medwireNews: US researchers have found evidence to support catch-up vaccination against the human papillomavirus (HPV) in women given their first dose in older adolescence.
Catch-up quadrivalent HPV vaccination using three doses appeared effective at preventing cervical intraepithelial neoplasia (CIN) of grade two and above (2+) and grade three and above (3+) in girls and women aged 14 to 20 years at their first vaccine dose, according to a large case–control study.
One or more HPV vaccine doses were associated with an 18% reduction in the risk for CIN2+ and a 23% reduction in the risk for CIN3+, compared with no prior vaccination, when the team compared 4357 incident CIN2+ cases and 21773 control individuals, of whom 1849 were incident CIN3+ patients with 9242 matched controls. All the participants were enrolled in the Kaiser Permanente Northern California integrated healthcare delivery system.
The strongest protection against CIN2+ was observed in women who had at least three vaccine doses and received their first dose aged 14–17 years or aged 18–20 years, with respective rate ratios (RRs) of 0.52 and 0.65.
The protection against CIN3+ was even greater for these groups of women, with corresponding RRs of 0.27 and 0.59.
“These results support existing guidelines recommending the full three-dose series for girls and women who start the series after their 15th birthday,” the researchers led by Michael Silverberg (Kaiser Permanente, Oakland, California) report in The Lancet Child and Adolescent Health.
There was no significant protection for women who initiated vaccination at the age of 21 to 26 years, but the researchers say this finding should be confirmed in other settings, particularly those using the newer nonavalent HPV vaccine rather than the quadrivalent one primarily used in the current study.
In an accompanying commentary, Sarah Dilley and Warner Huh, both from the University of Alabama at Birmingham, USA, maintain: “Efforts towards increasing HPV vaccine uptake should be focused on younger adolescents—with a priority on vaccinating children aged 11–12 years and providing catch-up dosing for older adolescents.
“However, in the setting of low rates of HPV vaccination in the USA, the importance of catch-up dosing in young women should not be ignored.
“Given that efficacy studies have shown benefits for catch-up vaccination up to at least age 26 years, more data is needed before abandoning this practice.”
By Anita Chakraverty
medwireNews is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group
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