[The transformation of the IMSS in the face of the health crisis caused by COVID-19 and the challenges of the 21st century].

The Mexican Social Security Institute, the most prominent social security institution in Mexico, plays a significant role in Mexican health care. Throughout almost eight decades of existence, it has faced significant challenges, whose experiences have contributed to the generation of health policies in the country. Recently, the health emergency caused by COVID-19 evidenced a strong impact of the epidemiological transition associated with the high prevalence of chronic-degenerative diseases, which meant an increased risk of complications and death when facing emerging diseases. The institute is transformed through changes in its policies and forms of health care for the population to provide innovative responses and fulfill the commitment to provide social security to our country.