Introduction of a national human papillomavirus vaccination program in Australia has been associated with declines in the incidence of juvenile-onset recurrent respiratory papillomatosis, according to a nationwide study.

Juvenile-onset recurrent respiratory papillomatosis (JORRP) is a rare condition characterized by recurring growths in the larynx that often require multiple operations to remove. The disease typically emerges around age 3-4 years and most cases are thought to be caused by human papillomavirus (HPV) subtypes 6 and 11, which are acquired from the mother during birth.

In this prospective study using data from the Australian Paediatric Surveillance Unit, researchers examined the incidence of juvenile-onset recurrent respiratory papillomatosis from October 2011 to December 2015, set against the background of the introduction of Australia’s national HPV vaccination program between 2007 and 2009 (J Infect Dis. 2017 Nov 9. doi: 10.1093/infdis/jix498).

Overall, just 15 cases were reported during the course of the study; 7 in the 1st year, 3 in the 2nd year, 2 each in the 3rd and 4th years, and 1 case in the last year. The annual rates declined from 0.16 per 100,000 children aged 0-14 years in 2012 to 0.02 per 100,000 in 2016.

Of the cases identified, none of the mothers had been vaccinated against HPV before pregnancy and 20% had a history of genital warts. Seven cases were genotyped; 4 were HPV-6 and 3 were HPV-11, and 13 of the 15 cases were born vaginally.

“Our data strongly suggest that the previously documented impact of quadrivalent HPV vaccination in dramatically reducing the prevalence of HPV-6 and HPV-11 genital infection in the Australian population is translating to a reduction in the risk of transmission to infants intrapartum and subsequent development in some of these children of JORRP,” wrote Daniel Novakovic, MD , of the University of Sydney Medical School, and his coinvestigators.

The authors noted that their initial estimate of infection rates was lower than that seen in other studies, such as the 0.5 per 100,000 rate seen in private health insurance data, and the 1.0 per 100,000 seen with Medicaid data in the United States.

Given that the study period started nearly 5 years after the vaccination program began, they suggested that this lower prevalence may reflect the early impact of the vaccine, particularly given that the prevalence of genital warts had already dramatically declined by that point.

However they also stressed that their study relied on clinicians actively reporting cases, and that given surveillance only began after the introduction of the vaccination program, no data were available on the incidence before that point.

The study was supported by a research grant from Merck and by the Australian Paediatric Surveillance Unit, which is supported by the Australian Government Department of Health. Three authors declared research funding from Merck/Seqirus for HPV studies. Two authors declared funding, speaking fees, and other support from a range of pharmaceutical companies. No other conflicts of interest were declared.