Disparities in Effectiveness of Pneumococcal Vaccine in Industrialized and Developing Countries: Is Vaccination Closing the Gap?.

Background Streptococcus pneumoniae cause serious disease including pneumonia, meningitis and bacteremia and mortality.is seen most in developing countries. The aim of the study was to determine if the reduction in IPD aid pneumonia rates were similar in developed and developing countries after the introduction of the pneumococcal conjugated vaccine and to determine changes in the disparities of these diseases rates in these countries.

Methods: Literature searches were conducted by using the PubMed database and Google scholar. The main criterion for selection was,that the studies compare incidence of IPD or pneumonia in children pre and post PCV7, PCV10, or PCV13 vaccine introduction. Only published articles that described the incidence rate of IPD or pneumonia with quantitative data were fully reviewed in detail.

Results: A total of 22 articles were full-text original publications and one was a review article. Within 3 years of PCV introduction in the United States, all-cause IPD dropped from 98.7/100,000 to 20/100,000 children <5 years of age and similar such reductions were also documented in Europe, Canada, Australia and Israel. In South Africa, rate of IPD incidence among children younger than 2 years of age declined from 54.8 to 21.7 cases per 100,000 from the baseline to 2011 and the further decreased to 17.0 cases per 100,000 person in 2012 (total reduction of 69%. The incidence rates of pneumonia in chil- dren <5 years were estimated to be 0.29,episodes per child-year in developing-and 0.05 episodes per child-year in developed countries. After PCV7 introduction the rates of pneumonia hospitalizations in <5 years old decreased in the US from 1,274/100,000 to 723/100,000 in UK, from 1,340/100,000 children to 1,079/per 100,000 children. In Nicaragua reduction of rate ration of 0.67 (95% CI: 0.59-0.75) among infants and 0.74 (95% CI: 0.67-0.81) among 1 year olds and Uruguay from 1,542/100,000 to 1,227/100,000 -and in South Africa, from -96/1,000 in 2008-2009 to 69.3/1,000 (27.8%).

Conclusions: PCVs are effective in both industrialized and developing countries in reducing IPD and pneumonia. Although developing countries are behind in PCV introduction, there is hope that if PCV is introduced in national immunization programs, IPD can perhaps be reduced to that of levels in industrialized countries, also resulting in reduced levels of pneumonia incidences. More surveillance studies are needed in all countries, but especially in developing countries that have introduced PCV to more accurately determine IPD and pneumonia reduction as a result of vaccination.