HPV (human papillomavirus) spreads mainly through genital contact. The virus causes cancers of the cervix, vulva, vagina, anus, penis and throat, as well as genital warts. This article is based on the book Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam) and the HPV section of the book Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026).

What diseases HPV causes

High-risk types cause about 5% of all cancers worldwide in both sexes, an estimated 965,000 new cases in 2020. Cervical cancer alone accounts for more than 604,000 new cases and more than 341,000 deaths. The low-risk types 6 and 11 cause genital warts, with an estimated 15.5 million new cases each year.

Condoms reduce but do not completely prevent HPV transmission, because the virus spreads through contact with skin and mucous membranes in the genital area. HPV does not spread through blood or through sharing food and drink.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 1, questions 1 and 3; Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part III, section 19.1, pp. 140–141.

At what age and how many doses

According to the 2026 Recommendations:

Gardasil 9 (9 types), males and females aged 9–14: 2 doses, 6 or 12 months apart. Dose 2 should be given between 5 and 13 months after dose 1. If dose 2 is given less than 5 months after dose 1, a third dose is needed.
Gardasil 9, males and females aged 15–45: 3 doses at 0, 2 and 6 months, completed within 1 year.
Gardasil (4 types), for females aged 9–26: 2 doses at 9–13 years, 3 doses if older.

The HPV Q&A book was written before the 2026 Recommendations. At that time, it says, the vaccine was not yet indicated in Vietnam for people aged 27–45. Ask your vaccination clinic about the current indications.

No booster is needed after completing the course. Studies have shown protection lasting at least 14 years with the quadrivalent vaccine and at least 8 years with the 9-valent vaccine.

Source: Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part III, section 19.2, pp. 143–144; Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 2, questions 2, 3 and 5.

Why vaccinate from 11–12 years

The vaccine works best when given before the first exposure to HPV. Children aged 9–14 need only 2 doses instead of 3. Many studies show that HPV vaccination does not lead children to start having sex earlier.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 2, question 6.

Do men need the vaccine?

Yes. Men are infected with HPV at a higher rate than women, and this rate does not fall with age. HPV causes genital warts and cancers of the penis, anus and throat in men. HPV-related throat and anal cancers in men are increasing. There is currently no early screening for these cancers in men. Natural HPV infection also does not protect men from being infected again.

Men who have sex with men are at high risk of HPV transmission and are strongly advised to be vaccinated.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 2, questions 7 and 10.

Should people who are sexually active or have had HPV be vaccinated?

Yes. You may have been infected with a few HPV types but not with the other types in the vaccine. The vaccine still helps prevent reinfection and infection with those types. Whether or not someone has had sex does not affect how well the vaccine works.

No HPV test is needed before vaccination. A blood test for HPV antibodies does not show whether someone is currently infected.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 1, question 7; Part 2, questions 4 and 11.

Is cervical cancer screening still needed after vaccination?

Yes. The vaccine does not cover all high-risk HPV types, and cervical cancer has other risk factors too. Vaccinated women should still have gynaecological check-ups and screening as scheduled.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 2, question 9.

What if a dose is late?

There is no need to start again, even after a gap of many years. Get the missing doses as soon as possible, at the intervals set for your age.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 3, question 5.

Finding out you are pregnant after vaccination

The HPV vaccine is contraindicated during pregnancy. However, if pregnancy is discovered after vaccination, the HPV Q&A book advises:

Do not terminate the pregnancy.
Continue routine antenatal care as normal.
Get the remaining doses after the baby is born.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 4, question 1; Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part IV, section 2.4.2, p. 183.

Does the HPV vaccine cause infertility?

No. There is no evidence that the HPV vaccine is linked to infertility in boys or girls. A 2020 World Health Organization report found that the HPV vaccine is not associated with infertility in girls and women.

Source: Questions and answers on HPV vaccines (Vietnam Association of Preventive Medicine in collaboration with MSD Vietnam), Part 4, question 2.