A health worker receives a vaccine against the novel coronavirus (COVID-19), in Leon, Guanajuato state, Mexico, on January 13, 2021. (Xinhua/Mario Armas)

 Some 879 hospitals in Mexico on Wednesday simultaneously began vaccination against the novel coronavirus disease (COVID-19), giving priority to healthcare workers.

The immunization campaign follows the delivery on Tuesday of 439,725 doses of the vaccine developed by US pharmaceutical firm Pfizer and its German partner BioNTech.

Local media reported healthcare workers lined up in an orderly manner to receive the first of the two doses required, at hospitals designated for the treatment of COVID-19 cases.

"We are very happy that vaccination has already begun," the president of Mexico, Andres Manuel Lopez Obrador, said during his usual morning press conference, as images of the campaign were broadcast live.

Applying this first round of vaccines was expected to be completed in three days, said Lopez Obrador.

The next priority group will be the country's 15 million older adults, with vaccination to begin "at the end of January, the beginning of February," he added.

Mexico has registered 1,556,028 cases of COVID-19 infection and 135,682 deaths from the disease since February 2020.