BackgroundJapanese encephalitis virus (JEV) is an important cause of encephalitis in most of Asia, with high case fatality rates and often significant neurologic sequelae among survivors. The epidemiology of JE in the Philippines is not well defined. To support consideration of JE vaccine for introduction into the national schedule in the Philippines, we conducted a systematic literature review and summarized JE surveillance data from 2011 to 2014.MethodsWe conducted searches on Japanese encephalitis and the Philippines in four databases and one library. Data from acute encephalitis syndrome (AES) and JE surveillance and from the national reference laboratory from January 2011 to March 2014 were tabulated and mapped.ResultsWe identified 29 published reports and presentations on JE in the Philippines, including 5 serologic surveys, 18 reports of clinical cases, and 8 animal studies (including two with both clinical cases and animal data). The 18 clinical studies reported 257 cases of laboratory-confirmed JE from 1972 to 2013. JE virus (JEV) was the causative agent in 7% to 18% of cases of clinical meningitis and encephalitis combined, and 16% to 40% of clinical encephalitis cases. JE predominantly affected children under 15 years of age and 6% to 7% of cases resulted in death. Surveillance data from January 2011 to March 2014 identified 73 (15%) laboratory-confirmed JE cases out of 497 cases tested.SummaryThis comprehensive review demonstrates the endemicity and extensive geographic range of JE in the Philippines, and supports the use of JE vaccine in the country. Continued and improved surveillance with laboratory confirmation is needed to systematically quantify the burden of JE, to provide information that can guide prioritization of high risk areas in the country and determination of appropriate age and schedule of vaccine introduction, and to measure the impact of preventive measures including immunization against this important public health threat.

IntroductionIn line with the regional aim of eliminating rubella and congenital rubella syndrome (CRS), phased introduction of rubella-containing vaccines (RCV) in the Philippines’ routine immunization programme began in 2010. We estimated the burden of CRS in the country before widespread nationwide programmatic RCV use.MethodsWe performed a retrospective chart review in four tertiary hospitals. Children born between 1 January 2009 and 31 December 2014 and identified as possible CRS cases based on the presence of one or more potential manifestations of CRS documented in hospital or clinic charts were reviewed. Cases that met the clinical case definition of CRS were classified as either confirmed (with laboratory confirmation) or probable (without laboratory confirmation). Cases that did not fulfil the criteria for either confirmed or probable CRS were excluded from the analysis.ResultsWe identified 18 confirmed and 201 probable cases in this review. Depending on the hospital, the estimated incidence of CRS ranged from 30 to 233 cases per 100 000 live births. The estimated national burden of CRS was 20 to 31 cases per 100 000 annually.DiscussionThis is the first attempt to assess the national CRS burden using in-country hospital data in the Philippines. Prospective surveillance for CRS and further strengthening of the ongoing measles-rubella surveillance are necessary to establish accurate estimates of the burden of CRS and the impact of programmatic RCV use in the future.

In 2012, the World Health Organization Regional Committee for the Western Pacific Region (WPR) reaffirmed its commitment to eliminate measles and urged WPR member states to interrupt endemic measles virus transmission as rapidly as possible. In 2013, a large measles outbreak occurred in the Philippines despite implementation of measles elimination strategies including a nationwide supplemental immunization activity (SIA) in 2011 using measles- and rubella-containing vaccine and targeting children aged nine months to seven years. To prevent future measles outbreaks a new tool was developed to assess district-level risk for measles outbreaks, based on the WPR polio risk assessment tool previously applied in the Philippines. Risk was assessed as a function of combined indicator scores from four data input categories: population immunity, surveillance quality, program performance, and threat assessment. On the basis of the overall score, the tool assigned each district a risk category of low, medium, high, or very high. Of the 122 districts and highly urbanized cities in the Philippines, 58 (48%) were classified as high risk or very high risk, including the district of the Metro Manila area and Region 4A where the outbreak began in 2013. Risk assessment results were used to guide the monitoring and supervision during the nationwide SIA conducted in 2014. The initial tool drafted in the Philippines served as a template for development of the global risk assessment tool. Regular annual measles programmatic risk assessments can be used to help plan risk mitigation activities and measure progress toward measles elimination.

Rotavirus (RV) is an important cause of diarrheal disease particularly in children aged under 5 years. Monovalent RV vaccine (RVV) was selectively introduced in 2012 in the Philippines and in July 2014 was introduced in the public health program of a province. Two RVV doses are recommended at 6 and 10 weeks of age. We conducted a test negative case-control evaluation to assess the effectiveness of RVV when given in a routine public health program in the Philippines. From September 2014 to August 2017, 967 children aged <5 years were hospitalized with diarrhea and of these, we enrolled 600 who were eligible to have received RVV and provided stool specimens for testing. Among children ≥8 months of age who were age-eligible to have received RVV, at least one dose of RVV had an adjusted vaccine effectiveness (VE) against RV hospitalization of 60% (95% confidence interval, CI: 24%, 79%), and against severe rotavirus diarrhea, VE was 64% (95% CI: 11%, 85%). These findings support the introduction of RVV into routine public health use in the Philippines. However, other factors such as costs, cost-effectiveness and operational issues must be considered prior to adoption of the vaccine into the countries’ public immunization program.

HighlightsStarting in 2012, RVV was introduced in public health clinics of Agusan del Sur province.Declines in diarrheal hospitalizations and consults were seen following RVV introduction.No declines in diarrheal admissions were observed in a province where RVV was not introduced.This is the first evidence of the public health impact of RVV in a middle income country Asia.