Impact of immunization programs on 11 childhood vaccine-preventable diseases in China: 1950-2018

Abstract

To evaluate the achievements of China's immunization program between 1950 and 2018, we chose 11 vaccine-preventable diseases (VPDs) as representative notifiable diseases and used annual surveillance data obtained between 1950 and 2018 to derive disease incidence and mortality trends. Quasi-Poisson and polynomial regression models were used to estimate the impacts of specific vaccine programs, and life-table methods were used to calculate the loss of life expectancy, years of life lost, and loss of working years. The total notification number for the 11 VPDs was 211,866,000 from 1950 to 2018. The greatest number occurred in 1959, with a total incidence of 1,723 per million persons. From 1978 to 2018, a substantial decline was observed in the incidence of major infectious diseases. The incidence of pertussis fell 98% from 126.35 to 1.58 per million, and the incidences of measles, meningococcal meningitis, and Japanese encephalitis fell 99%, 99%, and 98%, respectively. The regression models showed that most of the 11 diseases exhibited dramatic declines in morbidity after their integration into the Expanded Program on Immunization (EPI), while varicella and paratyphoid fever, which were not integrated into the EPI, showed increased morbidity. From 1978 to 2018, the total life expectancy for the 11 VPDs increased by 0.79 years, and similar results were obtained for different age groups. China has had great success in controlling VPDs in recent decades, and improving vaccination coverage is a key aspect of controlling VPDs in China.

Keywords: China; immunization; morbidity; mortality; vaccine-preventable diseases.

Graphical abstract

Figure 1

Annual incidence rate of the 11 selected vaccine-preventable diseases and six long-studied diseases in China from 1950 to 2018 The blue line in the large chart shows the incidence rate of the 11 vaccine-preventable diseases (VPDs), and the pink line represents the six diseases that have been continually monitored since 1950 in China (here called long-studied diseases: Japanese encephalitis, diphtheria, meningococcal meningitis, measles, poliomyelitis, pertussis). Since the incidence rates of the remaining five diseases were only available after 1990, the two lines overlap before that year. The small chart shows the incidence of the six long-studied diseases from 1990 to 2015.

Figure 2

Annual mortality rate of 11 selected VPDs and six long-studied diseases in China from 1950 to 2018 The blue line represents the mortality rate of the 11 VPDs, and the pink line represents the six long-studied diseases. Since the mortality rates of the remaining five diseases were only available after 1990, the two lines overlap before that year.

Figure 3

Detailed annual incidence rates of the 11 VPDs in China, 1950–2018

Figure 4

Annual number of cases (top) and deaths (bottom) for the 11 selected VPDs in 1977, 2001, 2008, and 2018

Figure 5

Total incidence of the six long-studied diseases in different provinces in China since 1950 The national distribution of the incidence rates of the six long-studied diseases: the darker the color, the higher the incidence rate. Chongqing became a municipality directly under the central government in 1997; prior to 1997 it belonged to Sichuan Province, so disease epidemic data were not listed separately until 1997. When calculating the incidence before 1997, we used the incidence rate of Sichuan Province. In addition, subregional information for the 11 diseases was only collected in 2016.

Figure 6

Decrease in life expectancy caused by infectious diseases from 1978 to 2018 Impact of the 11 studied VPDs on life expectancy from 1978 to 2018 (the lines were smoothed by using locally estimated scatterplot smoothing regression). The life expectancy from 2004 to 2018 was calculated from the census data of China in 2010. Since we did not have data for the third and fourth censuses, which were conducted in 1982 and 1990, the life expectancy from 1978 to 2003 was calculated according to the census data of China in 2000. We were unable to obtain the incidence data of each age group for measles, meningococcal meningitis, and Japanese encephalitis from 1978 to 2003 and for hepatitis A and hepatitis B from 1990 to 2003. We used the incidence ratios of each age group in 2004 for our calculation. The incidence ratio of each age group in 2017–2018 was calculated according to the incidence ratio in 2016. For better comparison, the age-specific proportion of each disease was calculated as the proportion of the 11 studied diseases.