-valent human papillomavirus (HPV) vaccine: updated HPV vaccination recommendations of the advisory committee on immunization practices. MMWR Morb Mortal Wkly Rep. 2015;64(11):300-304.
  2. Saslow D, Solomon D, Lawson HW, et al. American Cancer Society, American Society for Colposcopy and Cervical Pathology, and American Society for Clinical Pathology screening guidelines for the prevention and early detection of cervical cancer. J Low Genit Tract Dis 2012;16:175–204.
  3. Moyer VA; US Preventive Services Task Force. Screening for cervical cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med 2012;156:880–91, W312.
  4. Kang S, Kang S. Fitzpatrick’s Dermatology. New York: McGraw-Hill Education; 2019.
  5. Choi H. Can quadrivalent human papillomavirus prophylactic vaccine be an effective alternative for the therapeutic management of genital warts? an exploratory study. Int Braz J Urol. 2019;45(2):361-368. doi:10.1590/S1677-5538.IBJU.2018.0355
  6. Husein-ElAhmed H. Could the human papillomavirus vaccine prevent recurrence of ano-genital warts?: a systematic review and meta-analysis. Int J STD AIDS. 2020;31(7):606-612. doi:10.1177/0956462420920142

Written by Dr. Wipawan Vathananai MD (Glove Clinic, Bangkok, Thailand)