Control of vaccine preventable infectious disease in China

Abstract

Abstract of thesis entitled

Control of Vaccine Preventable Infectious Disease in China

Submitted by

Xiang REN

for the degree of Doctor of Philosophy at The University of Hong Kong in February 2020

Control of vaccine preventable diseases (VPD) is a national priority in order to reduce the burden and spread of infectious diseases in China. I analysed national surveillance data on notifiable diseases to determine disease epidemiology and evaluate the effectiveness of disease control and prevention measures, especially the assessment of the Expanded Program on Immunization (EPI) against VPD.

I aimed to inspect historical trends of notifiable diseases and particularly VPD in China and their epidemiological patterns, to determine associated factors for declines in incidence of selected VPD, to estimate the impact of various vaccine strategies on VPD, and to evaluate knowledge, attitudes and behavior (KAB) towards a non-EPI vaccine among the general population and healthcare professionals.

I summarized the development of diagnosis standards and reporting methods of national notifiable diseases reporting system (NNDRS) and described the landscape of the burden of notifiable diseases and VPD in China. Specifically, I then focused on the epidemiology of measles, hepatitis A and hepatitis E in China, assessing various aspects of disease epidemiology, including geographic distribution, seasonality, age distribution and impact of vaccination programmes.

The burden of VPD in China decreased significantly and led to a major decline in notifiable infectious diseases as a whole. In the decades since mass vaccination programmes against hepatitis A and measles via EPI were implemented, notifiable cases of hepatitis A and measles experienced an exponential decrease in contrast with the steadily increasing incidence of hepatitis E cases in China. While the hepatitis E vaccine is not included into EPI yet, both the morbidity and mortality of hepatitis E has now surpassed that of hepatitis A. In addition, to reveal dynamical course of measles historical transmission patterns and to optimize measles vaccination strategy, I conducted SIR modeling on its epidemiological changes and tested the potential impact of different vaccination strategies, finding that independent administration of second dose of measles-containing vaccine (MCV2) targeting on general susceptible population is more effective than administration of MCV2 only targeting on first dose of measles-containing vaccine (MCV1) recipients.

I conducted a random-digit-dialing telephone survey among general population and an internet survey among nurses, finding that influenza-like illness (ILI) rate of children under age 5, adolescents age 5-14 and healthcare professionals were significantly higher than general population, but only young nurses with working experience (0 to 2 years) and nurses working in primary care settings had high influenza vaccine coverage. Vaccination willingness was positively associated with higher education level, recommendation from doctors, cost-free vaccine and vaccination campaign in working community. While the main barriers for nurses to be vaccinated are lack of time, ignorance of time and place for influenza vaccination and lack of confidence in vaccine effectiveness.

In conclusion, vaccination is an essential way to reduce burden of infectious diseases in China, future improvement of vaccination strategy should focus on encouraging key populations at highest risk to vaccinate and should be accompanied by awareness and willingness raising campaigns that promote the benefits of vaccination via healthcare professionals, and reduce obstacles to vaccination like out-of-pocket cost. Word count: 500