2018 Assessment of Hepatitis B Surface Antigen Prevalence among Children in the Philippines to Evaluate the Impact of the Hepatitis B Vaccination Program

The Philippines is considered highly endemic for hepatitis B, with an estimated 16.7% of the general population having evidence of chronic hepatitis B virus (HBV) infection. The Philippines introduced the hepatitis B vaccine for infants as part of the National Immunization Program (NIP) in a phased approach in 1991, while the birth dose of the vaccine (HepB-BD) was introduced to cntrol perinatal transmission in 2007. The World Health Organization (WHO) recommends that countries in the Western Pacific Region, including the Philippines, achieve 95% coverage of the HepB-BD and 3-dose infant series.

In May 2018, the Department of Health (DOH), in partnership with WHO, the US Centers for Disease Control and Prevention (CDC) and the Field Epidemiology Training Program Alumni Foundation Inc (FETPAFI), conducted a serosurvey among children aged 5 and 6 years old to estimate the prevalence of the hepatitis B surface antigen (HBsAg) among children born after the nationwide hepatitis B introduction. Questionnaires assessing routine vaccination coverage were administered and blood specimens collected to test for serologic evidence of infection through a rapid, point-of-care HBsAg test.

The survey covered 25 provinces/ cities, with a total of 2,686 child respondents. As of June 26, 2018, approximately 11,874 households have been visited in 244 barangays nationwide. However, out of the 2,059 households with eligible children, only 1,493 have been successfully interviewed and tested after obtaining the consent from parents/ legally-authorized guardians (LAR) (See Annex A). Around 489 parents/ LAR (or 23.7%) refused to participate in the survey, while another 77 households were unable to participate due to the unavailability of either the child or his/her parent/ LAR, or the failure to collect blood samples during the team’s first visit.

Several issues and concerns encountered have significantly hampered the implementation of the survey in the field. These include:

1. Challenges in the coordination and communication of survey information, from the national to the barangay level;
2. Unwillingness of some local government units (LGUs) to participate in a DOH-led activity;
3. Revisions and finalization of the translated informed consent forms (ICFs) to be used in the survey;
4. Start of the academic school year, leading to the unavailability of eligible children during visits;
5. Intermittent rains and inclement weather conditions and terrain in some areas; and
6. Prevailing perceptions caused by the Dengvaxia^TM controversy and circulating social media message regarding ISIS-linked individuals pretending to be DOH personnel and infecting people with AIDS.