In his message of consolation to Pakistan's leader, Xi said he wished Arif a quick recovery. Xi also said that the two countries remain "all-weather partners in strategic cooperation," Xinhua reported.
"The Chinese government and people will always work steadily with Pakistan to combat the pandemic," Xi said in his letter.
The Chinese president also said he "attaches great significance to the development of China-Pakistan relations," and that Beijing is "ready to cooperate with President Albi to build a closer Chinese-Pakistan community for a shared future between our two countries and our people."
Alvi, 71, said on Monday on Twitter that he "tested positive for COVID-19."
"May Allah have mercy on the people affected by the coronavirus," Alvi said.
Alvi had been administered the first dose of the Sinopharm vaccine March 15, according to Taiwan News. The vaccine is delivered in two shots.
Other top officials in Pakistan have said they tested positive for COVID-19, including Defense Minister Pervez Khattak. Last month, Pakistan's Prime Minister Imran Khan and his wife, Bushra Bibi, also were infected with the novel coronavirus, reports said.
China donated its Sinopharm vaccine to Pakistan in February as part of its vaccine diplomacy campaign with developing countries. The vaccine has an efficacy rate of 72.5%, the Wuhan Institute of Biological Products had said.
Sinopharm and Sinovac have applied to be included on the World Health Organization's emergency use list. Chinese officials are confident the vaccines will be approved by the end of April, according to Chinese state tabloid Global Times on Thursday.