The U.S. Embassy in Beijing also issued an statement saying the employee recently reported "subtle and vague, but abnormal, sensations of sound and pressure".
The Post reports that Chinese and USA officials are looking into the matter.
The American Foreign Service Association said then that government employees had been diagnosed with "mild traumatic brain injury and permanent hearing loss, with such additional symptoms as loss of balance, severe headaches, cognitive disruption, and brain swelling".
"The (State) Department is taking this incident very seriously and is working to determine the cause and impact of the incident", US Embassy spokeswoman Jinnie Lee told Agence France-Presse. "Instead, move to a location where the sounds are not present".
The embassy spokesperson told CBS News that the Chinese government had "assured us they are also investigating and taking appropriate measures".More news: Iran Threatens to Punch Mike Pompeo in the Mouth
Past year in Cuba, the United States reported that some of its personnel and family members experienced a range of ailments, some after hearing an unusual sound.
"We do not now know what caused the reported symptoms and we are not aware of any similar situations in China, either inside or outside of the diplomatic community", the United States diplomatic statement said.
Charles Rosenfarb, a doctor and director of the State Department bureau of medical services, said the symptoms were mixed but consistent with brain trauma.
The U.S. past year made a decision to withdraw a large number of embassy staff from the country after diplomats stationed there complained of symptoms like hearing loss, dizziness, tinnitus, visual difficulties, headaches, fatigue and other symptoms.
Officials initially suspected the Americans had been targeted by an acoustic weapon, but media reports have suggested that the Federal Bureau of Investigation has been unable to verify any evidence to support that theory. -Cuban relations, while investigators have chased theories including a sonic attack, electromagnetic weapon or a flawed spying device.More news: Nurse dead in Congo as Ebola vaccination campaign starts
The US has held Cuba responsible, either for allowing the suspected attacks to happen or for carrying them out itself.
Last October, the State Department ordered non-essential embassy personnel and the families of all staff to leave Havana, arguing the USA could not protect them from unexplained illnesses that have harmed at least 24 Americans.
The cause of those incidents remains unresolved.
Canadian and U.S. authorities had initially suspected a "sonic attack" or a "mass psychosomatic incident", but those are "now considered unlikely", a senior Canadian official said.More news: Venezuela foreign minister says new U.S. sanctions are…