Louiza S. Velentzis

The impact of HPV vaccination beyond cancer prevention: effect on pregnancy outcomes

While the benefits of human papillomavirus (HPV) vaccination relating to cervical cancer prevention have been widely documented, recent published evidence is suggestive of an impact on adverse pregnancy outcomes (APOs) in vaccinated mothers and their infants, including a reduction in rates of preterm births and small for gestational age infants. In this review, we examine this evidence and the possible mechanisms by which HPV vaccination may prevent these APOs. Large-scale studies linking HPV vaccination status with birth registries are needed to confirm these results. Potential confounding factors to consider in future analyses include other risk factors for APOs, and historical changes in both the management of cervical precancerous lesions and prevention of APOs. If confirmed, these additional benefits of HPV vaccination in reducing APO rates will be of global significance, due to the substantial health, social and economic costs associated with APOs, strengthening the case for worldwide HPV immunization.

A modelled analysis of the impact of COVID-19-related disruptions to HPV vaccination

COVID-19 disrupted school attendance in many countries, delaying routine adolescent vaccination against human papillomavirus (HPV) in some settings. We used Policy1-Cervix , a dynamic model simulating HPV transmission, natural history, vaccination, cervical screening, and diagnosis of HPV-related cancers, to estimate the impact on HPV-related cancers from disruptions to HPV vaccination in a high-income setting. A baseline scenario of no disruption to HPV vaccination was modelled, which assumed uptake of the nonavalent vaccine at the age of 12 by 82.4% of females and 75.5% of males, as is the coverage in Australia. Additional lifetime HPV-related cancer cases were calculated for three disruption scenarios affecting one birth cohort (2008; aged 12 in 2020) compared to the baseline scenario: (1) 1-year delay (no doses missed); (2) 1- to 7-year delay (slow catch-up); (3) no catch-up (herd effects only). A fourth scenario assumed no catch-up HPV vaccination for two birth cohorts, that is all individuals born in 2008 and in 2009 missed vaccination (worst-case scenario). Compared to 1532 HPV-related cancer cases estimated for the baseline no disruption scenario, we found a 1-year delay could result in ≤0.3% more HPV-related cancers ( n = 4) but the increase would be greater if catch-up was slower (5%; n = 70), and especially if there was no catch-up (49%; n = 750). Additional cancers for a single missed cohort were most commonly cervical (23% of the additional cases) and anal cancers (16%) in females and oropharyngeal cancers in males (20%). In the worst-case scenario of two birth cohorts missing vaccination, ≤62% more HPV-related cancers would be diagnosed ( n = 1892). In conclusion, providing catch-up of missed HPV vaccines is conducted, short-term delays in vaccinating adolescents are unlikely to have substantial long-term effects on cancer.

Participation in the National Cervical Screening Program Among Women Who Gave Birth in New South Wales, Australia by Place of Maternal Birth: A Data Linkage Analysis

ABSTRACT Objective High participation rates in the National Cervical Screening Program (NCSP) by all groups of women are required to ensure the equitable elimination of cervical cancer in Australia. In this study, we examine screening participation of overseas‐born women compared to Australian‐born women who gave birth. Design Population‐based retrospective cohort study using linked health datasets. Setting and Participants Women who gave birth in New South Wales between January 1, 2000 and June 30, 2017. Main Outcome Measures Participation in the NCSP (≥ 1 cytology test) in the 3‐ and 5‐year periods prior to delivery by place of maternal birth, adjusted for multiple socio‐demographic and health characteristics. Results Among the 1 332 669 mothers who gave birth over the study period, overall cervical screening participation in the 3‐ and 5‐year periods prior to delivery was 67.0% and 75.7%, respectively. Participation was lower for overseas‐born mothers compared to Australian‐born mothers for both the 3‐year (57.8% vs. 71.7%; adjusted odds ratio [aOR]: 0.51, 95% confidence interval [CI]: 0.50–0.51) and 5‐year (64.9% vs. 81.2%; aOR: 0.40, 95% CI: 0.40–0.40) participation periods. All groups of overseas‐born women had substantially lower screening participation compared to Australian‐born women, with the lowest relative 3‐year participation in mothers born in Southern/Central Asia (aOR: 0.30, 95% CI: 0.30–0.31), Oceania (aOR: 0.31, 95% CI: 0.30–0.32), North‐East Asia (aOR: 0.49, 95% CI: 0.48–0.50), and New Zealand (aOR: 0.49, 95% CI: 0.48–0.51). Conclusions Overseas‐born women had around half the cervical screening participation in the period prior to birth compared to Australian‐born women. It is likely that opportunities to screen these under‐screened groups during the antenatal period, typically a time of repeated health services contact, are missed.