Angela Ulrich, PhD, MPH, on new safety data for HPV vaccination

A comprehensive meta-analysis from the Vaccine Integrity Project has reaffirmed that human papillomavirus (HPV) vaccines are highly effective in preventing cervical cancer and persistent infections, with no credible links to serious adverse events or adverse pregnancy outcomes.^1,2

After screening more than 5000 abstracts and evaluating 120 studies published between 2024 and 2026, researchers integrated over 20 years of data to provide an updated safety and efficacy profile. The review found that vaccination significantly reduces the risk of high-grade cervical lesions and invasive cancer, which is particularly vital as HPV is responsible for approximately 39300 cancer cases annually in the United States.

A pivotal finding of the analysis involves the potential for a single-dose vaccination schedule. Pooled evidence suggests that one dose may provide protection comparable to two- or three-dose regimens for persistent infection and cervical pre-cancers in females for at least 5 years. While additional doses produce higher antibody levels, a single dose was shown to generate a durable immune response. Transitioning to a reduced-dose schedule could significantly improve global vaccination coverage and address the 9 billion dollar annual burden of HPV-related disease in the United States.

Click here for more on the HPV vaccination safety comprehensive review.

To further explore how these findings might shift clinical guidelines and the long-term durability of a single-dose approach, Contemporary OB/GYN spoke with Angela Ulrich, PhD, MPH, research director of the Center for Infectious Disease Research (CIDRAP) and Policy Research, who led the evidence review.

Angela Ulrich, PhD, MPH, on new HPV safety data

Contemporary OB/GYN:

What does this review reinforce about safety regarding the HPV vaccine, and how should ob-gyns and other women’s health clinicians interpret this review data?

Angela Ulrich, PhD, MPH:

The safety data are reassuring and tell us that the benefits from preventing persistent HPV infection and cancers far outweigh potential risks. Across 25 newly published studies evaluating safety outcomes, there was no credible evidence of increased risk of serious adverse events.

This reinforces the track record of safety seen across over 25 years of monitoring. We evaluated studies that reported on adverse pregnancy outcomes, Guillain-Barré syndrome, chronic fatigue syndrome/myalgic encephalomyelitis, complex regional pain syndrome, infertility, premature ovarian failure, or paralysis associated with HPV vaccination.

In these studies, serious adverse events were rare and generally occurred at similar rates among vaccinated and comparator groups.

Contemporary OB/GYN:

While acknowledging more data are needed, what should clinicians know about a one-dose regimen related to efficacy and ease of vaccination vs multi-dose regimens? What research would you like to see conducted further?

Ulrich:

Evidence comparing one-dose and multi-dose schedules was increasingly supportive of reduced-dose strategies. Randomized trials found no meaningful differences between 1- and 2-dose schedules for serious adverse events, pregnancy outcomes, or persistent HPV16/18 infection through five years of follow-up. Meta-analyses of cohort studies similarly found comparable protection against CIN2+ and CIN3+ among individuals receiving one, two, or three doses.

These findings suggest that a single dose may provide similar clinical protection for key outcomes in females; this may also be true for males, although evidence for long-term durability for males and non-cervical disease endpoints remains more limited.
Contemporary OB/GYN:

As questions about vaccines continue to make their way to clinicians from patients, how important are timely reviews and continued calls for more research to reassure patients?

Ulrich:

The federal government maintained an ongoing and continuous process for reviewing the safety and effectiveness of vaccines, but last year, that process broke down. It no longer functions.

The Vaccine Integrity Project was established to ensure that transparent, independent analyses of vaccines continue so that Americans can have peace of mind that scientific experts are evaluating vital tools that we count on to protect us from infectious diseases. Without that, clinicians would be forced to rely on dated data or federal guidance that, in many cases, is unsupported by evidence.

References:

1. Fitch J. Systematic review reaffirms HPV vaccine safety, supports single-dose regimen potential. Contemporary OB/GYN. Published May 5, 2026. Accessed May 7, 2026.
2. The Vaccine Integrity Project. New Evidence Review Affirms Strong Safety and Effectiveness of HPV Vaccines. University of Minnesota. News release. Published May 5, 2026. Accessed May 7, 2026. https://vaxintegrity.cidrap.umn.edu/new-evidence-review-affirms-strong-safety-and-effectiveness-hpv-vaccines