"The extent to which the coronavirus impacts our operations will depend on future developments, which are highly uncertain and cannot be predicted with confidence," the drugmaker added.
The outbreak that began in Wuhan at the end of last year has killed over 2,700 in China, with over 78,000 confirmed cases of infection, and has now spread to several other countries.
Merck & Co on Wednesday said the outbreak has negatively affected some of its clinical trials and has seen a limited effect on its supply chain of drugs into and raw materials out of China.
Merck, in its regulatory filing, also warned of a negative impact to its first quarter results, which it expects to not be material. The company added it was currently unable to determine whether the outbreak will have a further impact on its results in 2020.