I was sitting in an exam room recently with a young woman I care about when a physician — covering for her regular doctor — began discussing the HPV vaccine. The enthusiasm in the room was genuine. And then came the sentence that stopped me cold.
“The exciting news,” she said, “is that we may not need Pap smears anymore.”
I am a registered nurse. I have worked across oncology, behavioural health, and integrative medicine. I have read the literature on this vaccine carefully and with an open mind. And I left that appointment with the same question I have carried for years about the gap between what the science actually shows and what gets communicated in a ten-minute clinical encounter.
That gap is what this blog is about.
What HPV Is — and What It Isn’t
Human papillomavirus is extraordinarily common. It is estimated that approximately 80% of sexually active people will acquire at least one HPV infection during their lifetime. The vast majority of these infections — in people with healthy immune systems — clear spontaneously within one to two years without intervention, without symptoms, and without consequence.
There are more than 200 known strains of HPV. Of these, approximately 14 are classified as high-risk oncogenic strains. The development of cervical cancer from HPV infection is not rapid or inevitable. It is a process that takes 10 to 20 years from initial infection to invasive cancer — a window that existing screening programmes are specifically designed to intercept. Most women who develop cervical cancer in countries with robust screening infrastructure do so because they were not screened, not because screening failed them.
What the Vaccine Actually Covers
Gardasil 9 — the current formulation marketed by Merck and the version most widely used globally — covers nine HPV strains: types 6, 11, 16, 18, 31, 33, 45, 52, and 58. This is meaningfully broader than the original four-valent Gardasil, and the nine strains covered are responsible for approximately 90% of cervical cancers and 90% of genital warts.
That 90% figure is the one that appears in promotional materials and is repeated in clinical settings. It is accurate, as far as it goes. What it does not tell you is what remains uncovered — and why that matters for the claim that Pap smears may no longer be necessary.
The strains not covered by Gardasil 9 are responsible for the remaining 10% of cervical cancers — a figure that translates to thousands of women globally every year. Those cancers will not be prevented by the vaccine. They will only be caught by screening. Eliminating Pap smears in a vaccinated population does not eliminate cervical cancer risk. It eliminates the surveillance net for the cancers the vaccine does not cover.
There is also the question of women who were already exposed to HPV before vaccination — which, given the vaccine is most effective before sexual debut, includes the majority of adult women alive today. For them, the vaccine offers no therapeutic benefit to existing infections. Pap smear screening remains their primary protection.
The Clinical Trials: What Was Actually Measured
The Surrogate Endpoint Problem. The trials measured reductions in cervical intraepithelial neoplasia grades 2 and 3 (CIN 2/3) — precancerous lesions detected on biopsy. They did not — because the timeframe did not allow it — measure actual cervical cancer incidence or cervical cancer mortality. The assumption that CIN 2/3 reduction translates directly to cancer prevention is biologically reasonable but not proven in the trial data. It is an extrapolation, made more complicated by the fact that CIN 2 lesions regress spontaneously in approximately 40–60% of cases without intervention. Peter Doshi, a senior editor at the British Medical Journal, has written critically about the evidentiary basis for the vaccine’s approval on these grounds.
Japan and Denmark: When Regulatory Caution Followed
Japan suspended its proactive recommendation of the HPV vaccine in 2013 following a cluster of reports of serious adverse events — including complex regional pain syndrome and postural orthostatic tachycardia syndrome (POTS) — in vaccinated girls. The Japanese government did not ban the vaccine; it withdrew the active recommendation pending further investigation. That suspension remained in place for nearly a decade. In 2022, Japan reinstated the recommendation after additional review, but the episode raised questions about post-marketing surveillance adequacy that have not been fully resolved.
Denmark saw the emergence of a significant patient advocacy movement following reports of a syndrome characterised by chronic pain, autonomic dysfunction, fatigue, and fainting in young women following HPV vaccination. The Danish Health Authority and the European Medicines Agency both conducted reviews and ultimately concluded the evidence did not support a causal link. Critics of that conclusion have pointed to methodological limitations in the review process. The debate in the peer-reviewed literature has not fully closed.
Adverse Event Reporting: What Post-Marketing Surveillance Shows
The Vaccine Adverse Event Reporting System (VAERS) — the US passive surveillance database co-managed by the FDA and CDC — has received more reports for Gardasil than for any other vaccine in its history. VAERS is a passive reporting system, and its limitations are well-documented: it captures only a fraction of actual adverse events, it cannot by itself establish causation, and it is subject to reporting bias in both directions. These limitations are real and important. What they do not justify is dismissing VAERS data entirely. The appropriate response to a large and consistent signal in a passive surveillance system is active investigation — the kind of rigorously designed epidemiological studies that could confirm or refute causation. In many areas of HPV vaccine safety, those studies have not been conducted at the scale and independence that the signal warrants.
The Fertility Question: Contested but Worth Raising
In 2018, Gayle DeLong, an economist at Baruch College, published a study in the Journal of Toxicology and Environmental Health reporting an association between HPV vaccination and reduced pregnancy rates in women aged 25–29. The study attracted immediate and significant criticism, including inadequate control for confounding variables, and the finding has not been replicated in a more rigorously designed study. What has also not happened is a large-scale, prospective, independently funded study specifically designed to examine HPV vaccination and subsequent fertility outcomes over the reproductive lifespan. Given the scale of the vaccination programme and the age at which it is administered, the absence of that data is a legitimate gap.
The Pap Smear: A Proven Tool Being Quietly Retired
The Pap smear has one of the most impressive track records in the history of preventive medicine. Since its widespread adoption in the mid-twentieth century, rates of cervical cancer in countries with robust screening programmes have fallen by more than 70%. The longest follow-up data available for Gardasil at the time of writing extends to approximately 12 years. Cervical cancer develops over 10 to 20 years. The question of whether a vaccine administered at age 11 or 12 provides durable protection through the peak risk years of the fourth and fifth decade of life has not been answered by the existing evidence base.
Current guidelines in several countries have already moved to extend Pap smear intervals — from annual to every three to five years in vaccinated women. Some jurisdictions are piloting HPV-only testing as the primary screen. These are policy decisions being made on the basis of modelling studies and short-term efficacy data, not on direct observation of cervical cancer incidence in the first fully vaccinated cohorts — cohorts who are, as of this writing, only beginning to reach the ages at which cervical cancer typically presents. We are, in some sense, running the long-term experiment now. The outcomes will not be fully visible for another decade. The women in that experiment deserve to know they are in it.
What Informed Consent Actually Requires
Informed consent is not a signature on a form. It is a process. It requires that a patient — or a parent making a decision for a child — receive accurate, balanced, and complete information about what a medical intervention is expected to do, what the known risks are, what the unknowns are, and what alternatives exist.
In the case of the HPV vaccine, a complete informed consent conversation would include: what strains are covered and what are not; what the trials actually measured; what adverse events have been reported; what is not yet known about long-term durability and fertility outcomes; and what alternatives exist, including continuation of regular Pap smear and HPV co-testing.
And one more — the conversation that somehow disappeared from the exam room entirely: what about delaying sexual activity? I say this not as a moral position but as a clinical one. HPV is sexually transmitted. The most effective way to reduce exposure to any sexually transmitted infection is a frank, age-appropriate conversation about choices, readiness, and consequences. I have sat in appointments with my own daughter and that subject has never once come up — not once — while a vaccine was offered with considerable enthusiasm. A pharmaceutical intervention and an honest conversation are not mutually exclusive. One of them costs nothing, carries no side effects, and has been quietly retired from the clinical encounter without most parents even realising it was gone.
This is not a ten-minute conversation. It is the conversation that patients and parents deserve. And the fact that it is not happening consistently is not a failure of individual clinicians — many of whom are doing their best within a system that does not allocate time for it. It is a failure of the informed consent infrastructure around a vaccination programme that has been marketed with a confidence that outpaces its evidence base.
Questions Worth Bringing to Your Next Appointment
Which strains does this vaccine cover, and which cervical cancer cases would it not prevent? What screening will I or my child still need after vaccination, and for how long? What were the clinical trials actually designed to measure — cancer prevention directly, or a surrogate marker? What is the follow-up data over ten or more years? What adverse events are listed on the package insert, and what has post-marketing surveillance shown? What do we know — and what do we not yet know — about the long-term durability of protection, and is there discussion of booster requirements?