The Susceptibility to Rubella Virus Infection among Pregnant Women Attending Antenatal Clinics in Unguja, Zanzibar: The Need to Employ Multiple Strategies to Control Congenital Rubella Syndrome in Tanzania

Aims: This study was conducted to determine the proportion of pregnant women susceptible to Rubella virus infection in Zanzibar, the information that might be useful in future control interventions.

Study Design: A cross-sectional hospital-based study.

Place and Duration of Study: The study was conducted in Unguja Zanzibar between May 2023 and July 2023.

Methodology: Sociodemographic and other relevant information were collected from pregnant women attending antenatal clinics using structured questionnaires. Blood samples were collected from each consented woman. Detection of Rubella IgG antibodies was done by an indirect Enzyme Linked Immunosorbent Assay. Data analysis was done by using STATA version 15.

Results: The median age of enrolled participants was 27[Interquartile range (IQR): 23-31] years while the median gestation age was 28 [IQR: 20-32] weeks. Out of 171 participants, 10/171(5.8%) [95% Cl:2-9.6%] were negative to Rubella virus IgG antibodies indicating susceptibility to active Rubella virus infection that can lead to Congenital Rubella Syndrome. On multivariate analysis, history of congenital malformations (OR: 27.4, 95% CI: 1.29-580.5, p=0.033) was significantly associated with susceptibility to Rubella virus infection.

Conclusion: Despite high level of natural immunity, there is a considerable proportion of pregnant women in Zanzibar susceptible to Rubella virus infection necessitating the need for multiple strategies to reach a goal of Congenital Rubella Syndrome elimination.