South Korea officially declared an end to the country’s first Middle East Respiratory Syndrome, or MERS, outbreak in three years.

The Korea Centers for Disease Control and Prevention(KCDC) made the announcement on Tuesday in line with guidelines set by the World Health Organization(WHO). 

The WHO standards require no new infections for a minimum of 28 days, which is twice the length of the virus’ incubation period.

On September 21st, the KCDC lowered its MERS alert level to the lowest grade after no new cases had been reported in the previous two weeks and 21 people who came into close contact with the first patient all tested negative for the virus. 

South Korea reported its first MERS case in three years on September eighth when a man was diagnosed with the virus after returning home from a three-week business trip to Kuwait via the United Arab Emirates.