HPV-related cancers and diseases
Human papillomavirus (HPV) is a DNA virus of the family Papillomaviridae with more than 200 types, over 40 of which are sexually transmitted. Gardasil 9 (against 9 types: 6, 11, 16, 18, 31, 33, 45, 52, 58) is the best tool to prevent almost all dangerous HPV-related diseases and cancers in both men and women.
Transmission
Spread mainly through sex (vaginal, anal, oral) and skin-to-skin contact in the genital area. It can also spread via hands or sex toys, or from mother to child during vaginal birth. Condoms reduce the risk but do NOT give 100% protection, because the virus spreads through areas of skin around the genitals that condoms do not cover.
Symptoms
Most people infected with HPV (>80%) have no symptoms and clear the virus within 1–2 years thanks to their immune system.
- Low-risk HPV types (6, 11): cause GENITAL WARTS (condylomata) shaped like cauliflower, or papillomas on the vulva, penis, anus or throat; they cause itching and burning, bleed easily and keep coming back.
- High-risk HPV types (16, 18, 31, 33, 45, 52, 58…): persistent infection without symptoms for 5–15 years silently changes the epithelial cells into precancerous lesions (CIN 1, CIN 2, CIN 3), which then develop into invasive cancer.
- Signs of advanced cervical cancer: abnormal vaginal bleeding (after sex, between periods or after menopause), foul-smelling discharge mixed with blood, pelvic pain, pain during sex.
Complications
HPV causes about 5% of all cancers worldwide in both sexes (~965,000 new cancer cases each year):
- Cervical cancer: almost 100% of cases are linked to HPV (types 16 and 18 account for over 70%, and types 31, 33, 45, 52 and 58 for another 20%).
- Anal cancer: 85–90% of cases are linked to HPV (especially common in men who have sex with men, MSM).
- Vulvar and vaginal cancer in women (70–90% caused by HPV).
- Penile cancer in men (60% caused by HPV).
- Cancers of the oropharynx, tonsils and base of the tongue (over 70% of throat cancers).
- Recurrent respiratory papillomatosis in young children, passed on from the mother at birth.
People at high risk
- Males and females aged 9 to 45 (the golden age for vaccination is 9–14, before sexual activity begins and when the immune response is strongest).
- People who are sexually active, people with multiple partners, and people who have had one HPV type are still at high risk of the other types.
- Men who have sex with men (MSM) have a many times higher risk of anal and throat cancer.
- Immunocompromised people, people living with HIV, organ transplant recipients.
Preventive vaccines
- Gardasil 9 – Recombinant 9-valent HPV vaccine
- Gardasil – Recombinant quadrivalent HPV vaccine
Q&A
Does the HPV vaccine cause infertility in girls or women?
ABSOLUTELY NOT. This is a false rumour spread on social media. The WHO Global Advisory Committee on Vaccine Safety (GACVS) and the US Centers for Disease Control and Prevention (CDC) have carried out very large cohort studies following millions of women after HPV vaccination for nearly 20 years. The results confirm that the HPV vaccine does not cause primary ovarian insufficiency, does not reduce fertility and does not cause infertility. On the contrary, vaccination prevents precancerous lesions that would otherwise need treatment by cervical conisation (LEEP), a procedure that can later lead to cervical insufficiency, miscarriage or premature birth.
Source: Book: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine & MSD, 2024)
Should people who are sexually active or have had HPV infection still get vaccinated?
YES, THEY SHOULD. Even after becoming sexually active or being infected with one or more HPV types, very few people are infected with all 9 types covered by Gardasil 9 at the same time. Vaccination protects against the other high-risk HPV types they have not been exposed to, and also prevents reinfection with the same type after the body has cleared it, because natural immunity after HPV infection is weak and does not produce lasting protective antibodies.
Source: Book: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine & MSD, 2024)
Is an HPV DNA test or Pap smear needed before HPV vaccination?
NOT AT ALL. All reputable health organisations (WHO, US CDC, Vietnam Association of Preventive Medicine) recommend that no HPV DNA test or gynaecological examination is needed before HPV vaccination. Screening is for the early detection of precancerous lesions at regular intervals; it is not a condition for deciding whether someone can be vaccinated.
Source: Book: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine & MSD, 2024)
Why do men also need the HPV vaccine?
Men need the HPV vaccine for 4 key medical reasons:
1. HPV infection is as common in men as in women, but men clear the virus more slowly and produce fewer natural antibodies than women.
2. There is NO regular screening for men (like the Pap smear for women); HPV-related lesions in men are usually only found once they have become lumps or cancer.
3. HPV causes 90% of genital warts, 60% of penile cancers, 90% of anal cancers and more than 70% of oropharyngeal cancers in men.
4. Vaccinating men stops them from passing the virus on to their sexual partners in the community.
Source: Book: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine & MSD, 2024)
What is the minimum interval between HPV vaccine doses? What if a dose is given early?
The minimum interval rules are strict:
- 2-dose schedule (9–14 years): dose 2 must be at least 5 MONTHS (150 days) after dose 1. If dose 2 is given less than 5 months after dose 1 (for example after only 2 or 3 months), it does NOT COUNT towards completing the 2-dose schedule, and a THIRD DOSE is required (at least 3 months after dose 2).
- 3-dose schedule (15–45 years): the minimum interval between doses 1 and 2 is 1 MONTH (4 weeks); between doses 2 and 3 it is 3 MONTHS (12 weeks); and dose 3 must be at least 5 MONTHS (150 days) after dose 1. A dose given before the minimum interval is considered invalid and must be repeated.
Source: Gardasil 9 prescribing information & the HPV Q&A book
If an HPV vaccination schedule is interrupted for a long time (5–10 years), does it have to start again?
THERE IS NO NEED TO START AGAIN. The immune system keeps memory B lymphocytes. However long the interruption (even 5 or 10 years), the person only needs to receive the missing doses to complete the schedule; the doses already given remain valid.
Source: Book: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine & MSD, 2024)
What should be done if pregnancy is discovered after HPV vaccination? Does the pregnancy need to be terminated?
THERE IS NO INDICATION AT ALL FOR TERMINATING THE PREGNANCY. The HPV vaccine is a non-live recombinant vaccine (it contains only empty L1 protein shells and no viral genetic material, RNA or DNA). Global pregnancy surveillance data show that the rates of miscarriage and birth defects in women vaccinated by mistake during pregnancy are no different from the natural rates in the community. What to do: postpone the remaining doses, continue normal antenatal care, and complete the remaining doses after the baby is born.
Source: US CDC & Vietnam Association of Preventive Medicine
Can someone who has had all 3 doses of quadrivalent Gardasil also get Gardasil 9?
YES. People who have had all 3 doses of quadrivalent Gardasil (types 6, 11, 16, 18) and want to extend protection to 5 additional high-risk types (31, 33, 45, 52, 58) can receive the full 3-dose Gardasil 9 schedule at 0, 2 and 6 months. The recommended interval is at least 12 months after the last Gardasil 4 dose.
Source: Gardasil 9 prescribing information & the HPV Q&A book
Should women who have had cervical conisation (LEEP) for CIN 2/3 get the HPV vaccine?
IT IS STRONGLY RECOMMENDED. Clinical studies show that women who receive the HPV vaccine after conisation for precancerous lesions (CIN 2, CIN 3) have a 60–80% lower risk of recurrent lesions than those who are not vaccinated. The best time to vaccinate is just before or just after the procedure.
Source: Book: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine & MSD, 2024)
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