Celebrated annually on December 15, World Strengthened Immunity Day aims to raise awareness about the importance of immunization in protecting against vaccine-preventable diseases and to promote the improvement of public health through vaccination.

Established by the World Health Organization (WHO) in 1988, it was a response to the need for a global effort to eliminate polio, a disease that primarily affects children under the age of 5 and can lead to irreversible paralysis. 

The day emphasizes the role of vaccines in preventing the spread of infectious diseases and the collective action needed to maintain high levels of immunity within communities.

Immunity is a physiological function of the human body, primarily carried out by the immune system, which can recognize and eliminate foreign pathogens, as well as identify and deal with damaged cells and tumor cells produced within the body. Vaccines are one of the most cost-effective ways to prevent the spread of infectious diseases.

The 50th anniversary of the Expanded Programme on Immunization (EPI) in 2024 celebrates a WHO-reported saving of more than 154 million lives, with China contributing significantly. 

Since initiating its immunization program in 1978, China has prevented over 300 million cases of diseases like polio, diphtheria and hepatitis B. China has evolved from a vaccine recipient to a donor, protecting its citizens and contributing globally.

Incorporating the hepatitis B vaccine into the national childhood immunization program since 2002, China has achieved over 90 percent coverage in newborns. China is among the earliest countries to launch such immunization initiatives.

"Vaccination rates have led to a continuous decrease in disease incidence, with over 95 percent reduction in many targeted diseases," epidemiologist Feng Zijian told China Media Group in an interview. He added that diphtheria has been virtually eliminated in China for nearly two decades. 

China's immunization program is also supported by its laws and vaccine management system. The 2019 Vaccine Administration Law has provided a legal foundation for industry regulation. After the implementation of the national immunization program, the incidence rate of seven out of 15 targeted diseases in China's expanded immunization program has decreased by more than 99 percent compared to before the use of vaccines.