An Indicator-based Method To Prioritize Vaccines For Inclusion Into The National Immunization Program Of China

ObjectiveTo develop a method to prioritize exsting,non-program vaccines for inclusion into the National Immunization Program and support evidence-based inclusion of future vaccines into the National Immunization Program.MethodsMethods of research on the construction of indicator system for vaccine inclusion in National Immunization ProgramThrough review of the scientific literature on vaccines and vaccine preventable diseases(VPDs)and World Health Organization(WHO)principles and considerations for adding a vaccine to a national immunization program,a list of 36 factors that are potentially important for decision making about inclusion of a vaccine into China’s National Immunization Program was developed.Using in-depth interviews,immunization program experts organized and refined the factors to develop an indicator-based framework for evaluating vaccines for inclusion into the National Immunization Program.The factors were categorized into three levels,each level a finer-grained refinement of a higher-level factor.The top-level factors concerned the VPD,the vaccine,the ability to ensure program and vaccine production capacity,international experience,and the societal impact of vaccination.National-level senior experts in public health,immunology,epidemiology and health statistics,health economics,clinical medicine,and infectious diseases were conducted two rounds of expert consultation using a questionnaire-based modified Delphi technique.In the first round,39 experts improved the list of factors based on importance and expert familiarity and judgment,and considered alternative factors;results were scored by the boundary value method and experts were used to discuss again to determine the final indicators.In the second modified Delphi technique round,38 experts assigned weightings to the factors and reduced the total number of factors that would be considered and scored in the vaccine round.The experts also assigned numeric scores indicating their familiarity with the prioritization study and their source of knowledge about the factors(theory,direct experience,opinions of others,or their own opinion).Methods of research on priority of the inclusion of five vaccines in National Immunization ProgramThree criteria were used to screen 41 non-program vaccines for consideration in the third(vaccine)modified Delphi technique round:(1)the vaccine is suitable for children,(2)the vaccine is produced by at least three domestic manufacturers,and(3)the vaccine is recommended by WHO for inclusion into national programs fitting China’s epidemiological situation.Five vaccines-varicella vaccine,group A and group C meningococcal polysaccharide conjugate vaccine,Haemophilus influenzae type b conjugate vaccine,inactivated influenza vaccine,and inactivated enterovirus 71 vaccine-met all three criteria.In the third modified Delphi technique round,30 experts assigned numeric scores from zero to 10 to the most detailed of the three-level set of indicators-the 26-factor third level.The numeric scores were multiplied by the weighting factors and the means of the scores were summed to determine a single numeric value for each of the five vaccines.The value represented the priority for inclusion of the vaccine into China’s National Immunization Program.ResultsThirty-nine experts participated in the first round;their concordances on the importance of the three levels of indicators were 0.486,0.356 and 0.275 for levels 1,2,and 3(p<0.05),indicating consistency.Thirty-eight experts participated in the second round;their concordances on the average of indicator importance,necessity,and feasibility of the three levels of indicators were 0.405,0.340,and 0.236,for levels 1,2,and 3(p<0.05),indicating consistency.The experts’ self-evaluation of their knowledge from round 1 was 0.84,and from round 2 was 0.86(values above 0.7 are considered to show good confidence in knowledge and indicate the results will be reliable).After the second round of modified Delphi expert consultation,the set of indicators was reduced from five to three first-level indicators,increased from 11 to 13 second-level indicators,and reduced from 36 to 26 third-level indicators.Weightings of the three top-level indicators(VPDs,vaccines,and capacity of the public health system to deliver the vaccine)were 0.420,0.371 and 0.209,respectively.The weighting coefficients of the second-level indicators(epidemiological characteristics,economic burden,importance of prevention and control,non-vaccine intervention characteristics,vaccine characteristics,cost-effectiveness,vaccine supply,international experience,domestic experience,funding,acceptability,ethics,implementation ability)ranged from 0.038 to 0.126.The weighting coefficients of the third-level indicators ranged from 0.018 to 0.081.Concordance of the experts’weightings were 0.608,0.530,and 0.827 for the three levels,respectively(p<0.05).In round three,30 experts used the weighted factors for each of the five selected vaccines.After weighting the expert’s numeric responses and summing their averages,the sequence and average scores of the five vaccines for consideration to be included in the National Immunization Program were:varicella vaccine(6.91),group A and group C meningococcal polysaccharide conjugate vaccine(6.83),Haemophilus influenzae type b conjugate vaccine(6.74),inactivated influenza vaccine(6.56),and inactivated enterovirus 71 vaccine(6.17).Expert concordance values were 0.301,0.221,0.388,0.303,and 0.253 for the five vaccines,respectively(p<0.05,showing consistency).By vaccine,the sequence of concordance from high concordance to lower concordance was Haemophilus influenzae type b conjugate vaccine,inactivated influenza vaccine,varicella vaccine,inactivated enterovirus 71 vaccine,and group A and group C meningococcal polysaccharide conjugate vaccine.ConclusionsA modified Delphi technique was used to determine the indicator system for the inclusion of vaccines into China’s National Immunization Program.The experts produced concordant weightings and scorings during three rounds of modified Delphi consultation,giving confidence in the credibility of the results.The experts’ recommendations on priority for incorporating five vaccines into the National Immunization Program reflected national needs for disease prevention and control and were in line with both the recommendations of WHO and the actual situation in China.