June 26, 2022

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Harvard University: HPV vaccination after 26 years may not be so effective

Harvard University: HPV vaccination after 26 years may not be so effective



 

Harvard University: HPV vaccination after 26 years may not be so effective. 

As the first human cancer vaccine, the human papillomavirus (HPV) vaccine can be described as a well-deserved vaccine star in recent years.

In addition to cervical cancer, it also has a good preventive effect on various cancers such as cervical cancer and anal cancer.

 

As the first human cancer vaccine, the human papillomavirus (HPV) vaccine can be described as a well-deserved vaccine star in recent years.

In addition to cervical cancer, it also has a good preventive effect on various cancers such as cervical cancer and anal cancer.

 

However, for people who miss the optimal time for vaccination, can timely supplementation of HPV vaccine obtain equivalent health benefits?

 

According to the latest mathematical models of Harvard University in the United States and the Cancer Council of NSW, Australia, even assuming that the HPV vaccine can prevent 95% of cervical cancers, it is not necessarily cost-effective to vaccinate HPV after the age of 26 in the United States.

 

Jane Kim, KTLi, professor of health economics at the Harvard TH School of Public Health, said in an interview: “Our research found that in the United States, the age limit for vaccination was raised to 26 years old. The additional health benefits are minimal, and the cost-benefit ratio is much lower than that of vaccination during adolescence.”

 

This paper titled “Human papillomavirus vaccination for adults aged 30 to 45 years in the United States: A cost-effectiveness analysis” was published in PLOS Medicine on March 11, 2021 .

 

Harvard University: HPV vaccination after 26 years may not be so effective

 

 

Vaccination after 26 years of age may not be so effective

Jane Kim pointed out that the current HPV vaccine is preventive, so it is most effective to vaccinate before being infected with HPV.

Generally, humans may be exposed to human papilloma virus shortly after the start of sexual activity. Once infected, the vaccine does not eliminate the virus.

 

The researchers said that their conclusions were mainly derived from the microscopic models of HPV infection and cervical cancer by two independent modeling teams.

These models have been empirically calibrated to reflect the medical costs of HPV-related cancers in the U.S. population, and standardized considerations such as vaccination rate, vaccine efficacy, cervical cancer screening and cost, etc.

The cost-effectiveness of extending the upper limit of HPV vaccination to 30, 35, 40 or 45 years of age.

 

The study used the medical sector’s perspective, including direct medical costs for diseases, vaccination, and cervical cancer screening.

Both models also take into account data on HPV transmission, natural history of cervical cancer, HPV vaccination, and cervical screening, diagnosis, and treatment. Based on gender, age, and level of sexual activity, HPV transmission was modeled as a function related to the relationship between partners in both models.

HPV infection may spread, depending on the number of new partners, the partner’s infection status, the likelihood of being infected if a partner is infected with HPV, and the duration of the partnership.

 

Harvard University: HPV vaccination after 26 years may not be so effective
Figure | Schematic diagram of Cervical Cancer Intervention and Surveillance Modeling Network (CISNET-Cervical) model (source: paper)

 

 

In order to visually calculate the impact of HPV vaccines on health and life expectancy, the researchers adopted the concept of quality-adjusted life years (QALY, Quality-adjusted life years).

Different from other health evaluation indicators, QALY is a comprehensive indicator that simultaneously considers the impact of health interventions (such as HPV vaccination) on the patient’s production quality and survival time.

 

The analysis estimates the long-term results of expanding the scope of HPV vaccination to women and men under the age of 45, and predicts life-long health and economic data for multiple groups of the U.S. population from 2019 to 2119.

 

Studies have shown that based on the existing vaccine prices in the United States, the incremental cost-effectiveness ratio (ICER) of raising the upper age limit for HPV vaccination to 45 years old is between US$315,700 and US$440,600 per QALY, which is greater than the general upper limit of US$200,000.

Therefore, researchers believe that HPV vaccination in the United States for adults over 26 is not necessarily worth the money.

 

 

So, what should an adult after 26 years old do?

Although the paper has just been published, its data and conclusions have been adopted by the Centers for Disease Control and Prevention (CDC) as early as 2019 as a guideline for HPV vaccination.

 

According to US official recommendations, teenagers 11-12 years old need to be vaccinated against HPV and can be re-vaccinated before the age of 26.

For adults over 26 years old, there are no special recommendations. Clinicians and patients can make decisions based on their individual circumstances.

 

It should be pointed out that due to the different prices, the cost and benefit of HPV vaccination in different countries are quite different. Take Australia as an example.

The government of that country implemented a national immunization plan in 2007 to provide free HPV vaccines to all teenagers aged 12-13. Therefore, the results of this study are only for the specific cost and benefit of vaccination in the United States.

 

For older people in the United States (30, 34, 40, 45 years old), the cost of HPV vaccination is high and the benefits are low.

The relevant departments in the United States have also implemented two prevention strategies: The promotion of HPV vaccination among men and men has provided some herd immunity benefits for older people who have not been vaccinated; the second is to carry out cervical screening for older women.

 

Jane Kim also said: “When you vaccinate people in their 30s and 40s, many people have been exposed to HPV, so in these older people, the health benefits of the vaccine will really diminish. But It needs to be emphasized that cervical cancer screening is still an effective and economical way to protect women from cervical cancer.”

 

However, the researchers also acknowledge that this study has several important limitations. Including the disease burden of non-cervical cancer may change over time.

The authors point out that there is a lack of trial data on the effectiveness of vaccines for men over 26 years of age.

The researchers also pointed out that future studies are needed to more accurately assess the health outcomes of the elderly population receiving HPV vaccines.

 

About HPV vaccine

Among female malignant tumors, the incidence of cervical cancer is second only to breast cancer, and most cervical cancers are caused by HPV infection.

 

HPV vaccines are commonly known as cervical cancer vaccines and are used to prevent specific HPV infections.

Currently, there are three types of HPV vaccines on the global market: divalent, quadrivalent, and ninth-valent. The “valence” represents the type of virus that the vaccine can prevent.

In cervical cancer cases, up to 90% of cases are related to HPV-6/11.

 

Among American women born between 1969 and 2009, approximately 300,000 people may be diagnosed with cervical cancer.

 

Since the 1990s, two scientists have made outstanding contributions to the development of HPV vaccines. One is Dr. Ian Frazer, a scientist from the University of Queensland in Australia, and the other is Dr. Zhou Jian, a Chinese scientist.

 

Harvard University: HPV vaccination after 26 years may not be so effective
Picture | Professor Ian Frazer, one of the inventors of the HPV vaccine (Source: medicine.uq.edu.au/)

 

 

On July 18, 2016, the global medical and healthcare company GlaxoSmithKline (GSK) announced that the company’s “Cyrix” has been approved by the State Food and Drug Administration of China, becoming some countries’s first approved HPV vaccine for the prevention of cervical cancer. 

At present, more than 100 countries and regions around the world have approved HPV vaccines, and the number of HPV vaccines used exceeds 100 million.

 

 

 

 

Harvard University: HPV vaccination after 26 years may not be so effective

(source:internet, reference only)


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