CoVID-19の特徴〜中国の72 314例の要約

高齢者の死亡率が高いことは連日報道されていますが、医療従事者の死亡率が高いことはあまり考察されていません。

(あくまで管理者の私見ですが)何らかの処置の際に、大量のウイルスを肺まで吸引してしまった人が多いことが原因なのかも知れません。

今のところ、一律休校という政策は愚策で、海外のように「1名でも感染者が出たら休校」の方が正しいと思います。

このままでは、不況→倒産→失業→自殺という死亡者が、CoVID-19の肺炎で死ぬ老人よりも多くなるかも知れません。

SARSのように半年で収束させられない場合は、高齢者だけの隔離政策の方が優れているかも知れません。

（以上は、管理者の私見です。2020年3月7日記載）

**********************************************

合計72 314例の記録のうち、

44 672例がCOVID-19の確定症例として分類され（62％;咽頭スワブサンプルのウイルス核酸検査結果陽性に基づく診断）、

16186例が疑わしい症例（22％ ;症状と暴露のみに基づく診断、現在のニーズを満たすには検査能力が不十分であるため検査は実施されなかった）、

10 567例が臨床診断症例（15％;この指定は湖北省でのみ使用されている;これらの症例では検査なしで 診断が行われたが、症状、暴露、およびコロナウイルス肺炎と一致する肺の画像に基づいて診断された）

889例が無症状の症例（1％;ウイルス核酸検査結果が陽性であるが、発熱、乾性咳などの典型的な症状がない 、疲労がある症例）である。

軽症が、81％

重症が、14％

危篤が、5％

＜重症度別の死亡率＞

全死亡率2.3％

80歳以上で、14.8％

70−79歳で、8.0％

危篤症例で、49.0%

＜感染した医療従事者＞

感染者全体の3.8％

武漢での感染が、63%

14.8％が重症

5名が死亡

ほとんどの患者は30〜79歳（87％）、1％は9歳以下、1％は10〜19歳、3％は80歳以上でした。

ほとんどの症例は湖北省で診断され（75％）、ほとんどが武漢に関連した曝露を報告した（86％、すなわち武漢の居住者または訪問者、または武漢の居住者または訪問者との密接な接触）。

ほとんどの症例は軽度に分類された（81％、すなわち、非肺炎および軽度肺炎）。

ただし、14％は重度でした（すなわち、呼吸困難、呼吸数30分以上、血中酸素飽和度93％以下、吸気酸素分圧に対する動脈酸素分圧<300、および/または24〜48時間以内に肺浸潤が50％以上に進行する。）、

および5％が危篤である（すなわち、呼吸不全、敗血症性ショック、および/または多臓器不全）

全体的な致死率（CFR）は2.3％でした（44 672人の確定患者のうち1023人が死亡）。

9歳以下のグループでは死亡は発生しませんでしたが、

70〜79歳の症例のCFRは8.0％、

80歳以上の症例のCFRは14.8％でした。

軽度および重度の症例では死亡は報告されていません。

重症例のCFRは49.0％でした。

CFRは持病を持つ患者で高く、心血管疾患で10.5％、糖尿病で7.3％、慢性呼吸器疾患で6.3％、高血圧で6.0％、がんで5.6％でした。

44 672人の症例のうち、合計1716人が医療従事者（3.8％）で、そのうち1080人が武漢（63％）で感染した。

全体として、医療従事者の間で確認された症例の14.8％は重症以上として分類され、5人の死亡が観察されました。

COVID-19は、わずか30日間で単一の都市から全国に急速に広がりました。特に武漢市と湖北省では、地理的拡大と症例数の突然の増加の両方の速さが、中国の健康と公衆衛生サービスを驚かせ、すぐに圧倒しました。流行曲線は、混合発生パターンである可能性のあるものを反映しており、初期のケースは継続的な共通ソースを示唆しており、Huanan Seafood Wholesale Marketで人畜共通感染の可能性があり、後のケースではウイルスが人から人へ伝染し始めたため伝播したソースを示唆しています。

現在のCOVID-19の発生は、以前の重症急性呼吸器症候群（SARS; 2002-2003）および中東呼吸器症候群（MERS; 2012-継続中）の発生と類似している部分と、異なる部分があります。

SARSは、中国広東省の市場で、コウモリからジャコウネコを介した新規コロナウイルスの人獣共通感染として始まりました。

MERSは、サウジアラビアでのコロナウイルス（コウモリからヒトコブラクダを経由する可能性が高い）の人畜共通感染症でした。

3つのウイルス感染はすべて発熱と咳を伴うことが多く、高齢者や基礎疾患に伴う臨床転帰が不良な下気道疾患を引き起こすことがよくあります。

感染の確認には、気道サンプル（咽頭スワブ）の核酸検査が必要ですが、症状、暴露、胸部画像に基づいて臨床診断が行われる場合があります。

特定の効果的な抗ウイルス療法が特定されていないため、患者の支持療法は通常、標準的プロトコルです。

世界保健機関（WHO）は、2003年7月5日にSARSの発生を宣言しました。

29か国で合計8096人のSARS症例と774人の死亡が報告され、全体のCFRは9.6％でした。

MERSはまだ含まれておらず、27か国で2494の確定症例と858の死亡を34.4％のCFRで占めています。

SARSとMERSのCFRの方がかなり高いにもかかわらず、COVID-19は、多数の症例のためにより多くの総死亡をもたらしました。

2020年2月18日現在、中国は72 528人の確定症例（世界全体の98.9％）と1870人の死亡（世界全体の99.8％）を報告しています。

これは、現在の粗CFR 2.6％に相当します。

ただし、COVID-19症例の総数は、軽度および無症候性の症例を特定およびカウントするのが本質的に困難であるため、より高い可能性があります。

さらに、中国でのCOVID-19の試験能力はまだ不十分であるため、疑わしく臨床的に診断された多くの症例はまだ分母に数えられていません。

CFRは不確実で、湖北省は2.9％で、湖北省外では0.4％でした。

CFRは依然として慎重に解釈する必要があり、さらなる研究が必要です。

SARSおよびMERSのほとんどの二次感染は、病院で発生しました。

この状況でもCOVID-19の感染が発生しています。2020年2月11日現在、医療従事者の間で3019人の症例が確認されています（うち1716人が確認され、5人が死亡）。

しかし、これはCOVID-19の主要な感染経路ではありません。

むしろ、密接な接触者の間でかなりの感染が発生しているようです。

現在までに、湖北省以外の20の省が1183件の症例クラスターを報告しており、そのうち88％に2〜4件の確定症例が含まれています。

注目すべきことに、これまでに文書化されたクラスターの64％は家族の家庭内にありました。

（2020年2月16日にWHO評価チームに対して行われた中国疾病管理予防センターのプレゼンテーション）

したがって、COVID-19はSARSおよびMERSよりも伝達性が高いようであり、COVID-19の生殖数（R0）の多くの推定値はすでに公開されていますが、正確なR0推定値を作成したり、ダイナミクスを評価するにはまだ早すぎます。この分野でもさらなる研究が必要です

2003年以降、中国政府は流行対応能力を向上させてきました。 これらの取り組みの一部は、COVID-19への対応で明らかです。

たとえば、2002-2003年のSARSアウトブレイクでは、中国がWHOにアウトブレイクを報告するまでに300件の症例と5人の死亡がすでに発生していました。

一方、COVID-19のアウトブレイクでは、WHOに通知された時点で、20例1月3日の時点で、27例の感染者のみで、死亡例はありませんでした。

WHO通知の時点から、SARS-CoVが特定されるまでに2か月が経過したのに対し、WHO通知の時点から2019-nCoVが特定されるまで、わずか1週間でした。

中国の毎年の旧正月休暇前のCOVID-19発生のタイミングは、中国が発生への対応方法を検討した際の重要な要素でした。文化的には、これは一年で最大かつ最も重要な休日です。人々が家族の家に戻ることが期待されており、これが混雑した飛行機、電車、バスでこの期間中に住民や訪問者によって行われた数十億人の旅行の理由です。

これが意味することは、各感染者が長期にわたって、長距離にわたって多くの密接な接触をすることを意味し、政府は迅速に行動する必要がありました。

ただし、政府の対応の速さだけでなく、その対応の大きさの点でも、差し迫った休日の旅行の行動に影響を及ぼす必要がありました。

標的化された抗ウイルス薬やワクチンなどの特定の治療および予防オプションがCOVID-19でまだ利用できないため、中国は伝統的な公衆衛生のアウトブレイク対応の戦術、隔離、検疫、社会的距離、コミュニティ封じ込めに焦点を合わせました。

COVID-19の特定された症例患者は、既存の病院の指定された病棟ですぐに隔離され、武漢と湖北の増加する症例を隔離し、ケアするために2つの新しい病院が迅速に建設されました。 COVID-19症例と接触していた人々は、自宅で自分自身を検疫するか、症状の発症を監視できる特別な検疫施設に連れて行かれました。

すべての旧正月のお祝いを含む膨大な数の大規模な集まりがキャンセルされ、武漢と湖北省の都市の交通は制限され、厳重に監視されました。実質的にすべての輸送はその後、国家レベルで制限されました。

これらの手段はすべて、社会的距離を置くために制定されました。

さらに、武漢と湖北省内の他の15の周辺都市の推定4,000万から6,000万人の住民が、コミュニティ封じ込め措置の対象となりました。

これらのタイプの従来のアウトブレイク対応アクションは過去に何度も使用されてきましたが、そのような大規模で実行されたことはありません。

これらのアクションがアウトブレイクに対する合理的かつ比例的な応答であるかどうかについていくつかの質問がありました。

これらのアプローチの多くは市民の市民的自由を侵害する可能性があると主張する人もいれば、これらの措置の一部は「厳しい」と呼ばれています。

ただし、考慮する必要があるのは個人の権利だけではありません。

感染していないが感染のリスクがある人の権利も考慮しなければなりません。

これらのアプローチが効果的であったか（例：感染症の減少と死亡の回避）、およびこれらの潜在的な利点がコスト（例：経済的損失）を上回っているかどうかは、今後、時間を掛けて議論される必要があります。

February 24, 2020

Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China

Summary of a Report of 72 314 Cases From the Chinese Center for Disease Control and Prevention

Zunyou Wu, MD, PhD ; Jennifer M. McGoogan, PhD

JAMA. Published online February 24, 2020. doi:10.1001/jama.2020.2648

https://jamanetwork.com/journals/jama/fullarticle/2762130?fbclid=IwAR0jnVYOgTrZE11twucHo0ZD6ffpqV8rRB28gDq42S6wzM9UsAoCqI_n92A

The Chinese Center for Disease Control and Prevention recently published the largest case series to date of coronavirus disease 2019 (COVID-19) in mainland China (72 314 cases, updated through February 11, 2020).¹ This Viewpoint summarizes key findings from this report and discusses emerging understanding of and lessons from the COVID-19 epidemic.

Epidemiologic Characteristics of the COVID-19 Outbreak

Among a total of 72 314 case records (Box), 44 672 were classified as confirmed cases of COVID-19 (62%; diagnosis based on positive viral nucleic acid test result on throat swab samples), 16 186 as suspected cases (22%; diagnosis based on symptoms and exposures only, no test was performed because testing capacity is insufficient to meet current needs), 10 567 as clinically diagnosed cases (15%; this designation is being used in Hubei Province only; in these cases, no test was performed but diagnosis was made based on symptoms, exposures, and presence of lung imaging features consistent with coronavirus pneumonia), and 889 as asymptomatic cases (1%; diagnosis by positive viral nucleic acid test result but lacking typical symptoms including fever, dry cough, and fatigue).

Box.

Key Findings From the Chinese Center for Disease Control and Prevention Report

• 72 314 Cases (as of February 11, 2020)

  • Confirmed cases: 44 672 (62%)

  • Suspected cases: 16 186 (22%)

  • Diagnosed cases: 10 567 (15%)

  • Asymptomatic cases: 889 (1%)

• Age distribution (N = 44 672)

  • ≥80 years: 3% (1408 cases)

  • 30-79 years: 87% (38 680 cases)

  • 20-29 years: 8% (3619 cases)

  • 10-19 years: 1% (549 cases)

  • <10 years: 1% (416 cases)

• Spectrum of disease (N = 44 415)

  • Mild: 81% (36 160 cases)

  • Severe: 14% (6168 cases)

  • Critical: 5% (2087 cases)

• Case-fatality rate

  • 2.3% (1023 of 44 672 confirmed cases)

  • 14.8% in patients aged ≥80 years (208 of 1408)

  • 8.0% in patients aged 70-79 years (312 of 3918)

  • 49.0% in critical cases (1023 of 2087)

• Health care personnel infected

  • 3.8% (1716 of 44 672)

  • 63% in Wuhan (1080 of 1716)

  • 14.8% cases classified as severe or critical (247 of 1668)

  • 5 deaths

Most case patients were 30 to 79 years of age (87%), 1% were aged 9 years or younger, 1% were aged 10 to 19 years, and 3% were age 80 years or older. Most cases were diagnosed in Hubei Province (75%) and most reported Wuhan-related exposures (86%; ie, Wuhan resident or visitor or close contact with Wuhan resident or visitor). Most cases were classified as mild (81%; ie, nonpneumonia and mild pneumonia). However, 14% were severe (ie, dyspnea, respiratory frequency ≥30/min, blood oxygen saturation ≤93%, partial pressure of arterial oxygen to fraction of inspired oxygen ratio <300, and/or lung infiltrates >50% within 24 to 48 hours), and 5% were critical (ie, respiratory failure, septic shock, and/or multiple organ dysfunction or failure) (Box).¹

The overall case-fatality rate (CFR) was 2.3% (1023 deaths among 44 672 confirmed cases). No deaths occurred in the group aged 9 years and younger, but cases in those aged 70 to 79 years had an 8.0% CFR and cases in those aged 80 years and older had a 14.8% CFR. No deaths were reported among mild and severe cases. The CFR was 49.0% among critical cases. CFR was elevated among those with preexisting comorbid conditions—10.5% for cardiovascular disease, 7.3% for diabetes, 6.3% for chronic respiratory disease, 6.0% for hypertension, and 5.6% for cancer. Among the 44 672 cases, a total of 1716 were health workers (3.8%), 1080 of whom were in Wuhan (63%). Overall, 14.8% of confirmed cases among health workers were classified as severe or critical and 5 deaths were observed.¹

COVID-19 rapidly spread from a single city to the entire country in just 30 days. The sheer speed of both the geographical expansion and the sudden increase in numbers of cases surprised and quickly overwhelmed health and public health services in China, particularly in Wuhan City and Hubei Province. Epidemic curves reflect what may be a mixed outbreak pattern, with early cases suggestive of a continuous common source, potentially zoonotic spillover at Huanan Seafood Wholesale Market, and later cases suggestive of a propagated source as the virus began to be transmitted from person to person (Figure 1).¹

Epidemic Curve of the Confirmed Cases of Coronavirus Disease 2019 (COVID-19)

Daily numbers of confirmed cases are plotted by date of onset of symptoms (blue) and by date of diagnosis (orange). Because, on retrospective investigation, so few cases experienced illness in December, these cases are shown in the inset. The difference between the cases by date of symptom onset curve (blue) and the cases by date of diagnosis curve (orange) illustrates lag time between the start of illness and diagnosis of COVID-19 by viral nucleic acid testing. The graph's x-axis (dates from December 8, 2019, to February 11, 2020) is also used as a timeline of major milestones in the epidemic response. The first few cases of pneumonia of unknown etiology are shown in blue boxes on December 26 (n = 4) and 28-29 (n = 3). Most other cases that experienced onset of symptoms in December were only discovered when retrospectively investigated. Major epidemic response actions taken by the Chinese government are shown in brown boxes. The normally scheduled Lunar New Year national holiday is shown in light yellow, whereas the extended holiday during which attendance at school and work was prohibited (except for critical personnel such as health workers and police) is shown in dark yellow. This figure was adapted with permission.¹ CDC indicates Chinese Center for Disease Control and Prevention; HICWM, Hubei Integrated Chinese and Western Medicine; 2019-nCoV, 2019 novel coronavirus; WHO, World Health Organization.

Comparison of COVID-19 With SARS and MERS

The current COVID-19 outbreak is both similar and different to the prior severe acute respiratory syndrome (SARS; 2002-2003) and Middle East respiratory syndrome (MERS; 2012-ongoing) outbreaks. SARS was initiated by zoonotic transmission of a novel coronavirus (likely from bats via palm civets) in markets in Guangdong Province, China. MERS was also traced to zoonotic transmission of a novel coronavirus (likely from bats via dromedary camels) in Saudi Arabia. All 3 viral infections commonly present with fever and cough, which frequently lead to lower respiratory tract disease with poor clinical outcomes associated with older age and underlying health conditions. Confirmation of infection requires nucleic acid testing of respiratory tract samples (eg, throat swabs), but clinical diagnosis may be made based on symptoms, exposures, and chest imaging. Supportive care for patients is typically the standard protocol because no specific effective antiviral therapies have been identified.

The World Health Organization (WHO) declared the SARS outbreak contained on July 5, 2003. A total of 8096 SARS cases and 774 deaths across 29 countries were reported for an overall CFR of 9.6%. MERS is still not contained and is thus far responsible for 2494 confirmed cases and 858 deaths across 27 countries for a CFR of 34.4%. Despite much higher CFRs for SARS and MERS, COVID-19 has led to more total deaths due to the large number of cases. As of the end of February 18, 2020, China has reported 72 528 confirmed cases (98.9% of the global total) and 1870 deaths (99.8% of the global total). This translates to a current crude CFR of 2.6%. However, the total number of COVID-19 cases is likely higher due to inherent difficulties in identifying and counting mild and asymptomatic cases. Furthermore, the still-insufficient testing capacity for COVID-19 in China means that many suspected and clinically diagnosed cases are not yet counted in the denominator.² This uncertainty in the CFR may be reflected by the important difference between the CFR in Hubei (2.9%) compared with outside Hubei (0.4%).^1,2 Nevertheless, all CFRs still need to be interpreted with caution and more research is required.

Most secondary transmission of SARS and MERS occurred in the hospital setting. Transmission of COVID-19 is occurring in this context as well—3019 cases have been observed among health workers as of February 11, 2020 (of whom there have been 1716 confirmed cases and 5 deaths).¹ However, this is not a major means of COVID-19 spread. Rather, it appears that considerable transmission is occurring among close contacts. To date, 20 provinces outside of Hubei have reported 1183 case clusters, 88% of which contained 2 to 4 confirmed cases. Of note, 64% of clusters documented thus far have been within familial households (Chinese Center for Disease Control and Prevention presentation made to the WHO Assessment Team on February 16, 2020). Thus, although COVID-19 seems to be more transmissible than SARS and MERS, and many estimates of the COVID-19 reproductive number (R₀) have already been published, it is still too soon to develop an accurate R₀ estimate or to assess the dynamics of transmission. More research is needed in this area as well.

Response to the COVID-19 Epidemic

Since 2003, the Chinese government has improved its epidemic response capacity. Some of these efforts are evident in the response to COVID-19 (Figure 2). For example, in the 2002-2003 SARS outbreak, 300 cases and 5 deaths already had occurred by the time China reported the outbreak to the WHO, whereas in the COVID-19 outbreak, only 27 cases and zero deaths had occurred when the WHO was notified (January 3, 2020) (Figure 2). From the time of WHO notification, 2 months elapsed before SARS-CoV was identified compared with only 1 week from the time of WHO notification until 2019-nCoV was identified.

Timeline Comparing the Severe Acute Respiratory Syndrome (SARS) and Coronavirus Disease 2019 (COVID-19) Outbreaks

The timeline of events for the SARS outbreak (left) from first case to final worldwide containment. The timeline of events for the COVID-19 outbreak (right) from the onset of symptoms for the first case on December 8, 2019, to status on February 20, 2020. Over the course of the first 2 months, more than 70 000 cases have been confirmed and many more are suspected. WHO indicates World Health Organization.

^aIdentified later retrospectively.

The timing of the COVID-19 outbreak, prior to China’s annual Lunar New Year holiday, was an important factor as China considered how to respond to the outbreak. Culturally, this is the largest and most important holiday of the year. It is the expectation that people return to their family homes, which is the cause for the several billion person-trips made by residents and visitors during this time, mostly on crowded planes, trains, and buses. Knowing this meant each infected person could have numerous close contacts over a protracted time and across long distances, the government needed to quickly act. However, it was not only the speed of the government’s response, but also the magnitude of that response that were influenced by the impending holiday travel time. Knowing that specific treatment and prevention options, such as targeted antiviral drugs and vaccines, were not yet available for COVID-19, China focused on traditional public health outbreak response tactics—isolation, quarantine, social distancing, and community containment.^3-5

Identified case patients with COVID-19 were immediately isolated in designated wards in existing hospitals, and 2 new hospitals were rapidly built to isolate and care for the increasing numbers of cases in Wuhan and Hubei. People who had been in contact with COVID-19 cases were asked to quarantine themselves at home or were taken to special quarantine facilities, where they could be monitored for onset of symptoms. Enormous numbers of large gatherings were canceled, including all Lunar New Year celebrations, and traffic in Wuhan and in cities across Hubei was restricted and closely monitored. Virtually all transportation was subsequently restricted at a national level. All of these measures were instituted to achieve social distancing. In addition, an estimated 40 million to 60 million residents of Wuhan and 15 other surrounding cities within Hubei Province were subjected to community containment measures. Although these types of traditional outbreak response actions have been successfully used in the past, they have never been executed on such a large scale.

There have been some questions about whether these actions are reasonable and proportional responses to the outbreak. Some have argued that a number of these approaches may infringe on the civil liberties of citizens, and some of these measures have been referred to as “draconian.” However, it is not only individual rights that must be considered. The rights of those who are not infected, but at risk of infection, must be considered as well. Whether these approaches have been effective (eg, in terms of reduced infections and deaths averted), and whether these potential benefits have outweighed the costs (eg, economic losses), will be debated for years.^4,5

Next Steps

Importantly, another major goal of China’s current outbreak response activities is to help “buy time” for science to catch up before COVID-19 becomes too widespread. China must now focus on adjusting tactics and strategies as new evidence becomes available.^3,6 Much remains to be done and many questions remain unanswered. China is very grateful for the help it is receiving from the international scientific, health, and public health communities. The global society is more interconnected than ever, and emerging pathogens do not respect geopolitical boundaries. Proactive investment in public health infrastructure and capacity is crucial to effectively respond to epidemics like COVID-19, and it is critical to continue to improve international surveillance, cooperation, coordination, and communication about this major outbreak and to be even better prepared to respond to future new public health threats.