As India debates the rollout of a school-based HPV vaccination programme, fresh evidence from Sweden adds weight to the public health case. New data shows that high vaccination coverage not only protects those who receive the vaccine, but also significantly reduces the risk of cervical precancerous lesions among unvaccinated women. For a country where cervical cancer remains a major killer, the findings sharpen the policy question from whether to vaccinate, to how quickly and how widely.
Why the Swedish evidence matters
Cervical cancer is the second most common cancer among Indian women, affecting around 1.25 lakh women and causing nearly 75,000 deaths annually. While the effectiveness of HPV vaccines in preventing infection is well established, the Swedish study is notable for demonstrating a clear “herd-protective” effect — a reduction in disease risk even among those who were never vaccinated.
Such real-world evidence is especially relevant for India, where achieving universal adult vaccination is unrealistic, but school-based programmes offer a scalable pathway to population-level protection.
What the study examined
Researchers in Sweden analysed the incidence of high-grade cervical precancerous lesions among unvaccinated women born between 1989 and 2000, divided into four cohorts based on vaccine availability and coverage:
- Women born between 1989–92, when vaccination was subsidised but uptake was limited (around 25%).
- Those born between 1993–98, eligible for catch-up vaccination, with coverage rising to about 55%.
- Women born in 1999–2000, who grew up under a school-based vaccination programme achieving nearly 80% coverage.
The focus was not on vaccinated women, but on those who remained unvaccinated within these cohorts.
Clear evidence of herd protection
The results showed a striking decline in precancerous lesions among unvaccinated women as vaccination coverage increased in the broader population. Incidence rates fell from 1.17 per 1,000 person-years in the earliest cohort to 0.54 in the cohort exposed to school-based vaccination.
Unvaccinated women born in 1999–2000 — surrounded by peers who were largely vaccinated — had about half the risk of developing serious cervical precancerous changes compared to unvaccinated women born a decade earlier. Researchers described this as a “real-world evaluation of herd effect”.
What experts say about relevance for India
According to , while India does not yet have sufficient vaccination coverage to generate its own herd immunity data, international experience consistently points in the same direction. Australia, for instance, saw sharp declines in genital warts among both women and men following HPV vaccination. In the UK, precancerous cervical lesions have nearly disappeared in vaccinated cohorts.
These experiences suggest that indirect protection is not theoretical, but achievable with sustained high coverage.
Implications for India’s vaccination strategy
India plans to vaccinate girls aged nine to 14 years through school-based programmes, followed by inclusion in routine immunisation. This age window is crucial because the vaccine is most effective before sexual debut, with efficacy declining as age increases.
Public health experts emphasise that coverage levels matter. While 90% coverage would be ideal, even achieving 70% could generate substantial population-wide benefits, protecting girls who are missed by the programme as well.
Beyond cancer: easing the health system burden
A less discussed benefit of widespread HPV vaccination is the reduction in diagnostic and follow-up burdens. As HPV infections decline, fewer women will test positive on screening methods such as Pap smears or HPV tests, reducing the need for biopsies and further invasive procedures.
Given that more than 95% of cervical cancers are linked to persistent infection with high-risk HPV strains — particularly types 16 and 18, which cause about 70% of cases globally — prevention at source offers long-term system-wide gains.
Vaccines, strains, and broader protection
Quadrivalent vaccines currently available in India, including those manufactured domestically, protect against HPV types 16 and 18, as well as types 6 and 11, which cause genital warts. By preventing infection early, vaccination reduces not only cervical cancer risk, but also cancers of the anus, vagina, and oropharynx associated with HPV.
What to note for Prelims?
- HPV as the primary cause of cervical cancer.
- Concept of herd immunity in vaccination programmes.
- Target age group for HPV vaccination.
- High-risk HPV types (16 and 18).
What to note for Mains?
- Public health rationale for school-based vaccination programmes.
- Cost-effectiveness and herd protection in preventive healthcare.
- Challenges in achieving high vaccination coverage in India.
- Role of vaccination in reducing long-term health system costs.
