一些人擔心新型冠狀病毒爆發使中國經濟雪上加霜，會嚴重拖累2020年的中國與全球的增長率。但有幾個重要因素讓疫情對經濟增長的最終影響變得有限。
作者：魏尚進 中國金融四十人論壇（CF40）學術顧問、復旦大學泛海國際金融學院學術訪問教授、哥倫比亞大學終身講席教授
新型冠狀病毒（2019-nCoV）起源於中國第九大城市、國內主要交通樞紐武漢。它引起的恐慌使許多人想起2003年SARS危機高峰期的恐懼和不確定性。中國股市在上漲了幾個月後，最近幾日逆轉而下，全球其他股市也紛紛跟進跌勢。這可能反映出市場對疫情影響中國經濟及全球增長的擔憂。這些擔憂合理嗎？
我的基本預測是，新型冠狀病毒疫情在近期內會繼續惡化，感染和死亡病例數量可能在2月的第二或第三週達到頂峰。但我預計疫情將於4月初得到基本控制。
在此基準情況下，我的估算是，這一病毒對經濟的影響雖負但有限。它對中國2020年GDP增長率的影響可能很小，大約降低0.1個百分點。對2020年第一季度的增長影響較大，也許會使當季的年化增長率降低1個百分點，但這將被今年餘下時間裡高於趨勢的增長率大幅抵消。對全球GDP增長的影響將更小。
這種預測借鑑了2003年SARS危機的經歷。那場危機導致了2003年第二季度中國GDP增長大幅下滑，但隨後兩個季度的高速增長基本上抵消了這一頹勢。儘管2003年全年的經濟增長率約為10％，但當時許多投行經濟學家都高估了那場公共衛生危機對經濟的負面影響。如果從2000年至2006年的GDP年實際增長率的時間序列來看，很難從數據中看出SARS的影響。
一些人擔心這次疫情爆發時正值為期一週的農曆新年節慶伊始和傳統的寒假旅行之際，這將加劇其對經濟的負面影響，因為這個階段本該是購物、餐飲與旅遊的高峰但卻因為疫情而沒有發生。但是，這種講法或許忽略了三個重要因素。
首先，今天與SARS之時有一個很大的不同是中國已經進入了互聯網商業時代，消費者越來越多地在網上購物。新型冠狀病毒造成的線下銷售減少，大部分可能會被（快遞恢復後的）在線購物的增加所抵消。而且大部分當前取消的度假很可能會被未來的旅行所取代，因為經濟寬裕的家庭已經預留了旅行預算。
許多工廠本就安排在農曆新年假期中停產，因此疫情爆發的時機可能使進一步停工的必要性降到最低。同樣，許多政府機關和學校都按計劃本來就會在春節期間關閉。政府剛剛宣佈延長假期，但是許多公司會想盡辦法在以後彌補回損失的時間。因此，短期的負面影響很可能主要集中在餐飲、酒店和航空業。
其次，所有報告都表明，武漢冠狀病毒的致死率不如SARS（儘管它初期的傳播速度可能更快）。通過採取主動積極的措施，將確診和疑似患者與其他人群隔離開來，這也大大增強了更早遏制疫情的機會，進而增加了本季度損失的經濟產出將被今年剩餘時間增加的經濟活動抵消的可能性。
再者，中國貿易談判代表於1月15日完成了與美國簽署“第一階段”貿易協議。無論當時是否意識到武漢新型冠狀病毒的嚴重性，協議的簽署的節點是比較幸運的。通過大量增加從美國（及其他地區）進口口罩和醫療用品，中國可以同時應對公共衛生危機，並履行其在貿易協議下進口更多商品的承諾。
此次的新型冠狀病毒對其他經濟體的影響將更加有限。在過去的幾年中，許多主要經濟體中央銀行已經開發出模型來衡量中國經濟放緩對其經濟的影響。雖然這些模型的建立並非用來評估當前的公共衛生危機，但它們確實將各自經濟體與中國之間的貿易和金融聯繫納入考量。
根據經驗，中國GDP增長放緩對美國和歐洲經濟體的負面影響的百分比大約是其自身幅度的五分之一。若當前的新型冠狀病毒疫情使中國的經濟增長率降低了0.1個百分點，那麼美國和歐洲的經濟增長可能會下降約0.02個百分點。鑑於澳大利亞與中國在大宗商品貿易和旅遊業方面更為緊密的聯繫，這對澳大利的經濟增長的影響可能是兩倍，但經濟增長率下降0.04個百分點的幅度仍然很小。
這樣計算的假定是新型冠狀病毒不會廣泛傳播到這些國家並造成直接的破壞。鑑於中國以外的病例數量較少，目前看來不太可能出現這種情況。
當然，如果新型冠狀病毒危機的持續時間遠遠超過這一基準假設，它對中國和其他經濟體的影響可能會更加嚴重。即便在這種情況下，重要的是要記住，中國的決策者仍有貨幣和財政擴張的空間：與許多其他經濟體相比，中國的銀行準備金率相對較高，公共部門債務相對於GDP的比例仍然可控。通過在必要時用好這一政策空間，中國政府可以限制當前疫情危機對經濟的最終影響。
新型冠狀病毒的爆發在中國和世界其他地區引發警覺是可以理解的。但從經濟視角來看，現在恐慌還為時過早。█
Will the Coronavirus Cause a Major Growth Slowdown in China?
SHANG-JIN WEI
Some fear that China’s coronavirus outbreak will be a major drag on China’s and global growth rates. But three important factors may limit the virus’s impact.
The panic generated by the new coronavirus, 2019-nCoV, which originated in Wuhan, China’s ninth largest cities and a major domestic transport hub, reminds many of the fear and uncertainty at the peak of the 2003 SARS crisis. China’s stock market, after rising for months, has reversed itself in recent days, and global markets have followed suit, potentially reflecting concerns about the epidemic’s impact on the Chinese economy and global growth. Are these worries justified?
My baseline projection is that the coronavirus outbreak will get worse before it gets better, with infections and deaths possibly peaking in the second or third week of February. But I expect that the epidemic to be under control by early April.
Under this baseline scenario, my best estimate is that the virus will have only a limited negative economic impact. Its effect on Chinese GDP growth rate in 2020 is likely to be small, perhaps a reduction on the order of 1/10 of a one percentage point. The effect in the first quarter of 2020 will be big, perhaps lowering growth by one percentage point on an annualized basis, but this will be substantially offset by above-the-trend growth in the rest of the year. The impact on the world GDP growth will be even smaller.
Such a prediction is parallel to the experience of the 2003 SARS crisis. That crisis produced a big decline in China’s GDP growth in the second quarter of that year, which was then largely offset by higher growth in the subsequent two quarters. While the whole year growth rate in 2003 was about 10%, many investment bank economists at the time over-predicted the negative growth impact of the health crisis. If one looks at the time series of annual real GDP growth rates from 2000-2006, it will be very hard to see a SARS effect in the data.
Some fear that the epidemic’s timing – at the start of the week-long Chinese New Year celebration, and in the middle of traditional school-break travels – will exacerbate the economic fallout by keeping many people away from shops, restaurants, and travel hubs. But three important factors may limit the virus’s impact.
First, in contrast to the SARS outbreak, China is now in the Internet commerce age, with consumers increasingly doing their shopping online. Much of the reduction in offline sales owing to the virus will likely be offset by an increase in online purchases (after the resumption of the delivery service). And most of the vacations canceled today will probably be replaced by future trips, because better-off households have already set aside a holiday travel budget.
Many factories have scheduled production stoppages during the Chinese New Year holidays anyway, so the timing of the epidemic may minimize the need for further shutdowns. Similarly, many government offices and schools had planned holiday closures independently of the virus outbreak. The government has just announced an extension of the holiday period, but many companies will find ways to make up the lost time later in the year. The short-term negative impact is thus likely to be concentrated among restaurants, hotels, and airlines.
Second, all reports indicate that the Wuhan coronavirus is less deadly than SARS (although it may have a faster rate of transmission initially). By implementing aggressive measures to isolate actual and potential patients from the rest of the population, the authorities have also improved their chances in containing the epidemic much sooner. That, in turn, increases the likelihood that the lost economic output this quarter will be offset by increased activity in the remainder of the year.
Third, whether or not China’s trade negotiators realized the severity of the Wuhan virus when they signed the “phase one” trade deal with the United States on January 15, the timing of the agreement has turned out to be fortunate. By greatly increasing its imports of facial masks and medical supplies from the US (and elsewhere), China can simultaneously tackle the health crisis and fulfillits promise under the deal to import more goods.
The virus’s impact on other economies will be even more limited. During the last half-decade, many major central banks have developed models to gauge the economic impact of a slowdown in China on their economies. These models were not built with the current health crisis in mind, but they do take into account trade and financial linkages between China and their respective economies.
As a rule of thumb, the negative impact of a decrease in China’s GDP growth on the US and European economies is about one-fifth as large in percentage terms. For example, if the current coronavirus epidemic lowers China’s growth rate by 0.1 percentage points, then growth in the US and Europe is likely to slow by about 0.02 percentage points. The impact on Australia’s economy may be twice as large, given its stronger commodity-trade and tourism links with China, but a 0.04-percentage-point reduction in growth is still small.
Such calculations assume that the coronavirus does not spread widely to these countries and cause direct havoc. This currently seems unlikely, given the low number of cases outside China.
Of course, the impact on China and other economies could be more severe if the coronavirus crisis were to last much longer than this baseline scenario assumes. In that case, it is important to remember that Chinese policymakers still have room for both monetary and fiscal expansion: the banking-sector reserve ratio is relatively high, and the share of public-sector debt to GDP is still manageable compared to China’s international peers. By using this policy space when necessary, China’s authorities could limit the ultimate impact of the current health crisis.
The coronavirus outbreak is understandably causing alarm in China and elsewhere. From an economic perspective, it is too early to panic.
*本文根據作者發表於《報業辛迪加》上的“Will the Coronavirus Cause a Major Growth Slowdown in China?”（2020年1月27日）一文翻譯，經原作者授權，如需轉載請聯繫授權並註明出處。
*本文作者魏尚進現任復旦大學泛海國際金融學院學術訪問教授、哥倫比亞大學終身講席教授。同時擔任美國國民經濟研究局（NBER）中國經濟研究組創始主任，美國布魯金斯學會（Brookings Institution）高級研究員。曾任亞洲開發銀行（ADB）首位華人首席經濟學家、經濟研究與區域合作局局長，國際貨幣基金組織（IMF）貿易與投資處處長，世界銀行（WB）顧問等職務。
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