Single-dose HPV vaccine ‘highly effective’

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A new single-dose human papillomavirus vaccine could help the World Health Organization meet its goal of vaccinating 90% of 15-year-old girls against HPV by 2030. Matthew Busch for The Washington Post via Getty Images
  • Human papillomavirus (HPV) causes cervical cancer and mainly affects people in low- and middle-income countries.
  • Recommendations currently suggest that women and girls need multiple doses of an HPV vaccine for it to be effective.
  • In the present study, the researchers found that a single dose of an HPV vaccine was as effective as a multi-dose vaccine.

A single-dose human papillomavirus (HPV) vaccine may be as effective as the three-dose regimen that’s the current standard, a new study in Africa has found.

The study, published in NEJM proofcould help accelerate female vaccination rates against the virus and reduce its effectiveness at the population level.

According to the World Health Organization (WHO) 342,000 women died from cervical cancer in 2020. 90% of these deaths occurred in low- and middle-income countries.

HPV – and in particular its serotypes 16 and 18 – account for 50% of high-grade cervical pre-cancer.

Currently, women and girls can be vaccinated against HPV, but acc US Centers for Disease Control and Prevention (CDC), this requires a two- or three-dose regimen.

The need for multiple doses is slowing vaccination rates in women and girls. This is particularly the case in low- and middle-income countries, where there is less infrastructure and less money to enable rapid and widespread vaccination.

Researchers have found that as more people get vaccinated, the spread of HPV is reduced at the population level.

According to WHO Deputy Director-General Dr. Princess Nothemba (Nono) Simelela, the results of the new study could help eliminate cervical cancer.

“I firmly believe that eliminating cervical cancer is possible,” says Dr. Simelela.

“In 2020 the Cervical Cancer Elimination Initiative was created to address several challenges including inequality in access to vaccines. This single-dose recommendation has the potential to accelerate our goal of vaccinating 90% of girls aged 15 by 2030.”

The randomized, controlled study involved 2,275 women and girls between the ages of 15 and 20.

Requirements included being negative for the human immunodeficiency virus, being sexually active, having no more than five sexual partners in their lifetime, and not having been previously vaccinated against HPV.

The participants were randomly assigned to one of three groups.

A bivalent HPV vaccine – which elicits an immune response to two different antigens – was given to 760 of the participants. A nonavalent HPV vaccine – which induces an immune response to nine different antigens – was given to 758 of the participants. Finally, 757 participants were given a meningococcal meningitis vaccine.

The researchers found that single doses of both the bivalent and non-avalent vaccines were 97.5% effective against HPV 16 and 18 at 18 months.

dr Ruanne Barnabas — chief of the infectious diseases unit at Massachusetts General Hospital and the study’s lead investigator — says that “the effectiveness of a single dose was the same as that of multiple doses.”

Corresponding dr Alejandro Cravioto – the Chair of the WHO Strategic Advisory Group of Experts on Immunization (SAGE) – the results of the study mean that a single dose of an HPV vaccine can be recommended for many girls and women.

dr Cravioto says that “SAGE urges all countries to adopt HPV vaccines and prioritize catching up on missed and older girl cohorts through multiple age groups.”

“These recommendations will enable more girls and women to get vaccinated and thus prevent them from developing cervical cancer and all its consequences over the course of their lives.”

While the evidence for a new single-dose regimen is exciting, it will also require political and economic support for low- and middle-income countries to realize its potential.

dr Simelela says, “We need political commitment complemented by equitable pathways for HPV vaccine accessibility. Not doing so is an injustice to the generation of girls and young women who may be at risk for cervical cancer.”

“The option for a single dose of the vaccine is less expensive, less resource intensive and easier to administer. It makes it easier to run catch-up campaigns for multiple age groups, reduces the challenges associated with finding girls for their second dose, and allows financial and human resources to be reallocated to other health priorities.”

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