mpox 大流行結束了嗎？
高收入國家的 mpox 病例數減少顯示疫情已得到控制，但對流行國家的支持仍然至關重要。
資料來源：http://www.thelancet.com/infection / 2023 年 2 月 23 日
塔爾哈·布爾基報導。 美國於 2022 年 8 月 4 日首次宣布 mpox（當時稱為猴痘）進入公共衛生緊急狀態。當時，該國每天報告 400 多例新病例。 「我們敦促每個美國人認真對待猴痘，並承擔起幫助我們應對這種病毒的責任」，美國衛生與公眾服務部部長澤維爾·貝塞拉 (Xavier Becerra) 在宣佈公共衛生緊急狀態時表示，顯示出他是在疫情最嚴重的時候發言。 自12月中旬以來，美國每天的mpox病例數一直是個位數。 美國疾病控制與預防中心 (CDC) 估計，該病毒的 R0 目前在 0·83–0·96 範圍內。 貝塞拉表示，一旦公共衛生緊急狀態在 2023 年 1 月底到期，將不再延續。
來自其他地方的消息同樣令人鼓舞。 從 2022 年 12 月 26 日到 2023 年 1 月 1 日，全球報告了 373 例 mpox 病例，低於前一周的 673 例。 截至 1 月 2 日，在持續爆發的 110 個受 mpox 影響的國家中，有 79 個國家在超過 21 天（該病的最長潛伏期）內未報告任何新病例。 在歐洲，疫情在7月達到頂峰。 從那時起，案件下降了 95% 以上。 英國於 2022 年 5 月首次發現了這種新興流行病，但數週以來都沒有記錄到任何新的 mpox 感染。 2022 年 1 月 1 日至 2023 年 1 月 1 日期間，全球有近 84,000 例 mpox 病例，其中包括以前未報告過該病的 103 個國家。 但只有 75 人死亡。
疫情集中在男男性行為者 (MSM) 中。 97% 的可用數據病例發生在男性中，大多數年齡在 18-44 歲之間。 在有性取向數據的案例中，84% 發生在 MSM 中。 關於 mpox 是否可以透過精液傳播的問題尚未確定，但該病毒肯定需要密切接觸。 2019 年的一項系統回顧得出的結論是，當 mpox 仍局限於西非和中非的流行地區時，由病人將病毒傳播給未接種疫苗的家庭接觸者的可能性約為 8%。
「這次mpox疫情的流行曲線基本反映了病毒的基本特徵； 人們早就知道 R0 不會超過 1，有針對性的公共衛生介入措施可以對傳播產生巨大影響」，亞伯達大學醫學微生物學和免疫學系病毒學家 David Evans 解釋說（ 艾德蒙頓，AB，加拿大）。
當 WHO 秘書長 Tedros Adhanom Ghebreyesus 於 2022 年 7 月宣布 mpox 為國際關注的突發公共衛生事件時，他強調「可以透過在正確的群體中採取正確的策略來阻止疫情」。 政策制定者將他的建議牢記在心。「政府和公共衛生當局的巨額投資給我留下了深刻的印象，這些投資允許採取多管齊下的應對措施，包括在風險溝通和社區參與方面的努力」，英國倫敦大學傳染病和國際衛生學院教授 Ali Zumla 說。
「在流行病開始時，政策制定者非常擔心如何在 mpox 上表達他們的訊息而不顯得恐同或使用帶有偏見的語言。 我認為他們做得非常好」，埃文斯說。 另一方面，在流行初期，一些人認為擔心同性戀恐懼症會延遲向風險最高的群體發送訊息，因此圍繞 mpox 完善溝通的策略引發了廣泛的爭論。 去年年底，世衛組織建議將“monkeypox”重新命名為“mpox”，因為擔心原來的名字會帶來污名化。 「猴痘」一詞將在 2023 年 11 月底前逐步淘汰； 到那時，這兩個名稱將互換使用。
Demetre Daskalakis 是美國國家 mpox 應對工作的副協調員。 他強調了將社區參與置於疾病預防和控制工作最前沿的重要性。 「與男同性戀者和雙性戀者交流、與他們合作並讓他們告訴我們當建議人們暫時改變行為的最佳方式是什麼，這對我們來說至關重要，同時我們推出了疫苗並減少了傳播」， Daskalakis 告訴刺胳針傳染病期刊。 CDC 於 2022 年 8 月報告的一項針對 MSM 的調查發現，大約一半的受訪者減少了性伴侶的數量，同樣比例的受訪者減少了與透過約會應用軟體上認識的男性發生性關係。
美國通過改用皮內注射來擴大受限的疫苗供應，這只需要皮下接種所需劑量的五分之一。 在美國食品和藥物管理局緊急批准皮內注射後的兩周半內，該國 80% 的 mpox 疫苗劑量都是皮內注射的。 CDC 對 9,544 例 mpox 病例的研究計算出，未接種疫苗的人的疾病發病率幾乎是接種兩劑疫苗的人的 10 倍。 沒有證據顯示皮下注射疫苗和皮內注射疫苗之間的功效存在差異，儘管後者需要特別熟練的管理人員。
「如果知道我們可以提供 mpox 疫苗在感染多長時間後仍能看到保護效果，那將是一件好事； 這將使我們了解在新的疫情爆發後我們有什麼樣的機會窗口來啟動疫苗接種活動，以及我們是否可以考慮疫苗的治療用途，而不僅是預防用途」，埃文斯說。
美國幾個城市的疫苗接種車被引導到 MSM 聚集的地方，為場域內外的顧客和參加派對的人接種疫苗。「在 HIV/AIDS 流行期間，MSM 與公共衛生之間的關係如火如荼」，Daskalakis 指出。「即使當時你不在場，也有一種祖傳的記憶。 因此，當 mpox 進入社區時，人們已經準備好採取行動，為自己的健康負責。 我們與值得信賴的訊息傳遞者密切合作，他們幫助傳播了有關病毒和疫苗的訊息」。類似的努力在加拿大、愛爾蘭共和國和英國等國家的反應中得到了體現。 祖姆拉指出：「高危人群團結起來，聽從公共衛生指導，採取預防措施並調整行為改變，以限制病毒的傳播」。
儘管如此，祖姆拉警告說，還有很多工作要做。 「雖然歐洲和美國的大量資源的投資減少了 mpox 威脅，但它仍然是西非和中非的一個主要公共衛生問題，那裡控制它的資源缺稀」，他說。 「在發生動物與人之間傳播的地區，如果不為人類和最終動物提供疫苗，就不可能完全消滅猴痘病毒。 然而，儘管病毒可能再次從非洲傳播出去，但非洲大陸的公共衛生系統仍未得到所需的支持」。 直到 2022 年 11 月底，非洲才獲得第一批 mpox 疫苗。 Zumla 補充說：「我們需要看到非洲和歐洲的「健康一體」計畫 ( One-Health programmes ) 與公共衛生機構之間開展出真正的合作，從源頭上應對眾多新興和再浮現的公共衛生威脅，這樣我們才能防止流行病蔓延」。
塔哈爾.布爾基報導
The end of the mpox pandemic?
The decreased numbers of mpox cases in high-income countries indicates that the epidemic is under control but support to endemic countries remains crucial.
http://www.thelancet.com/infection / Vol 23 February 2023
Talha Burki reports. The USA first declared a public health emergency for mpox, which was then known as monkeypox, on Aug 4, 2022. At the time, the country was reporting over 400 new cases of the disease every day. “We urge every American to take monkeypox seriously and to take responsibility to help us tackle this virus”, stated US Department of Health and Human Services Secretary, Xavier Becerra, when he declared the public health emergency. It turned out that he was speaking at the height of the epidemic. Since mid-December, the number of daily cases of mpox in the USA has been in single digits. The US Centers for Disease Control and Prevention (CDC) estimate that the R0 for the virus is currently in the region of 0·83–0·96. Becerra has indicated that the public health emergency will not be renewed once it expires at the end of January 2023.
The news from elsewhere has been just as encouraging. From Dec 26, 2022, to Jan 1, 2023, 373 cases of mpox were reported globally, down from 673 for the previous week. As of Jan 2, 79 of the 110 countries that have been affected by mpox in the ongoing outbreak had not reported any new cases for over 21 days, the maximum incubation period for the disease. In Europe, the epidemic peaked in July. Since then, cases have fallen by well over 95%. The UK, where the emerging epidemic was first detected in May 2022, has not registered any new mpox infections for several weeks. There were almost 84 000 cases of mpox worldwide between Jan 1, 2022, and Jan 1, 2023, including in one hundred and three countries which had not previously reported the disease. But there were only 75 deaths.
The outbreak has been concentrated among men who have sex with men (MSM). 97% of the cases for which data are available have occurred in men, mostly aged 18–44 years. 84% of cases for which there are data on sexual orientation have been in MSM. The question as to whether mpox can be transmitted through semen has yet to be determined, but the virus certainly requires close contact. A systematic review from 2019, when mpox was still confined to the endemic regions of west and central Africa, concluded that the chances of someone passing on the virus to an unvaccinated household contact was somewhere in the region of 8%.
“The epidemic curve for this outbreak of mpox pretty much reflects the basic features of the virus; it has been long known that the R0 is not much more than 1, and that targeted public health interventions can have a dramatic effect on transmission”, explained David Evans, a virologist in the department of medical microbiology and immunology at the University of Alberta (Edmonton, AB, Canada).
When WHO director-general Tedros Adhanom Ghebreyesus declared mpox a public health emergency of international concern in July 2022, he emphasised that the outbreak “can be stopped with the right strategies in the right groups”. Policymakers have taken his advice to heart. “I have been very impressed by the huge investments by governments and public health authorities, which have allowed a multi-pronged response, including efforts in risk communication and community engagement”, said Ali Zumla, professor of infectious diseases and international health at University College London, UK.
“At the beginning of the epidemic, policymakers were very worried about how to phrase their messaging on mpox without appearing homophobic or using prejudiced language. I think they did really well”, said Evans. On the other hand, at the beginning of the epidemic some thought that worry about homophobia delayed messaging to the groups most at risk so strategies of perfecting communication around mpox were ground for extensive debate. Late last year, WHO recommended renaming ‘monkeypox’, ‘mpox’, in light of concerns that the original names was stigmatising. The term ‘monkeypox’ will be phased out by the end of November 2023; until then the two names will be used interchangeably.
Demetre Daskalakis is deputy coordinator of the national mpox response for the USA. He stressed the importance of placing community engagement at the forefront of disease prevention and control efforts. “It was vital for us to communicate with gay and bisexual men, to work with them, and have them let us know what the best way was to advise people on changing their behaviour temporarily, while we rolled out the vaccine and reduced transmission”, Daskalakis told The Lancet Infectious Diseases. A survey of MSM reported by the CDC in August 2022 found that roughly half of respondents had reduced their number of sexual partners, and a similar proportion had cut down on sex with men they met through dating apps.
The USA stretched the constrained vaccine supplies by switching to intradermal administration, which only requires a fifth of the dosage needed for subcutaneous vaccination. Within two and a half weeks of the US Food and Drug Administration’s emergency authorisation of intradermal injections, 80% of doses of the mpox vaccine in the country were being administered intradermally. A CDC study of 9,544 mpox cases calculated that incidence of the disease among unvaccinated individuals was almost 10 times higher than for those who had received two doses of the vaccine. There was no evidence of differing efficacy between the subcutaneous and intradermally injected vaccines, though the latter requires a particularly skilled administrator.
“It would be good to know how far into the infection we can provide the mpox vaccine and still see a protective effect; it would give us an idea of what kind of window of opportunity we have to kick off vaccination drives after a new outbreak, and whether we can think about therapeutic use of the vaccine, rather than prophylactic”, said Evans.
Vaccination vans in several American cities were directed to places where MSM gathered, vaccinating patrons and partygoers inside and outside the venue. “The relationship between MSM and public health was forged by fire, during the HIV/AIDS epidemic”, pointed out Daskalakis. “Even if you were not around at the time, there is still a kind of ancestral memory. So when mpox entered the community, people were ready to spring into action and take charge of their health. We worked closely with trusted messengers who helped get the word out about the virus and then the vaccine”. Similar efforts characterised the response in countries such as Canada, the Republic of Ireland, and the UK. “The high risk groups united, heeded public health guidance, took precautions, and adapted behaviour change so as to limit spread of the virus”, noted Zumla.
Nonetheless, Zumla cautioned that there is still much to be done. “Whilst the mpox threat has been reduced by massive resource investments in Europe and USA, it remains a major public health issue in west and central Africa, where resources to control it are scarce”, he said. “In areas where animal- to-human transmission occurs, it will be impossible to eliminate the monkeypox virus completely without a vaccine for people and eventually animals. Yet despite the risk that the virus might spread out of Africa again, public health systems in the continent are still not being given the support they need”. It was not until the end of November 2022 that Africa was able to secure its first batch of mpox vaccine. “We need to see truly collaborative work between African and European One-Health programmes and public health agencies to tackle the numerous emerging and re-emerging public health threats at their source, so we can prevent epidemic spread”, added Zumla.
Talha Burki