Indian study highlights
Partha Basu, MD, PhD, of the International Agency for Research on Cancer (IARC) in Lyon, France, and colleagues compared vaccine efficacy of a single dose of Gardasil (HPV 9-valent vaccine, recombinant) to that of two and three doses in protecting against persistent HPV 16 and HPV 18 infection at 10 years postvaccination.
According to the protocol, the plan was to recruit 20,000 unmarried girls, aged 10-18 years, from across India. Recruitment was initiated in September 2009. However, in response to seven unexplained deaths reported in another ongoing HPV vaccination demonstration program in the country, the Indian government issued a notification in April 2010 to stop further recruitment and HPV vaccination in all clinical trials. At this point, Dr. Basu and his team had recruited 17,729 eligible girls.
After suspension of recruitment and vaccination, their randomized trial was converted to a longitudinal, prospective, cohort study by default.
Vaccinated participants were followed up over a median duration of 9 years. In all, 4,348 participants had three doses, 4,980 had two doses (at 0 and 6 months), and 4,949 had a single dose. Cervical specimens were collected from participants 18 months after marriage or 6 months after first childbirth, whichever was earlier, to assess incident and persistent HPV infections. Participants were invited to an annual cervical cancer screening once they reached age 25 years and were married.
A single dose of HPV vaccine provides similar protection against persistent infection from HPV 16 and HPV 18, the genotypes responsible for nearly 70% of cervical cancers, compared with that provided by two or three doses. Vaccine efficacy against persistent HPV 16 and 18 infection among participants evaluable for the endpoint was 95.4% (95% confidence interval [CI], 85.0-99.9) in the single-dose default cohort (2,135 women assessed), 93.1% (95% CI, 77.3-99.8) in the two-dose cohort (1,452 women assessed), and 93.3% (95% CI, 77.5-99.7) in three-dose recipients (1,460 women assessed).
Dr. Canlorbe reported no relevant financial relationships regarding the content of this article.
This article was translated from the Medscape French edition. An English version appeared on Medscape.com.