Hepatitis B virus infection on Kwajalein Atoll, Marshall Islands: a seroprevalence, knowledge and attitudes study.

Objective: A study was conducted to determine the seroprevalence of chronic hepatitis B virus (HBV) infection among children and their mothers on Kwajalein Atoll in the Marshall Islands two decades after routine vaccination was introduced in the 1990s. Mothers' knowledge and attitudes towards HBV disease and vaccination were also assessed.

Methods: Results of a national seroprevalence survey conducted in 2016-2017 and antenatal records were used to determine the prevalence of HBV seropositivity in children aged 6-8 years and their biological mothers. The associations between demographic, social and vaccination-related factors and seropositivity were explored using Fisher's exact tests.

Results: HBV seroprevalence was 0.3% in children and 6.8% in their mothers (during pregnancy). Coverage of timely HBV vaccination was 90.3% for the birth dose and was significantly associated with factors related to place of residence (P < 0.001), place of birth (P < 0.001) and number of antenatal visits (P < 0.001). Maternal attitudes towards infant vaccination and antenatal screening were largely positive (95.8% and 96.7%, respectively) despite low vaccination rates (20.9%) among mothers. Knowledge levels were low for disease complications, treatment and transmission.

Discussion: Prevalence of HBV in children and mothers residing on Kwajalein Atoll in 2016-2017 was lower than the national average for the Marshall Islands. Timely birth dose administration appears to have been effective in preventing mother-to-child transmission of HBV in this setting and should be promoted in remote settings where antiviral therapy is not available. Provision of out-of-cold-chain HBV vaccines should be considered to improve access in remote settings.