South Korea has almost conquered the explosive Middle East respiratory syndrome (MERS) epidemic that began in May—but not quite. On Tuesday, Korean Prime Minister Hwang Kyo-ahn declared a "de facto end" to the outbreak, but to officially call the country MERS-free, South Korea has to wait 28 days—twice the virus' incubation period—after the last patient has died or cleared the virus, says a spokesperson for the Korea Centers for Disease Control and Prevention (KCDC).
That period hasn't even begun, because one patient, lingering in hospital isolation, continues to test positive for the virus.
A single Korean traveler to the Middle East sparked what became the largest MERS outbreak outside that region when he sought treatment after returning home. Unrecognized until his diagnosis on 20 May, the virus spread among health care workers and patients in several hospitals, resulting in 186 laboratory-confirmed infections. Of those, 36 patients have died, 138 have recovered and been discharged, and 11 remain hospitalized but have cleared the virus from their systems and are recuperating in general wards.
On 27 July, the health ministry announced that all 16,693 of the MERS contacts traced to the May index patient had been released from quarantine. Only the patient who continues to test positive remains in isolation; the 28-day countdown begins when that patient either dies or tests negative. KCDC hopes to get those negative results “soon” the KCDC spokesperson says, in which case the outbreak could be formally declared over by early to mid-September.
But there is a new wrinkle in the saga. Also on 27 July, the health ministry announced that it had placed under quarantine a patient who returned from the Middle East with possible MERS symptoms as well as a number of that traveler's contacts. Another feverish traveler and additional contacts were put under quarantine on 29 July. If all test negative, "they will be released from quarantine as of 12 a.m. on August 1," says a statement on the health ministry's website.
Prime Minister Hwang carefully avoided formally declaring victory against MERS when he spoke earlier this week, but he was keen to send a reassuring message. The South Korean government is trying to get the economy, tourism, and daily life back to normal. Although the chance is very small, "in theory a new outbreak could erupt from this one case," says World Health Organization (WHO) spokesman Christian Lindmeier. But he adds that WHO agrees with the Korean government's message that "citizens can go ahead with their normal lives without being afraid of this virus."