Human Papillomavirus (HPV) and Cervical Cancer

Human Papillomavirus (HPV) is a very common virus that spreads through close skin-to-skin and sexual contact. Most people get it at some point in life, and the body usually clears it on its own within a year or two. But a few types of HPV can stay in the body for many years and slowly turn normal cells into cancer cells.

The most common cancer caused this way is cervical cancer, the cancer of the cervix (the lower, narrow part of the womb). It is almost fully preventable with a vaccine and regular screening.

Why does this matter so much?

Cervical cancer kills a large number of women in their most productive years. Yet it is one of the few cancers that can almost be wiped out, because we know its cause (HPV), we have vaccines, and simple tests can catch it early. That is why the WHO has set a global goal to eliminate it.

How does HPV cause cancer?

There are about 200 types of HPV. They are grouped by risk:

• Low-risk types (such as 6 and 11): cause genital warts (small growths on the skin), but almost never cancer. Types 6 and 11 cause about 90% of genital warts.
• High-risk types (such as 16 and 18): can cause cancer. The WHO says at least 14 types are cancer-causing. Types 16 and 18 together cause about 70% of cervical cancers.

The process is slow. If a high-risk infection does not clear, it can cause changes in cervical cells called precancerous lesions. Over time these can turn into cancer. In women with a normal immune system this usually takes 15 to 20 years. In women with a weak immune system, such as those with untreated HIV, it can take only 5 to 10 years. This long gap is a big opportunity: screening can catch the changes and treat them before cancer appears.

HPV does not only affect women. It can also cause cancers of the anus, penis, mouth and throat, as well as vulvar and vaginal cancers. This is why many countries now vaccinate boys too.

How do HPV vaccines work?

HPV vaccines do not contain the live virus. They are made of virus-like particles (VLPs). Scientists take the gene for the main outer protein of HPV, called L1, and put it into yeast or other cells. These cells make the L1 protein, which assembles itself into empty shells that look like the virus from outside but have no genetic material inside.

So they cannot cause infection. Think of it as showing the body a photograph of a thief: the body learns to recognise the thief without the thief ever entering. When real HPV comes later, the antibodies are ready to block it. The vaccine works best if given before a person is ever exposed to HPV, which is why it is given at ages 9 to 14.

What types of HPV vaccines exist?

Vaccines are named by how many HPV types they cover:

• Bivalent (2 types: 16, 18): Cervarix (GSK), Cecolin (Innovax, China), Walrinvax (China).
• Quadrivalent (4 types: 6, 11, 16, 18): Gardasil (Merck, first approved in 2006) and Cervavac (Serum Institute of India).
• Nonavalent (9 types: 6, 11, 16, 18, 31, 33, 45, 52, 58): Gardasil 9 (Merck).

How many doses are needed?

In April 2022, the WHO's Strategic Advisory Group of Experts on Immunization (SAGE) said that a single dose gives protection similar to two doses for girls and young women aged 9 to 20. The WHO confirmed this in its December 2022 position paper. A single-dose schedule makes vaccination cheaper and easier, and stretches limited vaccine supply.

Each vaccine's approved schedule can still differ. Cervavac's label, for example, uses two doses (at 0 and 6 months) for ages 9 to 14, and three doses (at 0, 2 and 6 months) for ages 15 to 26.

What is the WHO's elimination plan?

In November 2020, the WHO launched the Global Strategy to Accelerate the Elimination of Cervical Cancer. "Elimination" means bringing new cases below 4 per 100,000 women per year. To get there, every country should reach the 90-70-90 targets by 2030:

• 90% of girls fully vaccinated with the HPV vaccine by age 15.
• 70% of women screened with a high-performance test by age 35, and again by age 45.
• 90% of women found with pre-cancer or cancer receive treatment.

What is India's situation?

India carries one of the largest burdens of cervical cancer in the world. As per WHO's GLOBOCAN 2022 estimates:

• About 1.27 lakh new cases and about 80,000 deaths in India in 2022.
• It is the second most common cancer among Indian women, after breast cancer.
• India records more cervical cancer deaths than any other country.

How is India responding?

• Sikkim (2018) became the first state to run a statewide HPV vaccination campaign, for girls aged 9 to 13 through schools.
• Cervavac got marketing authorisation from the Drugs Controller General of India (DCGI) on 12 July 2022 and was launched on 1 September 2022. It was developed with DBT and BIRAC. It is approved for both girls and boys aged 9 to 26.
• In October 2026, the WHO gave Cervavac prequalification. This means the WHO found it meets global standards of quality, safety and effectiveness. UN agencies such as UNICEF can now buy it for other countries. It does not by itself put Cervavac into any country's national programme; each country still decides that.
• The Interim Union Budget of February 2024 announced that the government would encourage HPV vaccination for girls aged 9 to 14.
• On 28 February 2026, India launched a nationwide HPV vaccination campaign from Ajmer, Rajasthan. It offers a free single dose of Gardasil-4 (Merck's quadrivalent vaccine) to girls aged 14 (about 1.15 crore girls). Vaccination is voluntary and needs parental consent, and is given at Ayushman Arogya Mandirs, community health centres, district hospitals and medical colleges.
• Screening: Under the national programme for non-communicable diseases, women aged 30 to 65 are screened for common cancers, including cervical cancer, often using VIA (Visual Inspection with Acetic Acid), a cheap test where a health worker applies dilute vinegar to the cervix and looks for white patches.

Commonly confused concepts

• HPV vs HIV: HPV (Human Papillomavirus) causes warts and some cancers. HIV (Human Immunodeficiency Virus) weakens the immune system and causes AIDS. They are different viruses, though HIV makes HPV-related cancer develop faster.
• HPV vs Herpes (HSV): Both spread through close contact, but herpes causes painful sores and does not cause cervical cancer.
• Bivalent vs quadrivalent vs nonavalent: The number tells how many HPV types the vaccine covers: 2, 4 or 9. Only vaccines that cover types 6 and 11 (quadrivalent and nonavalent) also protect against genital warts.
• Preventive vs therapeutic vaccine: HPV vaccines prevent new infection. They do not cure an existing infection or cancer. That is why screening is still needed for adult women.
• Pap smear vs HPV DNA test vs VIA: A Pap smear looks at cervical cells under a microscope. An HPV DNA test checks for high-risk HPV itself and is the WHO's preferred test. VIA is a quick visual test needing no lab.

Issues, criticism and the way forward

• Vaccine hesitancy: Some parents worry about safety or feel uneasy because the virus spreads sexually. Clear public communication through schools and health workers is needed. Large studies across many countries have found the vaccines safe.
• Low screening: Only a small share of Indian women have ever been screened. Experts suggest wider use of HPV self-sampling and point-of-care tests.
• Cost and supply: Imported vaccines are costly, and global supply has been tight. Local production (Cervavac) and single-dose schedules help.
• Boys and older age groups: The national campaign covers 14-year-old girls only. Some experts argue for adding 9 to 13-year-olds and boys over time; others prioritise reaching full coverage of girls first.
• Treatment access: Many women are diagnosed late, when treatment is harder. Strengthening district-level cancer care is part of the way forward.

Concepts to Know

• Cervix: The narrow lower part of the uterus (womb) that opens into the vagina.
• Precancerous lesion: A patch of abnormal cells that is not cancer yet but may become cancer if left untreated.
• Antibody: A protein the immune system makes to recognise and block a specific germ.
• Virus-like particle (VLP): An empty shell made of a virus's outer protein. It trains the immune system but cannot cause infection because it has no genetic material.
• Valency (bivalent, quadrivalent, nonavalent): The number of virus types a vaccine protects against.
• GLOBOCAN: A database of cancer cases and deaths for every country, run by WHO's International Agency for Research on Cancer (IARC).
• WHO prequalification: A WHO check that a vaccine or medicine meets global standards. UN agencies like UNICEF buy only prequalified vaccines for poorer countries, so it opens a global market.