1 dose as effective as 2 for HPV vaccine: 5 study notes

One dose of an HPV vaccine was found to be “noninferior” to two doses, according to a study published Dec. 3 in The New England Journal of Medicine. 

More than 20,000 participants enrolled in the randomized study of two HPV vaccines, one bivalent and one nonavalent. The study was led by researchers from the National Cancer Institute and Costa Rica’s biomedical investigation agency.

Here are five things to know from the study:

1. The noninferiority margin for the vaccine was 1.25 infections per 100 participants — for HPV16 or HPV18 — occurring between study months 12 to 60 and persisting for at least six months.
   
   
2. The difference between one and two doses of the bivalent vaccine was -0.13 infections per 100 participants.
   
   
3. The difference between one and two doses of the nonavalent vaccine was 0.21 infections per 100 participants.
   
   
4. The vaccine effectiveness was at least 97% in each of the four trial groups.
   
   
5. “One dose of either a bivalent or nonavalent HPV vaccine provided protection against HPV16 or HPV18 infection and was not inferior to two doses,” the study authors wrote. 

Read the full study here.