 -- The World Health Organization (WHO) has declared the Republic of Guinea Ebola-free.

It has been 42 days "since the last person confirmed to have Ebola virus disease tested negative for the second time," according to a news release from WHO.

The West African country will now undergo a roughly three-month period "of heightened surveillance to ensure that any new cases are identified quickly before they can spread to other people," the United Nations’ agency said.

The original chain of transmission of the virus began in December 2013. The virus then spread to the neighboring countries of Sierra Leone and Liberia, as well as "by land and air travel to seven other countries," including the United States.

Dr. Bruce Aylward, the special representative of the Director-General for the Ebola Response, WHO, said "the coming months will be absolutely critical. This is the period when countries need to be sure that they are fully prepared to prevent, detect and respond to any news cases."

With the New Year approaching, the World Health Organization says "2016 will see the three most-affected countries implementing a full health sector recovery agenda to restart and strengthen key public health programs, especially maternal and child health, while continuing to maintain the capacity to detect, prevent and respond to any flare-up of Ebola."