如果取消嚴格的COVID清零政策，中國能否避免一波死亡潮？
為更多老年人接種疫苗、儲備抗病毒藥物和擴大醫院設施將有助於緩解從COVID 清零的過渡。
資料來源：2022 年 11 月 30 日/2022 年 12 月 1 日更新/自然
北京的示威者舉著空白標語抗議 COVID-19 限制。圖片來源：Bloomberg via Getty
在全國罕見地表現出異議之後，中國正顯示出放鬆其嚴格的COVID 清零政策的跡象。 最近幾週，人們抗議政府透過嚴格封鎖、大規模檢測、隔離和旅行限制來平息疫情的政策——這些措施的經濟成本越來越高。 據新聞報導，過去幾天，幾個城市放鬆了限制，中國副總理孫春蘭表示將採取更寬鬆的方式來遏制病毒。 但結束清零 COVID 將帶來挑戰。 由於這項政策，中國祇有一小部分人接觸過 SARS-CoV-2，這種病毒會導致 COVID-19。 與此同時，疫苗的免疫力可能已經減弱，而加強劑更難銷售。 如果國家結束其嚴格的COVID 清零政策，它如何避免死亡和嚴重疾病的浪潮？
11 月病例的死灰復燃導致 11 月 29 日的每日記錄病例達到 71,000 例，創歷史新高。 廣州中山大學傳染病流行病學家盧家海說，這種熱潮主要是由 BF.7 Omicron 亞變體推動的。 模型研究顯示，如果中國現在取消嚴格限制，Omicron 可能會感染 1.6 億至 2.8 億人——導致約 130 萬至 210 萬人死亡，其中大部分是未接種疫苗的老年人。
根據 5 月 1 日發表在《自然醫學》(Nature Medicine) 上的一項研究，根據 3 月份的疫苗接種率，在疫情高峰期，對重症監護病床的需求可能是目前容量的 15 倍以上。 香港大學的流行病學家本·考林 (Ben Cowling) 說，疫苗覆蓋率現在更高了，但還不足以防止醫院不堪重負。「會有很多嚴重的病例和死亡」。
然而，研究人員表示，在從COVID 清零轉變時，有一些方法可以最大限度地減少嚴重疾病和死亡。 康乃迪覺克州紐黑文市耶魯大學研究中國公共衛生系統的經濟學家 Xi Chen 表示，首要任務應該是加強對老年人的加強疫苗接種，他們罹患嚴重疾病的風險更高。
增加疫苗接種
大多數中國人都接種了由 Sinovac 或國有企業 Sinopharm 生產的滅活病毒疫苗，這兩家公司都位於北京。 世界衛生組織建議為 60 歲及以上的人提供三劑方案，因為兩劑不太可能提供足夠的預防嚴重疾病的保護。 根據《自然醫學》的研究，如果中國向所有符合條件的 60 歲或以上的成年人接種第三劑疫苗，則可以將死亡人數減少 61%。
但到目前為止，該年齡段的人中只有 69%——80 歲或以上的人中只有 40%——接種了第三劑疫苗。「當大力推動清零 COVID 時，疫苗接種就退居次要地位」，考林說。 本週，政府宣布了一項增加老年人疫苗接種的計畫，包括將第二劑和第三劑之間的時間從六個月縮短到三個月。 陳說，激勵人們接種第三劑疫苗的一種方法可能是放寬對接種疫苗者的限制，例如讓他們進入公共場所。
9 月，中國批准了天津 CanSino Biologics 生產的可吸入型病毒載體疫苗； 該版本現在可供居住在一些大城市的居民使用。 研究人員仍在等待有關療效的後期臨床試驗數據，但希望吸入疫苗將有助於阻止病毒傳播，而不僅僅是預防嚴重疾病。「這對中國來說絕對是一個理想的場景，因為用這種疫苗進行大規模接種將使他們能夠在沒有退出浪潮的情況下退出 COVID-19」，考林說。
中國製造商還在對 Omicron 特異性疫苗和使用 mRNA 技術的疫苗進行後期臨床試驗。 研究人員表示，這些疫苗可以提供比目前在中國使用的疫苗更好的保護。
盧說，另一個重要戰略是儲備抗病毒藥物、培訓更多醫務人員和增加病床數量。 Nature Medicine 的研究顯示，透過使用抗病毒藥物 Paxlovid 治療所有出現 COVID-19 症狀的人，中國可以將死亡人數減少 89%。
放鬆隔離
目前在中國，感染 COVID-19 的人及其密切接觸者通常必須在指定的設施中隔離。 Chen 說，從COVID清零過渡意味著允許密切接觸者和患有輕度疾病或沒有症狀的感染者在家中照顧自己。「這將釋放大量資源，專注於治療弱勢群體」。
Cowling 說，還需要一種更務實的隔離方法，例如如果密切接觸者在快速抗原檢測中呈陰性，則允許他們工作。這將有助於確保醫療保健服務繼續發揮作用。陳說，政府還需要改變其公共信息的基調，以減輕圍繞 COVID-19 的恐慌、恐懼和恥辱感。 Chen 說，清零 COVID 從長遠來看是不可持續的」。
doi: https://doi.org/10.1038/d41586-022-04235-w
更新和更正
• 2022 年 12 月 1 日更新：這個故事已經更新，以反映有關中國已表示其清零 COVID 政策發生變化的消息。
參考文獻： Cai, J. et al. 《自然醫學》28、1468–1475（2022 年）。
Can China avoid a wave of deaths if it lifts strict zero COVID policy?
Vaccinating more older people, stocking up on antiviral drugs and expanding hospital facilities would help to ease the transition away from zero COVID.
NEWS EXPLAINER / 30 November 2022 / Update 01 December 2022 / Nature
Demonstrators in Beijing hold blank signs to protest against COVID-19 restrictions.Credit: Bloomberg via Getty
China is showing signs of easing its strict zero-COVID policy after rare displays of dissent across the country. In recent weeks, people have protested against the government’s policy of quashing outbreaks through strict lockdowns, mass testing, quarantining and travel restrictions — which comes at an increasing economic cost. In the past few days, several cities have loosened restrictions, and China’s vice-premier, Sun Chunlan, signalled a more permissive approach to containing the virus, according to news reports. But ending zero COVID would bring challenges. Thanks to the policy, only a small proportion of people in China have been exposed to SARS-CoV-2, the virus that causes COVID-19. Meanwhile, immunity from vaccines is likely to have waned, and boosters have been a harder sell. If the country ends its strict zero-COVID policy, how can it avoid a wave of deaths and severe disease?
A resurgence of cases in November has led to an all-time pandemic high that hit 71,000 daily recorded cases on 29 November. This upsurge has been driven largely by the BF.7 Omicron subvariant, says Lu Jiahai, an infectious-diseases epidemiologist at Sun Yat-sen University in Guangzhou. Modelling studies suggest that if China were to lift strict restrictions now, Omicron could infect between 160 million and 280 million people — resulting in some 1.3 million to 2.1 million deaths, largely among unvaccinated older adults.
At the outbreak’s peak, demand for intensive-care beds could be more than 15 times the current capacity, according to one study published in Nature Medicine in May1, based on vaccination rates in March. Vaccine coverage is higher now, but not enough to prevent hospitals being overwhelmed, says Ben Cowling, an epidemiologist at the University of Hong Kong. “There would be a lot of severe cases and mortality.”
However, researchers say there are ways to minimize severe disease and deaths when shifting away from zero COVID. One priority should be to ramp up booster vaccination for older people, who are at higher risk of developing severe disease, says Xi Chen, an economist at Yale University in New Haven, Connecticut, who studies China’s public-health system.
Increase vaccination
Most people in China have received an inactivated-virus vaccine made either by Sinovac or by the state-owned Sinopharm, both based in Beijing. The World Health Organization recommends these be given as a three-dose regimen for people aged 60 and older, because two doses are unlikely to provide enough protection against severe disease. According to the Nature Medicine study, China could reduce deaths by 61% if it gave a third dose to all eligible adults aged 60 or older.
But so far, just 69% of people in that age category — and only 40% of those aged 80 or older — have received a third dose. “When there is such a strong push for zero COVID, vaccination takes a back seat,” says Cowling. This week, the government announced a plan to increase vaccination among older people, including shortening the time between the second and third doses from six to three months. One way to incentivize people to get a third dose could be to loosen restrictions for those who do, such as giving them access to public spaces, says Chen.
In September, China approved an inhalable version of its viral-vector vaccine, made by CanSino Biologics in Tianjin; this version is now available to residents living in some large cities. Researchers are still waiting for late-stage clinical trial data on efficacy, but the hope is that inhaled vaccines will help to block viral spread, not just prevent severe disease. “That would be an absolute dream scenario for China because mass vaccination with such a vaccine would allow them to exit COVID-19 without an exit wave,” says Cowling.
Chinese manufacturers are also conducting late-stage clinical trials of Omicron-specific vaccines and ones that use mRNA technology. These could offer better protection than the vaccines that are currently used in China, say researchers.
Another important strategy is to stockpile antiviral drugs, train more medical staff and increase the number of hospital beds, says Lu. The Nature Medicine study suggests that China could reduce deaths by 89% by treating everyone who has COVID-19 symptoms with the antiviral drug Paxlovid.
Loosen quarantines
Right now in China, those infected with COVID-19, and their close contacts, typically have to quarantine in designated facilities. A transition away from zero COVID would mean allowing close contacts and infected people with mild disease, or no symptoms, to care for themselves at home, says Chen. “That will release large resources to focus on treating the vulnerable.”
A more pragmatic approach to quarantining is also needed, such as allowing close contacts to work if they test negative on a rapid antigen test, says Cowling. This would help to ensure that health-care services continue to function. The government would also need to change the tone of its public messaging to alleviate panic, fear and stigma around COVID-19, says Chen. Zero COVID “is unsustainable in the long run”, says Chen.
doi: https://doi.org/10.1038/d41586-022-04235-w
UPDATES & CORRECTIONS
•Update 01 December 2022: This story has been updated to reflect news that China has signalled a change in its zero COVID policy.
References
1.Cai, J. et al. Nature Med. 28, 1468–1475 (2022).