Zika Virus May Affect the Universal Two-Child Policy: A New Challenge for China

Toward the end of 2015, China relaxed its more than three-decade-old one-child policy to address the problems of a rapidly aging population, now allowing all couples to have two children (the universal two-child policy) [1]. It is expected that China will witness a huge baby boom in the next few years [2]. However, the potential threat of Zika virusmay affect the anticipated baby boom. As of August 3, 2016, more than 1.5 million people in 68 countries and territories have been affected by Zika virus, including 51 countries and territories with a first reported outbreak since2015 [3]. Among them, the United States reportedmosquito-borne Zika virus transmission for the first time on July 29, 2016. Fourteen countries or territories have reportedmicrocephaly and other central nervous system (CNS) malformations to be potentially associated with Zika virus infection or suggestive of congenital infection [3,4]. The primary transmission vectors of Zika virus are Aedes aegypti and A. albopictus; however, mounting evidence shows that the virus may be transmitted through Culexpipiens and A. triseriatus, sexual intercourse, blood transfusion, laboratory exposure, and frommother to child [3,5,6]. On February 1, 2016, the World Health Organization declared Zika virus to be a Public Health Emergency of International Concern [4], and many technical guidances, including case definition for Zika virus, information for travelers visiting Zika-affectedcountries, pregnancymanagement in the context of Zika virus, and prevention of sexual transmission of Zika virus have been released [7]. Both Zika and dengue viruses are primarily transmitted by the Aedes mosquitoes; therefore, Zika virusmay attain the same geographical spread as dengue virus [8]. Considering the fact that cases of dengue have been reported in China during each of the past 25 years and have reached a historical high in 2014 (47,056 cases) [9], it is possible for a Zika virus epidemic to occur in China. In particular, the following contributing factors are worth noting. First, China has the primary transmission vectors (A. aegypti and A. albopictus) (Fig 1) and a suitable climate for the prevalence of Zika virus. Besides,most of the Chinese people have not acquired immunity against the virus. Second,mosquitoes or larvae infected with Zika virus may be introduced to China with commodities [10].China is the largest trading nation in the world. It has been reported that some of its major trading partners have cases of Zika virus infection, including Brazil (the most affected country). Third, Zika virus can also spread to China through asymptomatic cases because it is impossible to check all inbound travelers. In fact, 22 imported cases were reported in mainland China between February 9, 2016, and July 12, 2016 [11,12]. The rapid development of business and tourism led to an increase in travel, with 523 million people exiting and entering mainland China in 2015, including 51.92 million foreigners [13]. In addition, many Chinese people will travel to Brazil for the 2016 Summer Olympics in Rio de Janeiro [14].Fourth, adult mosquitoes carryingZika virusmay enter China from the