Rotavirus genotype diversity in Tanzania during Rotavirus vaccine implementation between 2013 and 2018.

The study aims to determine Rotavirus genotypes between 2013 and 2018 during implementation of ROTARIX vaccine in Tanzania. The analysis of surveillance data obtained between 2013 and 2018 was done to determine circulating genotypes after introduction of Rotarix vaccine. From 2013 to 2018, a total of 10,557 samples were collected and screened for Rotavirus using an enzyme immunoassay. A significant decrease in Rotavirus positivity (29.3% to 17.8%) from 2013 to 2018 (OR 0.830, 95% CI 0.803-0.857, P < 0.001) was observed. A total of 766 randomly selected Rotavirus positive samples were genotyped. Between 2013 and 2018, a total of 18 Rotavirus genotypes were detected with G1P [8] being the most prevalent. The G1P [8] strain was found to decrease from 72.3% in 2015 to 13.5% in 2018 while the G9P [4] strain increased from 1 to 67.7% in the same years. G2P [4] was found to decrease from 59.7% in 2013 to 6.8% in 2018 while G3P [6] decreased from 11.2% in 2014 to 4.1% in 2018. The data has clearly demonstrated that ROTARIX vaccine has provided protection to varieties of the wild-type Rotavirus strains. Continuous surveillance is needed to monitor the circulation of Rotavirus strains during this era of vaccine implementation.

Seroprevalence of IgG Rubella among Infants with Features Suggestive of Congenital Rubella Syndrome at a Tertiary Hospital in North Western Tanzania.

Background: Congenital Rubella Syndrome (CRS) is among the causes of infant mortality and lifelong disability due to severe birth defects. There has been an increasing number of neonates born with congenital abnormalities suggesting CRS, at the same time the rubella seroprevalence among pregnant mothers and healthy school children in the northwestern Tanzania has been noted to be alarmingly high. This study aimed to determine prevalence of rubella antibodies and associated factors among infants suspected to have CRS. Methods: This cross-sectional study included 174 infants aged ≤ 12 months with at least one clinical features of CRS. The study was conducted between Septembers 2017 and March 2018 at Bugando Medical Centre, a consultant teaching hospital in North Western Tanzania. Collection of Social demographic and other relevant information was done hand in hand with screening for clinical symptoms suggestive of CRS and Blood samples were collected. Indirect enzyme-linked immunosorbent assay (ELISA) Test were conducted on collected sera to test for specific Rubella IgM and IgG antibodies. Results: The majority of enrolled infants were below 1 year of age; of these 83 (47.7%) were neonates and only 13.2% had received MR vaccine. Out of these, 111 (63.8%, 95%CI: 56.6-70.9) were IgG Rubella seropositive whereas none was IgM Rubella seropositive. In multivariate logistic regression analysis being neonate was the only factor that independently predicted rubella IgG seropositivity (OR 2.3; 95% CI 1.2 - 4.4; p=0.012). Conclusion: A significant proportion children (<12 months) with suspected CRS are IgG seropositive which is predicted by being a neonate (0-4weeks); this indicates high maternal seroprevalence and hence extended surveillance and measures to target women of child bearing age are recommended.

Detection of rotavirus before and after monovalent rotavirus vaccine introduction and vaccine effectiveness among children in mainland Tanzania.

BACKGROUND: Monovalent rotavirus vaccine (RV1) was introduced in Tanzania in January 2013 under the Reach Every Child initiative, to be given at ages 6 and 10 weeks. We used the sentinel hospital rotavirus surveillance system to examine the rotavirus detection rate before and after vaccine introduction and estimate vaccine effectiveness. METHODS: Before vaccine introduction, rotavirus surveillance was established at two mainland hospitals; children admitted for acute diarrhea were eligible for enrollment and stools were tested for rotavirus antigen. We compared the rotavirus positivity rate in the pre-vaccine period (Tanga Hospital, 2009 and 2011; Bugando Medical Centre, 2012) to that from post-introduction years, 2014-2015. In 2013, surveillance was established at 9 additional hospitals. We examined rotavirus positivity among infants at these sites for 2014-2015. We obtained vaccine records and calculated vaccine effectiveness at 3 sites using case-test-negative control design. RESULTS: At Tanga Hospital, the rotavirus positivity rate among infants was 41% (102/251) pre-vaccine and 14% (28/197) in post-vaccine years (rate ratio: 0.35 [95% CI 0.22-0.54]). At Bugando, the positivity rate was 58% (83/143) pre-vaccine, and 18% (49/277) post-introduction (rate ratio 0.30 [95% CI 0.210.44]). Results were similar among children <5 years. At the new sites, the median site rotavirus positivity rate among infants was 26% in 2014 (range 19-44%) and 18% in 2015 (range 16-33%). The effectiveness of ≥1 RV1 dose against rotavirus hospitalization among children 5-23 months was 53% (95% CI: -14, 81), and 66% (95% CI: 9-87) against hospitalization with intravenous rehydration. Following introduction, peak rotavirus activity occurred later in the year and appeared more concentrated in time. CONCLUSION: Rotavirus surveillance data from Tanzania indicate that the rotavirus positivity rate among children hospitalized with diarrhea that were enrolled was substantially reduced after vaccine introduction. Low positivity rates among infants were detected at hospitals across the country. Overall, the data support that rotavirus vaccine has been successfully introduced and is effective in Tanzanian children.