Is a single dose of HPV vaccine enough?

PARIS — In an April press release, the World Health Organization (WHO) Strategic Advisory Group of Experts on Immunization (SAGE) reported the findings of their review of the efficacy of various dosing regimens for human papillomavirus (HPV). “A single-dose HPV vaccine offers solid protection against HPV, the virus that causes it” cervical cancerthat’s comparable to 2-dose schedules,” said WISE

This statement follows an article published in the November 2021 issue Lancet Oncology about a study in India† It found that a single dose of the vaccine provides comparable protection against persistent infection of HPV 16 and 18 as that of two or three doses.

Will this new information lead the French authorities to change their recommendations? What do French specialists think? At the 45th Congress of the French Association for Colposcopy and Cervical and Vaginal Diseases (SFPCPCV), Geoffroy Canlorbe, MD, PhD, of the Department of Gynecological and Breast Surgery and Oncology, Pitié-Salpêtrière Hospital, Paris, shared his thoughts.

Regarding the Indian study, Canlorbe pointed out that while the findings “need to be confirmed by other studies,” they are nonetheless “excellent news for developing countries where there are challenges when it comes to access to vaccination.”

India and France

During the congressional press conference, he went on to say that the findings “cannot be extrapolated” to France at this stage. This is because the situation in the country is different. HPV vaccination coverage is low; estimates put it at 23.7%, placing the country 28th out of 31 in Europe.

“This poor coverage has nothing to do with healthcare-related logistical or organizational issues, but has to do with people’s mistrust of vaccination. Here, people who get the first dose get the next one,” Canlorbe said. “The fact that you get two to three doses allows the person’s body to increase the production of antibodies and have a longer-lasting response to the vaccine.”

In addition, he drew attention to a number of limitations of the Indian study. Initially, the team planned to enroll 20,000 participants. Ultimately, there were about 17,000, and these were assigned to three cohorts: single-dose, two-dose, and three-dose. In addition, the primary target, initially targeting precancerous and cancerous lesions, was revised. The new aim was to compare the vaccine effectiveness of a single dose with that of three and two doses in protecting against persistent HPV 16 and 18 infection 10 years after vaccination. In about 90% of cases, the HPV infection cleared spontaneously within 2 years without causing lesions. Finally, the participants were women in India; therefore, the results cannot necessarily be generalized to the French population.

“This information has yet to be confirmed. However, to my knowledge, there are currently no new studies underway. The Indian study, on the other hand, is still in progress,” Canlorbe said.

“In France, I think for now we should stick to the studies that are currently available, which have shown the efficacy and safety of two or three doses,” he concluded. In support of this approach, he cited a recent study on the effects of the nationwide HPV vaccination program in England† there the vaccination rate is 80%.

This program was associated with a 95% risk reduction for precancerous lesions and an 87% reduction in cancers, confirming the good results already achieved by Sweden and Australia.

Commenting on the WHO’s position (which differs from that of the French experts), Jean-Luc Mergui, MD, a gynecologist in the colposcopy department and hysteroscopy at Pitié-Salpêtrière, and former president of the SFPCV, an eloquent comparison: “WHO also recommends 6 months of breastfeeding as a method of birth controlbut this is not what is recommended in France as the risk of getting pregnant still remains.”

Highlights of Indian Study

Partha Basu, MD, PhD, of the International Agency for Research on Cancer (IARC) in Lyon, France, and colleagues compared the efficacy of a single dose of Gardasil (HPV 9-valent vaccine, recombinant) with that of two and three doses in the protection against persistent HPV 16 and HPV 18 infection 10 years after vaccination.

According to the protocol, the plan was to recruit 20,000 unmarried girls aged 10-18 from all over India. Recruitment began in September 2009. In response to seven unexplained deaths reported in another ongoing HPV vaccination demonstration program in the country, the Government of India issued a notice in April 2010 to prohibit further recruitment and HPV vaccination in all clinical trials. to stop. At that time, Basu and his team had recruited 17,729 eligible girls.

After cessation of recruitment and vaccination, their randomized study was converted into a longitudinal, prospective cohort study by default.

Vaccinated participants were followed over a median duration of 9 years. A total of 4348 participants received three doses, 4980 two doses (at 0 and 6 months), and 4949 had a single dose. Cervical samples were collected from participants 18 months after marriage or 6 months after first delivery, whichever was earlier, to assess occasional and persistent HPV infections. Participants were invited to an annual cervical cancer screening once they reached the age of 25 and were married.

A single dose of HPV vaccine provides comparable protection against persistent infection of HPV 16 and HPV 18, the genotypes responsible for nearly 70% of cervical cancers, compared to those from two or three doses. Vaccine efficacy against persistent HPV 16 and 18 infection among participants evaluable for the endpoint was 95.4% (95% CI, 85.0 – 99.9) in the standard single-dose cohort (2135 women evaluated ), 93.1% (95% CI, 77.3 – 99.8). ) in the two dose cohort (1452 women assessed) and 93.3% (95% CI, 77.5 – 99.7) in three dose recipients (1460 women assessed).

Canlorbe did not report any relevant financial relationships related to the contents of this article.

This article has been translated from the Medscape French edition.

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