Resurgence of Pertussis -- The Resurgence of a Vaccine-Preventable Disease in China

Abstract

Abstract Background In 2017, pertussis made a comeback in China. Altogether, 10 390 cases were reported, with an average annual incidence rate of 0.7530 cases per 100 000 people, the most in 24 years. Methods Using epidemiological data of pertussis cases in China from 1950 to 2021 extracted from the National Notifiable Infectious Diseases Surveillance System and the official website of the National Health Commission, we investigated the epidemic of pertussis in China in 2017. The data came from 31 provinces and regions in mainland China, including geographic, seasonality and patient demographic information. Results From 1950 to 2021, there was a cumulative total of 34703090 cases of pertussis. In 2017, 10390 cases were diagnosed, with the annual incidence of pertussis during the 2017–2021 surge is almost 2.5 times higher than the 1991–2016 period (1.1048 vs 0.4279 per 100 000; IRR 2.582, 95% CI 2.503 ~ 2.663; p < 0·0001) and peaked in 2019 (2·1947 per 100 000). In the past 71 years, the hardest hit regions the epidemic has increase from southern China towards northern China and spread to all provinces. The peak incidence is from July to August each year; most cases are children, with the highest annual incidence in 0-year-old children (16.983 per 100,000). In 2017, as compared with 2004 through 2016, incidence increased in younger infants and older children; the percentages of cases according to age group were as follows: 0 to 12 months, 10.23 percent from 2004 through 2016 and 60.86 percent from 2017 through 2018 (P < 0.05); 1 years to 2 years, 2.77 percent and 14.40 percent (P < 0.05); 2 to 6 years, 1.14 percent and 4.17 percent (P = 0.037). Conclusions Since the introduction of universal immunization in 1978, it took only 27 years from the control of the epidemic in 1990 to the recovery. Since the 2017 pertussis resurge in China occurred mainly in children who had been appropriately immunized, it is clear that the diphtheria-pertussis-tetanus vaccine failed to give full protection against the disease.