P-3. Assessing the Public Health Impact of Transitioning from a 4-valent to a 9-valent HPV Vaccination Program in Panama
Authors: Carlos Orengo Juan , Marisol Rendon Ana , Cristina Lima Bruna , Daniels Vincent , Saxena Kunal , Pavelyev Andrew , Parellada Cintia I 
Published: January 2025

Abstract

Background
In 2008, a human papillomavirus (HPV) vaccine was introduced for 10-year-old girls in the National Immunization Program in Panama, switching to a quadrivalent HPV gender-neutral vaccination (4vHPV GNV). This analysis aimed to estimate the expected public health and economic impact of switching from a 4vHPV GNV to 9vHPV GNV in Panama.Table 1.Main parameters used in the model

Methods
A previously published dynamic model of HPV disease transmission was calibrated to simulate the natural history of HPV and attributable disease burden in Panama. The model assumed a two-dose schedule over a 100-year time horizon, lifetime immunity after vaccination, continuous cytology screening, and herd immunity. The outcomes measured were incremental averted cases and deaths of cervical, vaginal, vulvar, anal, penile, head/neck HPV-attributable cancers, recurrent respiratory papillomatosis, genital warts, and cervical intraepithelial neoplasia (CIN) 1 and 2/3. Panama specific data were used for calibration (Table 1).Table 2.Additional avoided cases/cumulative percent reduction and deaths/mortality percnt reduction of HPV-attributable diseases and cancers with 9v-HPV relative to 4v-HPV strategy over 100 years in Panama

Results
After 100 years, the 9vHPV GNV scenario is estimated to provide faster and greater reductions in the incidence and mortality of HPV 6/11/16/18/31/33/45/52/58-attributable diseases and cancers compared to the 4vHPV GNV. The fastest and greatest cumulative reduction compared to 4vHPV GNV were observed in cervical cancer, CIN 1, and CIN 2/3, totaling 46,760 averted cases and 1,760 deaths (Table 2 and Fig.1). The other cancers also exhibited a reduction in cumulative incidence compared to 4VHPV GNV at year 100, albeit at a later stage than cervical cancer (Fig. 2).Figure 1.Estimated reductions in incidence and mortality of cervical cancer and cervical intraepthelial neoplasia attributable to HPV 6/11/16/18/31/33/45/52/58 over 100 years in Panama

Conclusion
In Panama, switching from 4vHPV GNV to 9vHPV GNV is projected to provide a substantial public health impact in terms of reduction of HPV-attributable disease and cancers due to HPV 6/11/16/18/31/33/45/52/58 in both genders compared to the current strategy. Faster and greater reductions in the incidence and mortality of cervical cancer and its precursors were seen compared to anal, penile, and head/neck cancers, which typically peak in the sixth decade of life versus fourth decade in cervical cancer, reflecting the natural history of HPV infection in different anatomical sites.Figure 2.Estimated reductions in incidence and mortality of anal cancer attributable to HPV6/11/16/18/31/33/45/52/58 over 100 years in Paranama

Disclosures
Juan Carlos Orengo, MD, MPH, PhD, Merck & Co., Inc: Employee|Merck & Co., Inc: Stocks/Bonds (Private Company) Ana Marisol Rendon, MD, MS, Merck & Co., Inc: Employee|Merck & Co., Inc: Stocks/Bonds (Private Company) Bruna Cristina Lima, n/a, Merck & Co., Inc: Employee Vincent Daniels, PhD, Merck & Co., Inc: Employee|Merck & Co., Inc: Stocks/Bonds (Private Company) Kunal Saxena, PhD, Merck & Co., Inc: Stocks/Bonds (Private Company) Andrew Pavelyev, n/a, HCL America, Inc.: emplo Cintia I. Parellada, MD, PhD, Merck & Co., Inc: Employee|Merck & Co., Inc: Stocks/Bonds (Private Company)