One-dose HPV-vaccination still works to prevent cancer

The HPV vaccine prevents infection by human papillomavirus, a sexually transmitted disease, specifically subtypes 16 and 18, that not only cause approximately 70% of cervical cancers, but also they cause most HPV-induced anal (95% linked to HPV), vulvar (50% linked), vaginal (65% linked), oropharyngeal (60% linked) and penile (35% linked) cancers.

The viruses are generally passed through genital contact, almost always as a result of vaginal, oral and anal sex. There is strong clinical evidence that the incidence of HPV infections have declined since the launch of the HPV vaccine and the subsequent steady rate of HPV vaccination.

In a community-based phase III trial of Cervarix (bivalent HPV vaccine) in Costa Rica, researchers reported that the Costa Rica Vaccine Trial (CVT) showed that the four-year vaccine efficacy against 12-month HPV subtypes 16 and 18 (HPV16/18) persistent infections was similarly high among women who received one, two, or the recommended three doses of the bivalent HPV16/18 vaccine. The researchers examined nearly 7,500 women, aged 18-25, in Costa Rica to determine both vaccine uptake (what percentage were vaccinated), number of doses, and HPV16/18 antibodies.

Some of the key results:

  • About 80% of the participants did get all three recommended doses, leaving about 20% who got one or two doses.
  • Researchers analyzed blood samples for HPV16/18 antibodies in randomized subsets who received one, two or three doses.
  • Antibodies to HPV16/18 was observed in 100% of women 48 months after vaccination with one, two or three doses. The only difference noticed that it appeared to take a slightly longer average period of time for 100% of the one-dose group.
  • Almost all participants in all vaccine dose groups were seropositive at approximately 1 month after receiving the first vaccine dose and remained seropositive throughout the 48 months follow-up period.
  • The researchers also compared “a natural infection group” against those who were vaccinated with Cervarix. For those vaccine deniers who say “natural infection is better”, the titers of HPV16/18 antibodies were 14-24X higher with two-doses of the vaccine, while the titers were 5-9X higher with one-dose vaccinations.

hpv-vaccine-controversy

The authors concluded:

The high efficacy after single dose suggests that long-term protection may not require the 5- fold higher titers induced by three doses of the vaccine. Fewer doses would be less expensive and logistically easier to deliver, therefore increasing vaccine accessibility worldwide. The findings also suggest that second generation vaccines might be strongly protective even if they do not induce the high levels of antibodies induced by the licensed vaccines as used according to current recommendations.

We know that the HPV vaccine is safe. Really safe in huge epidemiological studies. And we now have more evidence that it works, and it works better in protecting against HPV infections than so-called “natural immunity.” Unless you believe in lies from the antivaccinationists, HPV vaccines are one of the best ways to protect yourself from cancers.

 

If you need to search for accurate information and evidence about vaccines try the Science-based Vaccine Search Engine.

 

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The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor

Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!