Today, a hot topic about hpV vaccines is in the spotlight: #世卫称接种 1 dose of HPV is comparable to 2 to 3 doses#
Image source: Screenshot of The Paper's Weibo
From 4 to 7 April, the World Health Organization convened a meeting of the Advisory Group of Experts on Immunization Strategies (SAGE) to review the evidence for 1 dose of HPV vaccination and concluded that just 1 dose of HPV vaccine can produce the same immune effect as 2 to 3 doses, effective in preventing cervical cancer caused by persistent HPV infection.
I believe that the netizens who saw this hot search, the idea is sauce aunt's:
Unvaccinated: "Oye! Just get a shot!"
After the vaccination: "Nani? Then didn't I get two or three shots in vain?"
In fact, neither of these ideas is necessary.
Is 1 shot really enough?
This information has been oversimplified, and we will first talk about the WHO document [1].
Image source: Screenshot of the WHO official website
The meeting recommended an updated HPV vaccination program, which is divided into the following points:
- Girls aged 9 to 14 years can choose between a single dose or a two-dose regimen;
- For young women aged 15 to 20 years, a single or two-dose regimen can be used,
- For women over 21 years of age, a two-dose regimen should be given at an interval of 6 months;
- Immunocompromised people, including those infected with HIV, are given at least two doses and, if feasible, three doses.
Does this information prove that the WHO doesn't think it makes sense to get 3 doses of the HPV vaccine?
Not really.
In the past, the 3-dose vaccination procedure was established because clinical studies have found that 3-dose vaccination can achieve a very desirable protective effect.
There have been studies and discussions about 1 dose and 2 shots in recent years, but current studies on the protective efficacy of a 1 shot vaccine are not enough to support its reversal and replacement of the 3-shot regimen.
WHO's recommendations are largely based on a recent article published in the New England Journal of Medicine (NEJM) titled "Efficacy of single doses of HPV vaccine in young African women"[2], which does lead to similar conclusions about the effectiveness of 1 dose of HPV vaccine and multiple doses against persistent infections.
But the study also has a number of problems:
1. The observation time is short, this study only looked at the data of 18 months after 1 injection, and there is no long-term data, knowing that most people infected with HPV will be cleared by the immune system within 2 years;
2. The observation endpoint was "whether hpv is still persistent infection", rather than cervical cancer or precancerous lesions that everyone is more concerned about, so the results are not a substitute for clinical outcome indicators such as cervical cancer or genital warts;
3. There is no evidence that 1 dose and 2 to 3 injections are equally effective in preventing cervical cancer or precancerous lesions, so no equal sign can be drawn.
The core problem is that the protective effect on cervical cancer is not yet clear. All in all, the conclusions of this article may also be exaggerated to some extent.
In addition, the WHO recommendation has a very important premise that it only applies to those HPV vaccine products that have been involved in the study. Simply put, not all brands and all types of HPV vaccines are suitable for single-shot procedures.
Since current evidence does not prove that 1 dose is equivalent to 2 or 3 shots, and there is a lack of studies on long-term protective effects, why did WHO propose such an adjustment?
Single-dose procedures are more likely to be completed
Global goal to eliminate cervical cancer by 2030
In this document, the WHO mentions that a very pressing problem is now encountered.
In November 2020, WHO launched the Global Strategy to Accelerate the Elimination of Cervical Cancer, which sets a goal of eliminating cervical cancer globally by 2030.
Image source: Screenshot of the WHO official website
However, due to the COVID-19 pandemic and other reasons, the speed of HPV vaccination and coverage has slowed down, adding a lot of pressure to achieve the goal. So how can we quickly increase HPV vaccine coverage?
Thus, a very clear recommendation was made at this meeting: the introduction of a single dose of vaccination. This approach has the potential to speed up coverage and reduce operational costs and difficulties.
The advantages of the 1-dose procedure are that it provides a high level of protection, can reach more people when vaccine supply and vaccination capacity are insufficient, and is more cost-effective, i.e. less average doses are required for each case of cervical cancer prevention.
Theoretically, it would be equivalent to strengthening the protection of broader groups.
In short, the single-needle procedure is better to operate and save costs for the whole, but it does not mean that it is more effective for the individual, how to weigh, how to choose, perhaps we need more evidence.
What's next?
From the perspective of immunization procedures, based on the information given by the WHO, it is necessary to collect more data on the effectiveness of the protection of "different immunization procedures" of "different HPV vaccines" against diseases (cervical cancer), and at the same time pay more attention to the tertiary prevention related to cervical cancer, so that in the future, more women around the world can be protected by HPV vaccines and achieve the goal of "eliminating cervical cancer".
For friends who are ready to fight, are playing, and have already been beaten, before there is more conclusive evidence or official policy updates, it is best to receive HPV vaccines in accordance with the currently approved immunization procedures to achieve the most ideal protection; the current HPV vaccination procedures in mainland China have not changed, and before the instructions are modified, they can only be vaccinated according to the instructions.
However, if the vaccination procedure cannot be completed for various reasons, there is no need to worry about hitting or not being safe, as 1 or 2 doses of HPV vaccine have been shown to provide reliable immune persistence.
This article is co-authored by experts
bibliography
[1]https://www.who.int/news/item/11-04-2022-one-dose-human-papillomavirus-(hpv)-vaccine-offers-solid-protection-against-cervical-cancer
[2] DOI:https://doi.org/10.1056/EVIDoa2100056
Planning and production
Curator: Deanna | Executive Producer: Feidi, Eric
Illustration: See annotation | Cover image source: Dr. Lilac design team