Why Sweden’s HPV Vaccine Findings Matter for India’s Fight Against Cervical Cancer

As India weighs a nationwide, school-based HPV vaccination programme, fresh evidence from Sweden adds urgency — and optimism — to the debate. A large population-based study has shown that high HPV vaccine coverage not only protects vaccinated girls, but also significantly lowers the risk of precancerous cervical lesions among unvaccinated women through a clear herd-protective effect. For a country where cervical cancer remains the second most common cancer among women, this finding carries major public health implications.

What the Swedish study shows — herd protection in real life

The Swedish study tracked unvaccinated women across four birth cohorts between 1989 and 2000, examining the incidence of high-grade precancerous cervical lesions — a well-recognised precursor to cervical cancer.

The results revealed a striking pattern. Women born in 1999–2000, who grew up alongside peers vaccinated through a school-based programme with nearly 80% coverage, had about half the risk of developing serious precancerous cervical changes compared with unvaccinated women born in the mid-1980s, when vaccine uptake was low and voluntary.

Incidence rates declined steadily as vaccination coverage rose — from 1.17 per 1,000 person-years in the earliest cohort to just 0.54 in the school-vaccinated cohort. Researchers described this as a clear “real-world evaluation of herd effect”, demonstrating that high coverage can protect entire populations, not just individuals who receive the vaccine.

Why this is crucial for India

For India, the findings are especially relevant. Cervical cancer affects around 1.25 lakh women annually and claims nearly 75,000 lives each year, making it one of the country’s deadliest yet most preventable cancers.

India has so far lacked large-scale data on herd immunity because HPV vaccination coverage remains limited. However, experts say the biological principle is well established. As “Neerja Bhatla”, Professor and Head of Obstetrics and Gynaecology, explains, countries like Australia and the UK have already demonstrated dramatic population-level benefits — including sharp declines in genital warts and near-elimination of precancerous lesions in vaccinated cohorts.

Why school-based vaccination makes the difference

The Swedish experience underscores the importance of how vaccination is delivered. Opportunistic or self-paid vaccination achieved only modest coverage. In contrast, school-based programmes ensured high uptake, which proved critical for generating herd protection.

India’s proposed strategy — vaccinating girls aged 9–14 years through schools, followed by integration into routine immunisation — mirrors this model. This age group is crucial because the vaccine is most effective when administered before sexual debut. Efficacy declines as age increases, underscoring the need for early and widespread coverage.

How much coverage is enough?

Public health experts stress that scale matters. Ideally, vaccination coverage should reach around 90% to maximise population protection, though even 70% coverage can yield substantial benefits. High uptake not only protects vaccinated girls but also indirectly shields others by reducing the circulation of high-risk HPV strains.

This population-level protection is particularly valuable in settings like India, where access to regular screening and follow-up diagnostics remains uneven.

Beyond cancer prevention: easing the burden on health systems

One less discussed but critical benefit of widespread HPV vaccination is the reduction in downstream testing. As HPV infections decline, fewer women test positive on screening tools such as Pap smears, HPV tests, or visual inspection with acetic acid.

This means fewer biopsies, fewer confirmatory tests for cervical intraepithelial neoplasia (CIN), and less strain on already stretched health systems. Over time, vaccination reshapes not just disease burden, but the entire prevention and screening ecosystem.

What the vaccine targets — and why timing matters

More than 95% of cervical cancers are caused by persistent infection with high-risk HPV strains. Among at least 14 cancer-causing types, HPV 16 and 18 account for about 70% of cases globally.

The quadrivalent vaccines currently available in India — including those manufactured by “Serum Institute of India” — protect against HPV 16 and 18, as well as HPV 6 and 11, which cause most genital warts. By preventing infection in the first place, these vaccines break the chain that eventually leads to cancer.

Wider gains beyond cervical cancer

HPV infection is also linked to cancers of the anus, vagina, and oropharynx. As vaccination coverage increases, experts expect declines in these cancers as well, amplifying the public health payoff.

The road ahead for India

The Swedish findings strengthen the case for India to move decisively towards a school-based HPV vaccination programme. The benefits will not be immediate — reductions in genital warts appear first, while cancer incidence takes longer to fall — but the long-term gains are substantial and well proven.

For a country where cervical cancer remains a leading killer despite being preventable, the message is clear: high vaccination coverage does not just protect individuals, it transforms population health. The challenge now lies in execution — reaching scale, sustaining trust, and ensuring that prevention finally outpaces disease.