关键词：世界卫生组织，加速消除母婴传播乙型肝炎问题，生命健康
世界卫生组织（世卫组织）最新估算，在1980年代到2000年代初未接种乙肝疫苗期，5岁以下儿童感染慢性乙肝病毒的百分比约为5%，到2019年已降至1%以下。
这标志着已实现可持续发展目标所确定的关于消除病毒性肝炎的一项重要具体目标，实现了到2020年将5岁以下儿童乙肝病毒感染率控制在1%以下这一具体目标。
世卫组织总干事谭德塞博士指出：“所有婴儿都应接种乙肝疫苗，以免长大后死于乙型肝炎。实现这一重要具体目标意味着，未来几代人肝损伤和肝癌病例数将大幅减少。预防乙型肝炎母婴传播和幼儿期传播是控制这一疾病和拯救生命的最重要战略。即使在COVID-19大流行期间，我们也必须确保母亲和新生儿能够获得拯救生命的服务，包括接种乙型肝炎疫苗”。
世卫组织于2020年世界肝炎日呼吁再接再厉，一致采取大力行动，检测孕妇和对有需要者采取抗病毒预防措施，维持和扩大乙型肝炎免疫接种，并为新生儿接种出生剂次疫苗，加紧预防乙型肝炎母婴传播。
全球共有2.5亿多人感染了慢性乙型肝炎病毒。婴儿尤其脆弱：大约90%感染乙型肝炎病毒的儿童在出生第一年即成为慢性乙型肝炎病毒携带者。乙型肝炎病毒损伤肝部，每年造成近90万人死亡。
预防乙型肝炎
通过接种安全有效的疫苗，婴儿可以免受乙肝病毒感染。乙肝疫苗可提供95%以上的感染防护。世卫组织建议为所有婴儿在出生后尽早（最好是在24小时内）接种第一剂乙型肝炎疫苗，此后应再接种至少两剂疫苗。
过去二十年来，在全球疫苗免疫联盟的大力支持下，全球推广乙型肝炎疫苗接种在公共卫生领域取得了巨大成就，儿童乙肝病毒感染率大幅下降。2019年，全世界3剂乙肝疫苗覆盖率达到85%，而在2000年覆盖率大约只有30%。然而，在出生后24小时内获得第一剂关键疫苗接种的机会仍不平等。全球出生剂次覆盖率为43%，而世卫组织东地中海区域的覆盖率只有34%，世卫组织非洲区域的覆盖率仅有6%。
全球艾滋病毒、肝炎和性传播感染规划司司长Meg Doherty博士说，“推广及时接种乙肝疫苗出生剂次是防止乙肝母婴传播的基石。在一些国家，尤其在尚未实行出生剂次疫苗接种的撒哈拉以南非洲地区的国家中，重点是确保尽早提供此项疫苗接种服务”。
保护儿童的另一项措施是向孕妇提供抗病毒治疗，以减少乙肝病毒母婴传播。世卫组织建议对所有孕妇进行乙肝病毒常规检测，并建议在妊娠期尽早对孕妇进行艾滋病毒和梅毒检测。根据关于孕妇及其子女抗病毒预防措施安全性和有效性的新证据，世卫组织今天发布了两项新建议：
1.乙肝感染检测结果呈阳性且血液中乙肝病毒含量（也称为乙肝病毒载量）较高的孕妇应在怀孕28周至分娩前接受替诺福韦预防性抗病毒治疗。在世界上许多国家中，替诺福韦这一抗病毒药物每月治疗费用低于3美元。
2.在无法检测乙肝病毒载量的环境中，世卫组织建议采用低成本的检测HBeAg方法，以确定为哪些妇女提供预防性抗病毒治疗。
在乙型肝炎免疫接种（包括及时接种出生剂次）高覆盖率的国家中，常规检测孕妇乙肝病毒感染和对有需要者采取抗病毒预防措施可以进一步防止母婴传播。
Doherty博士还指出：“阻断乙肝病毒的垂直传播是全球‘三消除’计划的一项关键内容。这项计划的目标是，消除在低收入和中等收入国家中流行的母婴传播艾滋病毒、梅毒和乙肝病毒感染问题”。
消除母婴传播乙肝病毒也是实现世卫组织全球肝炎战略目标的重要步骤。世卫组织全球肝炎战略目标是，与2015年水平相比，将肝炎新发感染率降低90%，死亡人数减少65%。
COVID-19大流行疫情危及今后进展
在最糟糕的情况下，假如乙肝病毒疫苗出生剂次接种率和儿童乙肝疫苗覆盖率受到严重影响（一年受影响程度分别为60%和20%），并假如在COVID-19疫情过后在恢复扩大免疫接种规划以实现世卫组织2030年预定目标方面出现延误或行动缓慢，那么，在2020年至2030年期间出生的儿童中，预计将新增530万例慢性乙肝病毒感染，这些儿童此后死于乙肝病毒人数将新增100万人。所以，如果现在错失预防乙肝病毒新发感染的机会，将造成持久的和影响生命的后果。COVID-19可能会阻碍在消除乙肝病毒方面的进展。根据伦敦帝国学院与世卫组织合作开展的一项新的模拟研究，这一大流行病扰乱了乙型肝炎疫苗接种规划，可能会严重影响在实现全球战略目标方面的努力。
评论
当前我们可以看到，过去二十年来，在全球疫苗免疫联盟的大力支持下，全球推广乙型肝炎疫苗接种在公共卫生领域取得了巨大成就，儿童乙肝病毒感染率大幅下降。至2019年感染人数表明我们已实现可持续发展目标所确定的关于消除病毒性肝炎的一项重要具体目标。当然，预防乙肝病毒传染这一任务仍任重而道远。作为众多感染慢性乙型肝炎病毒群体中最脆弱的存在，儿童接种乙肝疫苗一直是当代热点。但仍需强调的是，预防乙型肝炎母婴传播和幼儿期传播是控制这一疾病和拯救生命的最重要战略。
撰稿：郑雅妮
翻译：段一鹏
编辑：招嘉艺
World Hepatitis Day: Accelerating the Elimination of Mother-to-child Hepatitis B Transmission
The proportion of children under five years of age chronically infected with hepatitis B (HBV) dropped to just under 1% in 2019 down from around 5% in the pre-vaccine era (the period between the 1980s and the early 2000s), according to new estimates from the World Health Organization (WHO).
Key words: World Health Organization, Accelerating the elimination of mother-to-child hepatitis B transmission, Health
This marks the achievement of one of the milestone targets to eliminate viral hepatitis in the Sustainable Development Goals ─ to reach under 1% prevalence of HBV infections in children under five years of age by 2020.
“No infant should grow up only to die of hepatitis B because they were not vaccinated ─ today’s milestone means that we have dramatically reduced the number of cases of liver damage and liver cancer in future generations,” said Dr Tedros Adhanom Ghebreyesus. “Preventing mother-to-child transmission of hepatitis B is the most important strategy for controlling the disease and saving lives. Even in the midst of the COVID-19 pandemic, we must ensure that mothers and newborns have access to life-saving services including hepatitis B vaccinations.”
On World Hepatitis Day 2020, WHO is calling for united and stepped-up action to build on this achievement through intensified efforts to prevent mother-to-child transmission of HBV through testing pregnant women and provision of antiviral prophylaxis to those who need it and maintaining and expanding access to hepatitis B immunization and birth dose vaccine.
Globally, more than 250 million people are living with chronic HBV infection. Infants are especially vulnerable: about 90% of children infected with HBV in their first year of life become chronic HBV carriers. HBV attacks the liver and claims the lives of nearly 900 000 people each year.
Preventing hepatitis B
Infants can be protected from HBV through a safe and effective vaccine that provides over 95% protection against infection. WHO recommends that all infants receive a first dose of the hepatitis B vaccine as soon as possible after birth – preferably within 24 hours – followed by at least 2 additional doses.
The scale-up of hepatitis B vaccine worldwide over the last two decades, which has been in large part due to the support provided by Gavi, the Vaccine Alliance, has been a great public health success story and contributed to the decrease in HBV infections among children. In 2019, coverage of 3 doses of the hepatitis B vaccine during childhood reached 85% worldwide, up from around 30% in 2000. However, access to the first critical dose within 24 hours of birth remains uneven. Global coverage of this birth dose is 43%, but this drops to 34% in the WHO Eastern Mediterranean Region and only 6% in the WHO African Region.
“Expanding access to a timely birth dose of the hepatitis B vaccine is the cornerstone of efforts to prevent mother-to-children transmission of HBV. For countries especially in regions such as sub-Saharan Africa, where the birth dose of hepatitis B vaccine has not yet been introduced, it is a priority to assure that protection as early as possible,” said Dr Meg Doherty, Director of Global HIV, Hepatitis and STI Programmes.
An additional way to protect children is to provide pregnant women with antiviral treatment to reduce mother-to-child transmission of HBV. WHO already recommends routine testing of all pregnant women for HBV, as well as HIV and syphilis as early as possible in their pregnancy. In view of new evidence on the safety and efficacy of antiviral prophylaxis in pregnant women and their children, WHO is issuing today 2 new recommendations:
1.Pregnant women who test positive for hepatitis B infection and have a high level of HBV in the blood (known as HBV viral load) should receive preventive antiviral therapy with tenofovir from the 28th week of pregnancy until birth. The antiviral drug, tenofovir is available at low cost in many countries of the world for less than US$3 per month.
2.In settings where HBV viral load testing is not available, WHO recommends the use of an alternative low cost test (HBeAg) to determine whether a woman is eligible for preventive antiviral therapy.
In countries that have already achieved high coverage of hepatitis B immunization, including timely birth dose, routine testing for HBV infection among pregnant women and antiviral prophylaxis for those in need is an additional opportunity to prevent onward transmission from mother to child.
Eliminating mother-to-child transmission of HBV is also an important stepping stone for reaching the targets of WHO’s global hepatitis strategy, which aims to reduce new hepatitis infections by 90% and deaths by 65%, compared to 2015 levels.
“Stopping vertical transmission of HBV is a key pillar of the global ‘triple elimination’ initiative, which seeks to eliminate mother-to-child transmission of three infections that are prevalent in low- and middle-income countries: HIV, syphilis and hepatitis B virus,” added Dr Doherty.
The COVID-19 pandemic jeopardizes future progress
COVID-19 threatens to hamper progress in eliminating HBV. According to a new modelling study conducted by Imperial College London in collaboration with WHO, disruptions to the hepatitis B vaccination programme due to the pandemic could have a serious impact on efforts to reach the targets of the global strategy.
Under a worst-case scenario, with high levels of disruptions of both the birth dose and childhood HBV immunization (by 60% and 20% for one year respectively), as well as a delay and slow recovery in the expansion of the vaccination programme towards the planned 2030 WHO-targets in the post COVID-19 period, there would be a projected 5.3 million additional chronic HBV infections among children born between 2020 and 2030 and 1 million additional HBV-related deaths among those children later on. Thus, missed opportunities now to prevent new HBV infections will have a long-lasting and life-impacting effect.
Comment
We have seen a tremendous public health achievement in promoting hepatitis B vaccination globally in the past twenty years, with the support of Gavi, the Vaccine Alliance. Hepatitis B infection rates among children significantly reduced as well. The infection rate in 2019 has shown the achievement of a milestone set in the Sustainable Development Goals regarding the elimination of viral hepatitis. Nonetheless, there is still much work to be done to prevent hepatitis B transmission. As the most vulnerable group to be chronically infected with hepatitis B, hepatitis vaccination for children has always been a hot issue. It should be further emphasized that preventing mother-to-child transmission is the most important strategy for controlling illness and saving lives.
Writer: Yani Zheng
Translator: Yipeng Duan
Editor: Jiayi Zhao
