Research suggests potential global public health benefits from HPV vaccine

Preliminary research by a collaborative team of researchers from Victoria University of Wellington, the University of Otago and the University of Auckland suggests the Human papillomavirus (HPV) vaccine may play a role in reducing pre-term births.

The study builds on evidence to date suggesting that infection with HPV in pregnancy may be a factor in pre-term births, defined as delivering before 37 weeks of pregnancy. If this is the case, then receiving the preventative HPV vaccine could potentially reduce pre-term births.

Co-led by Professor Bev Lawton of Victoria’s Centre for Women’s Health Research Te Tātai Hauora o Hine, the research team linked records in the New Zealand national immunisation database with other national data to investigate whether having previously received the HPV vaccine had an impact on adverse pregnancy outcomes.

The research found that receiving more than one vaccine dose prior to pregnancy was associated with a 13 percent reduced likelihood of having a pre-term birth. “The potential public health impact of even a small reduction in the overall burden of morbidity from pre-term birth is considerable,” says Professor Lawton, co-principal investigator on the project with Dr Noelyn Hung of the University of Otago.

Professor Lawton says an estimated 14.9 million infants are born prematurely worldwide. “Based on this estimate, if half of all pregnant women globally received the HPV vaccination before their pregnancy, a potential 10 percent reduction in pre-term birth would equate to a reduction of 745,000 pre-term births annually, with associated reductions in mortality and long term morbidity.”

The study took into account differences between vaccinated and unvaccinated women based on geographical region, maternal age at delivery, ethnicity, Body Mass Index and socio-economic status. It drew on data from almost 35,000 pregnancies. Of those women, 62.3 percent were unvaccinated and 27.7 percent were fully vaccinated with Gardasil®, meaning they had received all three doses.

NZ introduced an HPV vaccination programme in 2008 for young women from the age of 12 years with a catch up for those up to 26 years of age. In 2017 this was broadened to include young men of the same age as well, with the information on vaccinations held in the New Zealand National Immunisation database

Professor Lawton cautions that it is a retrospective cohort study and it is not possible to draw definitive conclusions about causality. “It looks really exciting but these initial findings will need to inform further research. The research team has joined with researchers in Australia and Sweden in a grant application to collect further evidence of the potential link with HPV vaccination and better pregnancy outcomes. ”

This study is the first in the world to suggest an effect of prior vaccination on pregnancy outcomes. Any vaccine that is shown to improve important pregnancy outcomes is expected to be of significant global importance.

The research, just published in Vaccine journal and available here, is authored by Dr Lawton (Victoria University), Anna Howe, Nikki Turner (University of Auckland), Sara Filoche,Tania Slatter, Celia Devenish and Noelyn Hung (University of Otago).The study began in 2016 when the women’s health research centre was hosted at the University of Otago.