Thursday, September 21, 2023

Is The Hpv Vaccine 2 Or 3 Doses

Summary Of Key Findings

UW research: 1 HPV vaccine dose as effective as 2-3

Immunogenicity. In the 9vHPV clinical trial that was the basis for FDA approval of a 2-dose series, participants were girls and boys aged 9 through 14 years, compared with young females aged 16 through 26 years . Among 1,377 participants, 97.9% seroconverted to all nine vaccine-preventable HPV types by 4 weeks after the last dose. For girls and boys who received 2 doses of 9vHPV 6 months apart or 12 months apart , noninferiority criteria were met for seroconversion and GMTs. Furthermore, GMTs were significantly higher for all 9vHPV types among persons aged 9 through 14 years who received 2 doses compared with females aged 1626 years who received 3 doses . Six additional studies found similar results for 4vHPV and 2vHPV . Immunogenicity was found to be noninferior with 2 doses in persons aged 9 through 14 years compared with 3 doses in a group in which clinical efficacy was demonstrated .

Duration of protection. Through 10 years of follow-up from clinical trials, no evidence of waning protection after a 3-dose series of HPV vaccine has been found . Because antibody kinetics are similar with 2-dose and 3-dose series, duration of protection is also expected to be long-lasting after a 2-dose series .

What Are The Different Types Of Hpv And What Do They Do

There are more than 100 different types of HPV, and around 40 that affect the genital area.

HPV is very common and can be caught through any kind of sexual contact with another person who already has it.

Most people will get an HPV infection at some point in their lives and their bodies will get rid of it naturally without treatment.

But some people infected with a high-risk type of HPV will not be able to clear it.

Over time, this can cause abnormal tissue growth as well as other changes, which can lead to cancer if not treated.

High-risk types of HPV are linked to different types of cancer, including:

Infection with other types of HPV may cause:

  • genital warts small growths or skin changes on or around the genital or anal area they’re the most common viral sexually transmitted infection in the UK
  • skin warts and verrucas not on the genital area
  • warts on the voice box or vocal cords

Hpv Vaccine For Girls And Boys

The HPV vaccine has been offered to girls in their first year of secondary school since 2010. This is because the most common cancer caused by the HPV virus is cervical cancer which only affects women.

Since September 2019, boys have also been offered the HPV vaccine. This is because HPV can cause cancers and genital warts in boys too.

The more young people vaccinated – both boys and girls – the better we can control the spread of the infection.

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Efficacy Of Less Than 3 Doses To Prevent Genital Warts

Genital warts have a short incubation period of 1 to 6 months and a much shorter natural history than that of cervical neoplasia. The earliest evidence of the effectiveness of the 4vHPV vaccination at the population level is indicated by the reduction in the incidence of genital warts. Such evidence was obtained from ecological studies in the countries that introduced 4vHPV vaccines in the national immunization programs. Some of these studies also reported the efficacy of fewer than 3 doses of the 4vHPV vaccine in prevention of genital warts.

Safety And Adverse Events

Vaccine schedule for HPV, Hep B to switch to 2 doses in ...

Common and local adverse events

Based on pre-licensure clinical trials, involving more than 15,000 subjects given HPV4 vaccine and 12,000 given HPV2 vaccine, the most common adverse events in persons receiving HPV vaccines were: injection site pain , swelling or redness . These adverse events were observed significantly more often following HPV vaccine than following active vaccine or placebo controls. In over 94% of subjects who received HPV vaccine, the reactions were mild to moderate in intensity, resolved over a few days, and did not prevent completion of the immunization schedule. Systemic adverse events, such as fatigue, myalgia, headache, fever, and nausea, generally occurred with comparable frequency in vaccine and control groups. The safety profile of HPV9 vaccine is comparable to HPV4 vaccine, although mild to moderate intensity injection site reactions are more common following receipt of HPV9 vaccine.

Since vaccine licensure, hundreds of millions of doses of HPV vaccine have been distributed worldwide. Data from post-licensure safety surveillance reporting systems have consistently mirrored the pre-licensure data with the most frequently reported adverse events following immunization being vaccination site reactions and muscle pain.

Less common and serious or severe adverse events
Other reported adverse events and conditions
Guidance on Reporting Adverse Events Following Immunization

Contraindications and precautions

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Where Can I Get Vaccinated

The best place to go for vaccinations is your family medical clinic. They have your medical records and can check to see if youve already had a particular vaccination. Either your doctor or a nurse can give the vaccination.If you dont have a family doctor, you can go to one of the after-hour medical clinics. Phone them first to make sure they can help you with the vaccination you need.You can find a clinic near you on the Healthpoint website. Put in your address and region, and under Select a service, click on GPs/Accident & Urgent Medical Care.Vaccines on the National Immunisation Schedule are free. Other vaccines are funded only for people at particular risk of disease. You can choose to pay for vaccines that you are not eligible to receive for free.

Vaccination Of Specific Populations

Pregnancy and breastfeeding

HPV vaccines are not recommended for use in pregnancy because data on HPV vaccination in pregnancy are limited. HPV vaccine, however, has not been causally associated with adverse outcomes of pregnancy or adverse events to the developing fetus. In the absence of data, it is recommended that initiation of the HPV vaccine series should be delayed until after completion of the pregnancy. If a woman is found to be pregnant after initiating the vaccination series, completion of the series should be delayed until after pregnancy. No intervention is required if vaccine has been administered during pregnancy.

Vaccine recipients and health care providers are encouraged to report any exposure to HPV4 or HPV9 vaccine during pregnancy to the vaccine manufacturer at 1-800-567-2594. Exposure to HPV2 vaccine during pregnancy should be reported to the vaccine manufacturer at 1-800-387-7374.

There are limited data on the effects on breastfed infants from HPV vaccination of their mothers however, there have been no reported adverse events thought to be vaccine-related. Therefore, HPV vaccine may be administered to breastfeeding women.

Refer to Immunization in Pregnancy and Breastfeeding in Part 3 for additional information about vaccination of women who are pregnant or breastfeeding.

Immunocompromised persons

Refer to Immunization of Immunocompromised Persons in Part 3 for additional information about vaccination of people who are immunocompromised.

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Vaccine Efficacy In People Already Infected With Hpv

In women who are vaccinated regardless of their baseline HPV status , vaccine efficacy is lower than in HPV-naive women. This suggests reduced vaccine effectiveness among females who are already sexually active. This is because the HPV vaccines are prophylactic vaccines they prevent primary HPV infection.

Vaccination does not:

  • treat an existing HPV infection
  • prevent disease that may be caused by an existing vaccine HPV-type infection30,117-119

HPV vaccine protection is believed to be predominantly antibody mediated. Even low levels of antibodies can stop HPV entering the basal epithelial cells. HPV can only access the basal cell at sites of microtrauma, where there is a breach in the epithelium, and circulating HPV antibodies from sera are present at these sites.41

Because antibodies prevent viral entry, vaccination may still benefit sexually active men and women by protecting them against:

  • new infections with other vaccine-preventable HPV types
  • reinfection with vaccine-preventable types they have previously been exposed to for example, from an infected partner
  • auto-inoculation of existing persistent HPV infection to other sites

Is The Hpv Vaccine 2 Or 3 Doses Of Teenagers

New findings show that a single dose of the HPV vaccine is highly effective compared to the 3-dose

Is the HPV vaccine 2 or 3 doses of teenagers?

The HPV vaccines are given as either 2 or 3 doses over a 6 month period. Children who are 9 to 14 years of age need 2 doses given at least 6 months apart. People 15 years of age and older need 3 doses.

You can find more information about HPV vaccines here.

– Immunization Nurse

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When Is Hpv Vaccine Given

In New Zealand, the HPV vaccine is available free for everyone aged 926 years.

  • It is recommended to be given to children aged 1112 years.
  • For children aged 914 years, the HPV vaccine is given as 2 doses, at least 5 months apart. This age group develops a stronger immune response than those vaccinated when they are older.
  • People aged 15 years and older will need 3 doses of the vaccine, spaced over 6 months.
  • Each dose is given as an injection into the muscle of your arm or leg.

Children are offered the vaccine at most schools, usually in Year 7 or 8. The vaccine is also available free from general practices and some other health centres.

People aged 27 years or older may still benefit from receiving a course of 3 HPV vaccine doses. If you have not started the course by age 27, you need to buy the vaccine doses through your family doctor or Family Planning Clinic. The HPV vaccine is recommended in people aged 27 years and older who:

  • have had little previous exposure to HPV and are now likely to be exposed
  • are men who have sex with men
  • have HIV.

Hpv Vaccine Schedule And Dosing

can be started at age 9 years
Catch-up Vaccination*
Some adults age 2745 years,if not adequately vaccinated

About 85% of people will get an HPV infection in their lifetime. Vaccinating all 1112-year-olds can protect them long before they are ever exposed.

CDC recommends two doses of HPV vaccine for all adolescents at age 11 or 12 years.

  • A 2-dose schedule is recommended for people who get the first dose before their 15th birthday. In a 2-dose series, the second dose should be given 612 months after the first dose .
  • The minimum interval is 5 months between the first and second dose. If the second dose is administered after a shorter interval, a third dose should be administered a minimum of 5 months after the first dose and a minimum of 12 weeks after the second dose.
  • If the vaccination schedule is interrupted, vaccine doses do not need to be repeated .
  • Immunogenicity studies have shown that two doses of HPV vaccine given to 914-year-olds at least 6 months apart provided as good or better protection than three doses given to older adolescents or young adults.

A 3-dose schedule is recommended for people who get the first dose on or after their 15th birthday, and for people with certain immunocompromising conditions.

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Immunizing Agents Authorized For Use In Canada

HPV vaccines

  • CERVARIX® , GlaxoSmithKline Inc. .
  • GARDASIL® , Merck Canada Inc. .
  • GARDASIL®9 , Merck Canada Inc.

For complete prescribing information, consult the product leaflet or information contained within the product monograph available through Health Canada’s Drug Product Database.

Refer to Contents in Immunizing Agents Available for Use in Canada in Part 1 for a list of vaccines available for use in Canada and their contents.

Efficacy Of Fewer Than 3 Doses Against Virological Endpoints


The impact of the vaccines can be assessed by documenting the decline in the prevalence of infection from HPV types targeted by the vaccines .

A phase III randomized controlled study was conducted by the National Cancer Institute of USA in the Guanacaste province of Costa Rica to evaluate the safety and efficacy of the bivalent vaccine in women aged 18 to 25 y An ancillary post-hoc analysis of the study evaluated the efficacy of fewer than 3 doses in the participants who received 2 doses or a single dose due to colposcopy referral, pregnancy, adverse events or non-compliance. The vaccine efficacies against 12 months incident persistent HPV 16/18 infection after a median follow up of 4.2 y in the women negative for HPV 16/18 DNA at baseline were 80.9% , 84.1% and 100% among the recipients of 3 doses, 2 doses and a single dose respectively. This was the first study to report the HPV vaccine efficacy against virological endpoints with a single or 2 doses of the vaccine. However, concerns were expressed due to possible selection bias and fewer participants, especially in the single dose arm.

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Current Status Of Indigenous Vaccine Development

Bharati and Ganguly argue that India needs to develop and manufacture its own HPV vaccine in order for it to be affordable and cheap so as to reach of most people and vaccinate the target population. Several private sector organizations like the Indian Immunologicals Ltd., Hyderabad, Shantha Biotechnics Ltd. , Hyderabad, Bharat Biotech Interl Ltd., Hyderabad, Serum Institute of India Ltd., Pune, Gennova Biopharmaceuticals Ltd., Pune, Virchow Biotech Pvt. Ltd. Hyderabad and also public sector organizations like Translational Health Science and Technology Institute, Gurgaon, Haryana and Institute of Cytology and Preventive Oncology, Noida, Uttar Pradesh are actively involved in HPV vaccine development efforts in India.

Studying The Effectiveness Of Two

Over the course of the study period, 830 participants were randomly divided into groups that received either two or three doses of the HPV vaccine at zero and six months, or zero, two, and six months, respectively. One month after the last dose, researchers checked levels of the immune systems response to the vaccine and found that the two doses provide a comparable and just as protective response as the three doses.

The study took place at three different centers between 2007 and 2008, and was approved by Health Canada and an external monitoring board. Participants were otherwise healthy girls between the ages of 9 and 13 years or young women between the ages of 16 and 26 years and were limited to four or less total lifetime sexual partners. Participants were excluded if they were pregnant at the time of enrollment or vaccination, had a history of sexually transmitted diseases such as genital warts, or had previously received an HPV vaccine. The vaccinations were commercially available options, and were administered to the participants as they would have been in a non-study setting.

In the following two and a half years, the majority of participants in both groups retained antibodies for the HPV vaccinations, hinting at the longevity and effectiveness of a two-dose vaccination schedule, although the immunogenicity levels were found to be inferior to those on a three-dose schedule at 36 months.

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Contraindications And Precautions Of Hpv Vaccine

Contraindications for HPV vaccine include

  • A severe allergic reaction after previous dose or to a vaccine component

  • Pregnancy

Although HPV vaccines are not recommended for pregnant women, pregnancy testing is not needed before vaccination. If pregnancy is diagnosed after the vaccination series has been started, no intervention is needed, but the remaining doses of the series should be delayed until pregnancy is completed.

The main precaution with HPV vaccine is

  • Moderate or severe acute illness with or without fever

Vaccine Efficacy In Females 1626 Years Of Age

Hope as trial shows single dose of vaccine is highly effective

Efficacy of the and 9vHPV vaccines has been assessed in females in several international clinical trials.

2vHPV and 4vHPV vaccines

In women aged approximately 1626 years who are naive to HPV types 16 and 18 before vaccination, the 2vHPV and 4vHPV vaccines are both about 90100% effective at preventing type-specific persistent infection and related cervical disease.

The vaccine is 100% effective against vaginal and external anogenital lesions associated with HPV types 6, 11, 16 and 18 in women.107-112

These include:

vaccine also provides considerable cross-protection against cervical infection with HPV types 31, 33 and 45.113

9vHPV vaccine

The 9vHPV vaccine has established efficacy against the following neoplasias and cancers that are associated with HPV types 31, 33, 45, 52 and 58:114

  • cervical
  • vulval
  • vaginal

A clinical trial of 9vHPV vaccine in women aged 1626 years established non-inferiority of the 9vHPV vaccine against the 4vHPV types . Incidence of disease endpoints was similarly low in women vaccinated with either 9vHPV or 4vHPV

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Study Compares Effectiveness Of Two Vs Three Doses Of Hpv Vaccine For Girls And Young Women

American Medical Association
With the number of doses and cost of human papillomavirus vaccines a barrier to global implementation, researchers have found that girls who received two doses of HPV vaccine had immune responses to HPV-16 and HPV-18 infection that were not worse than the responses for young women who received three doses, according to a new study.

With the number of doses and cost of human papillomavirus vaccines a barrier to global implementation, researchers have found that girls who received two doses of HPV vaccine had immune responses to HPV-16 and HPV-18 infection that were noninferior to the responses for young women who received three doses, according to a study in the May 1 issue of JAMA, a theme issue on child health. The authors note that more data on the duration of protection are needed before reduced-dose schedules can be recommended.

Simon R. M. Dobson, M.D., of the University of British Columbia, Vancouver, presented the findings of the study at a JAMA media briefing.

The researchers found that the geometric mean titer antibody levels in girls receiving 2 doses were noninferior to the respective GMTs in women receiving 3 doses for all 4 genotypes, with GMT ratios of 2.07 for HPV-16 and 1.76 for HPV-18. “Girls given 2 doses vs. 3 doses had a noninferior antibody response for all 4 vaccine genotypes,” with GMT ratios of 0.95 for HPV-16 and 0.68 for HPV-18.

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