Does MERS Pose a Serious Threat to China?

Last Friday, China confirmed its first case of Middle East Respiratory Syndrome (MERS) in Guangdong province. The now-confirmed South Korean MERS patient, who ignored travel warnings and lied about his conditions when flying to China, had been in close contact with seventy-seven people in the province. As of June 1, sixty-four have been quarantined while the thirteen others remain to be found.

The relatively recent memory of China’s SARS outbreak in addition to the similarities between the diseases has magnified concerns that a similar outbreak could occur with MERS. Also originated in Guangdong, the SARS virus triggered one of the most serious social political crises in China. Like SARS, MERS is caused by a coronavirus (MERS‐CoV) that makes a species jump from animals to humans. Many people with MERS can develop severe complications such as pneumonia. There is currently also no vaccine or drug that works against MERS. Like SARS, a majority of the severe MERS cases are treated with the help of ventilators. But MERS patients generally develop severe acute respiratory illness faster than those with SARS. In critically ill MERS patients, the median time from onset to death is twelve days, compared to twenty-one days for SARS patients. The case fatality rate of MERS is about 40 percent, much higher than H1N1 and SARS. In view of the lethality of the virus, the local hospital that received the first MERS patient purposefully drew mostly from among unmarried medical workers for assignment to the team that would treat potential MERS patients.

But what is the likelihood of the virus evolving into a major outbreak in China? Answer: not very high. First, 90 percent of the MERS cases are concentrated in the Middle East, notably Saudi Arabia. There are indeed cases reported in Europe, Africa, North America, and Asia, but—with Korea an exception—these cases are sporadic and without sustained community transmission.

Second, compared to many infectious diseases, MERS has only limited human to human transmission. The virus is not airborne. Many infections are hospital acquired or caused by unprotected close contact with sick family members. On average, one MERS case will lead to 0.6 to 0.7 secondary cases, which makes the virus transmission rate much lower than SARS (on average two to five secondary cases per patient) or Ebola (on average one to two secondary cases per patient). Also, unlike what was found in the SARS outbreak, true MERS “super-spreaders” (i.e., a person who infects a significantly greater number of other people than the average stricken patient) so far have not been identified. The limited transmission of the virus might explain why none of the sixty-four quarantined people who had close contact with the original Korean patient in Guangdong has shown any abnormality.

Third, China has developed a relatively robust surveillance and response capacity to deal with infectious diseases like MERS. Over the past decade, China has increased its spending on public health and completed a four-level disease prevention and control framework starting from the county level up to the national level. Its Internet-based disease reporting system enables hospitals to directly report suspected disease cases to the China Center for Disease Control (CDC). Since 2012, China has reportedly developed an emergency response plan for diseases like MERS and trained its medical staff in how they should handle suspected or probable MERS cases. Indeed, right after the South Korean Ministry of Health alerted China to the situation, it took only four hours for local health authorities to locate and isolate the first MERS case.

These are of course not reasons for complacence. As the director of Guangdong CDC warned, the possibility of more MERS spreading to Guangdong is very high. The symptoms and signs of the infection are often indistinguishable from other respiratory diseases, making it difficult to diagnose especially in countries outside of the Middle East. As shown in the 2013 H7N9 outbreak, there are also continuing gaps in China’s disease reporting and response systems despite the great strides it has made in improving its ability to handle a public health emergency. Equally important, given the dire consequences of a major acute disease outbreak, it makes little sense for China to simply fixate on the probability of a major outbreak while overlooking its impact in assessing the risk posed by MERS. Hence it is important for China to keep a close eye on the trajectory of the virus while continuing to improve its disease prevention and control system.