Evaluation of immunisation strategies for pertussis vaccines in Jinan, China – an interrupted time-series study

Abstract

Studies in countries with high immunisation coverage suggest that the re-emergence of pertussis may be caused by a decreased duration of protection resulting from the replacement of whole-cell pertussis vaccine (WPV) with the acellular pertussis vaccine (APV). In China, WPV was introduced in 1978. The pertussis vaccination schedule advanced from an all-WPV schedule (1978–2007), to a mixed WPV/APV schedule (2008–2009), then to an all-APV schedule (2010–2016). Increases in the incidence of pertussis have been reported in recent years in Jinan and other cities in China. However, there have been few Chinese-population-based studies focused on the impact of schedule changes. We obtained annual pertussis incidences from 1956 to 2016 from the Jinan Notifiable Conditions Database. We used interrupted time series and segmented regression analyses to assess changes in pertussis incidence at the beginning of each year, and average annual changes during the intervention. Pertussis incidence decreased by 1.11 cases per 100 000 population (P = 0.743) immediately following WPV introduction in 1978 and declined significantly by 1.21 cases per 100 000 population per year (P < 0.0001) between 1978 and 2001. Immediately after APV replaced the fourth dose of WPV in 2008, the second and third doses in 2009, then replaced all four doses in 2010, pertussis incidence declined by 1.98, 1.98 and 1.08 cases per 100 000 population, respectively. However, the results were not statistically significant. There were significant increasing trends in pertussis incidence after APV replacements: 1.63, 1.77 and 1.78 cases/year in 2008–2016, 2009–2016 and 2010–2016, respectively. Our study shows that the impact of an all-WPV schedule may be less than the impacts of the sequential WPV/APV schedules. The short-term impact of APV was better than that of WPV; however, the duration of APV-induced protection was not ideal. The impact and duration of protective immunity resulting from APVs produced in China need further evaluation. Further research on the effectiveness of pertussis vaccination programme in Jinan, China is also necessary.

Impact of Childhood and Maternal Vaccination against Diphtheria, Tetanus, and Pertussis in Colombia

“…In our study, a percentage increase in hospitalization and mortality, higher frequency of cases in the dispersed rural area, and lower laboratory confirmation of cases were observed after the epidemic period compared with the epidemic period. The characteristics of pertussis cases reported during the resurgence in Colombia were similar to those in published works 32 in terms of the higher frequency of cases in children under two months of age and the occurrence of cases in adolescents and adults, whose atypical symptoms make diagnosis difficult.…”

“…6 In China, authors reported a significant reduction in diphtheria, tetanus, and pertussis incidence just after the implementation of the DwPT vaccination program. 32 With respect to diphtheria, a greater reduction in incidence was observed even before the start of vaccination, which could be related to the improvement of socioeconomic conditions of the population. After the start of vaccination, a significant, albeit slow, change in incidence was observed between the pre-and post-vaccination period.…”

“… 6 In China, authors reported a significant reduction in diphtheria, tetanus, and pertussis incidence just after the implementation of the DwPT vaccination program. 32 …”

Impact of the COVID-19 pandemic on neonatal admissions in a tertiary children’s hospital in southwest China: An interrupted time-series study

“…Post-slope is a continuous variable, where pre-COVID period is code 0 and COVID-impacted period takes the same value as the time variable. β1 represents the estimate at the baseline level of the outcome at time zero before the NPIs; β2 estimates the level of change in the rate immediately after the NPIs; β3 represents changes in trends after the NPIs, and εt is the error term of the model [ 13 , 14 ]. The Durbin–Watson (DW) method was used to detect and exclude the time series data stability.…”

Clinical characteristics of 967 children with pertussis: a single-center analysis over an 8-year period in Beijing, China

“…Since the introduction of pertussis vaccine in the 1940s and 1950s, the incidence of pertussis has declined remarkably worldwide, with 266,000 cases per year reported in the USA before the introduction of the vaccine, and only approximately 1000 cases per year reported in the 1980s after the introduction of the vaccine [ 1 ]. The incidence of pertussis in China has also declined significantly since the introduction of universal immunization programs in 1978; consequently, the incidence dropped from 100‒200 per 100,000 in the 1960s and 1970s to less than 1 per 100,000 in the late 1990s and stabilized at less than 0.2 per 100,000 from 2006 to 2010 [ 2 ]. In the past decade, however, epidemiological surveillance in developed countries such as those in Europe and the USA, where vaccine coverage is high, has revealed a gradual increase in the incidence of pertussis, known as the “resurgence of pertussis” [ 3 , 4 ].…”