模型預測，中國 COVID 浪潮可能導致 100 萬人死亡

提高疫苗接種率、廣泛使用口罩和重新實施一些行動限制可以減少死亡人數。

資料來源：Smriti Mallapaty/ 2022 年 12 月 20 日更新/自然/財團法人台灣紅絲帶基金會編譯

在政府取消許多限制後，中國的 COVID-19 感染正在上升。 圖片來源：Qilai Shen/Bloomberg/Getty

根據政府取消許多嚴格的「清零 COVID-19」措施以來的一些初步預測，未來幾個月中國可能有多達 100 萬人死於 COVID-19。

「毫無疑問，中國將經歷糟糕的幾個月」，澳大利亞雪梨新南威爾斯大學傳染病模型專家詹姆斯.伍德說。

然而，兩項研究發現，透過給大多數人接種第四劑疫苗，同時高度堅持戴口罩和在死亡率激增時重新對社交互動施加臨時限制，可以減少死亡人數。 這些措施也可以減輕醫院的負擔。

「讓曲線變平永遠都不晚」，研究中國公共衛生系統的耶魯大學經濟學家陳曦說。

在過去的一個月裡，中國政府取消了許多為遏制病毒傳播而實施的限制措施。 它結束了對整個城市的大規模封鎖，取消了對區域內和區域間旅行的限制，並允許感染 SARS-CoV-2 的人在家中隔離，而不是在集中設施中隔離。 在重慶，輕症或無症狀的感染者甚至可以上班。 檢測現在是自願的，上週，國家衛健委宣布將停止報告無症狀感染者人數。

官方數據顯示，自11月下旬以來，由於檢測要求的變化，報告病例數一直在下降，但有跡象顯示，部分地區的感染病例迅速上升。 事實上，根據 12 月 16 日在 medRxiv 上發布的未經同行評審的北京市傳播分析，北京的感染可能已經達到頂峰。

第四劑

其中一項模型研究於 12 月 14 日作為預印本發布，未經同行評審，使用今年早些時候在香港和上海爆發的數據來比較中國的不同情況。 研究發現，由於最近放寬了限制，如果感染人數像預期的那樣迅速增加，醫院將不堪重負。 研究預測，這可能會在未來幾個月內導致約 100 萬人死亡。

但是，澳大利亞珀斯 Telethon 兒童研究所的建模師 Ewan Cameron 說，這些估計僅包括直接因 COVID-19 造成的死亡，並沒有考慮因延遲治療非 COVID-19 疾病患者而導致的額外死亡 .

該研究顯示，如果 85% 的人口接種第四劑疫苗而不是該國大多數人接種的滅活病毒疫苗，它可能會減緩感染的上升並減少嚴重感染和死亡的人數。 推進第四劑疫苗，同時向大多數 60 歲及以上的人以及其他罹患嚴重疾病的高風險人群提供抗病毒藥物，可以將死亡人數減少高達 35%。

澳大利亞墨爾本莫納什大學傳染病模型專家 James Trauer 表示：「在重大流行病爆發前夕，實現盡可能高的疫苗接種覆蓋率對中國來說非常重要」。 他還指出，關於疫情造成的死亡人數和減緩傳播措施的影響的預測仍然存在很多不確定性。

12 月 13 日，政府宣布 60 歲及以上的人和其他高危人群應該接種第四劑疫苗，最好是基於與第一劑不同技術的疫苗。 但在中國60歲以上的2.6億多人口中，只有70%的60歲以上和40%的80歲以上接種了第三劑。

伍德指出，中國要從第四劑疫苗的病毒減緩作用中獲益可能已經太晚了，因為現在許多限制已經解除，傳播已經很廣泛。 他還「不相信額外劑量會對傳播產生重大影響」，因為循環的 Omicron 病毒變異株顯示出逃避人體免疫反應的強大能力。

死亡人數減少

另一個模型估計，如果中國繼續目前的道路，到明年 4 月，中國將面臨 50 萬人因 COVID-19 死亡，到 2023 年底將有 160 萬人死亡。 該模型追踪和預測 COVID-19 的全球負擔，並由西雅圖華盛頓大學健康指標與評估研究所定期開發和更新。 該研究所的流行病學家 Ali Mokdad 說，到 3 月底，中國的死亡人數可能會上升到每天近 9,000 人。

該模型預測，如果中國在死亡率超過某個閾值時採取某些措施，從現在到 4 月，死亡總人數可能會減少到 29 萬左右。 這些包括重新實施限制、第三劑和第四劑疫苗的高接種率以及對高危人群的高抗病毒藥物治療。 廣泛使用口罩可以將死亡人數進一步減少到 230,000 人左右。 Mokdad 說，在中國，人們對戴口罩的順從性很高，放寬的限制導致人們選擇限制行動的行為發生了變化。「他們不會[讓它]撕裂」。

Cameron 說，這兩項研究在死亡率估計和介入措施的影響方面大體一致。「這種相似性在很大程度上反映了一種共識，只有在全國範圍內大規模且難以控制的傳播散播之後，才能實現群體免疫」。doi: https://doi.org/10.1038/d41586-022-04502-w

更新和更正

• 2022 年 12 月 20 日更新：本文已更新，包括北京的感染數據和重慶出台的政策信息。

參考文獻：

1. Leung, K. et al. medRxiv 預印本 https://doi.org/10.1101/2022.12.15.22283522 (2022)。

2. Leung, K., Leung, G.M. & Wu, J. T. medRxiv 預印本 https://doi.org/10.1101/2022.12.14.22283460 (2022)。

China COVID wave could kill one million people, models predict

Boosting vaccination rates, widespread mask use and reimposing some restrictions on movement could reduce the number of deaths.

Smriti Mallapaty/19 December 2022/Update 20 December 2022/Nature

COVID-19 infections are rising in China after the government lifted many restrictions. Credit: Qilai Shen/Bloomberg/Getty

Up to one million people in China could die from COVID-19 over the next few months, according to some of the first projections since the government lifted many of its strict ‘zero-COVID-19’ measures.

“There’s no doubt that China is in for a bad couple of months,” says James Wood, an infectious-disease modeller at the University of New South Wales in Sydney, Australia.

However, two studies find that the number of deaths could be reduced by giving most of the population a fourth vaccine dose, combined with a high level of adherence to masking and reimposition of temporary restrictions on social interactions when death rates surge. These measures could also ease the burden on hospitals.

“It is never too late to flatten the curve,” says Xi Chen, an economist at Yale University in New Haven, Connecticut, who studies China’s public-health system.

Over the past month, the Chinese government has dismantled many of the restrictions it imposed to quash the virus’s spread. It has ended the mass lockdown of entire cities, lifted restrictions on travel within and between regions and allowed people infected with SARS-CoV-2 to isolate at home instead of in centralized facilities. In Chongqing, infected people with mild or no symptoms can even go to work. Testing is now voluntary, and last week, the National Health Commission announced that it will stop reporting the number of infected people who have no symptoms.

Officially, the number of reported cases has been dropping since late November because of the changes in testing requirements, but there are indications that infections in some regions have risen rapidly. In fact, infections in Beijing might have already peaked, according to an analysis of transmission in the city posted on medRxiv on 16 December without peer review.

Fourth doses

One of the modelling studies, posted as a preprint without peer review on 14 December, uses data from outbreaks in Hong Kong and Shanghai earlier this year to compare different scenarios in China. It finds that hospitals will be overwhelmed if infections rise as rapidly as expected because of the latest easing of restrictions. This will probably result in about one million deaths over the next few months, the study forecasts.

But these estimates include only deaths due directly to COVID-19, and do not take into account excess deaths because of delays in treating people with non-COVID-19 diseases, says Ewan Cameron, a modeller at the Telethon Kids Institute in Perth, Australia.

The study suggests that if 85% of the population gets a fourth dose of a vaccine other than the inactivated-virus vaccines most people in the country have received, it could slow the rise in infections and reduce the number of severe infections and deaths. Pushing fourth vaccine doses, combined with giving antiviral drugs to most people aged 60 and older and to other individuals at high risk of developing severe disease, could reduce deaths by up to 35%.

“It is really critical for China to achieve the highest vaccination coverage possible in the period immediately before the major epidemic takes off,” says James Trauer, an infectious-disease modeller at Monash University in Melbourne, Australia. He also notes that there is still a lot of uncertainty around the projections about the epidemic’s toll and the impact of measures to slow the spread.

On 13 December, the government announced that people aged 60 and older, and other high-risk groups, should get a fourth dose of vaccine, preferably one based on a different technology from their primary dose. But of the more than 260 million people in China older than 60, only 70% aged 60 and older, and only 40% aged 80 and more, have received a third dose.

Wood notes that it might already be too late for China to benefit from the virus-slowing effects of fourth doses because there is already widespread transmission now that many restrictions have been lifted. He is also “not convinced an extra dose will make a big difference to transmission”, because circulating Omicron variants of the virus show a strong ability to evade the body’s immune response.

Fewer deaths

Another model estimates that China will face a COVID-19 death toll of half a million people by April next year, with 1.6 million deaths by the end of 2023, if the country continues on its current path. The model tracks and forecasts the global burden of COVID-19, and is developed and updated regularly by the Institute for Health Metrics and Evaluation at the University of Washington, Seattle. Deaths in China could rise to close to 9,000 a day by the end of March, says Ali Mokdad, an epidemiologist at the institute.

The model forecasts that the total number of deaths could be reduced to around 290,000 between now and April if China brings in certain measures when the death rate passes a certain threshold. These involve reimposing restrictions, high rates of third- and fourth-dose vaccination and high antiviral drug treatment for at-risk groups. Widespread mask use could reduce deaths still further, to around 230,000. Adherence to masking is high in China, and the eased restrictions have led to changes in behaviour in which people are choosing to restrict their movement, says Mokdad. “They will not [let it] rip.”

The two studies broadly agree on mortality estimates and the impact of interventions, says Cameron. “This similarity in large part reflects an agreement that herd immunity will only be achieved after a large, and difficult to contain, spread of transmission throughout the entire country.”

doi: https://doi.org/10.1038/d41586-022-04502-w

UPDATES & CORRECTIONS

•Update 20 December 2022: This story has been updated to include data on infections in Beijing and information on a policy introduced in Chongqing.

References

1.Leung, K. et al. Preprint at medRxiv https://doi.org/10.1101/2022.12.15.22283522 (2022).

2.Leung, K., Leung, G. M. & Wu, J. T. Preprint at medRxiv https://doi.org/10.1101/2022.12.14.22283460 (2022).