Early Evidence of Impact of Monovalent Rotavirus Vaccine in Togo

Clinical Infectious Diseases, Apr 2016

Togo introduced monovalent rotavirus vaccine starting 19 June 2014. We compared all-cause acute gastroenteritis (AGE) hospitalizations and rotavirus-associated hospitalizations during the prevaccine period (July 2008–June 2014) to 1 year after vaccine introduction (July 2014–June 2015). The proportion of children with AGE who tested positive for rotavirus declined from 53% (645/1223) in prevaccine years to 36% (68/187) in the postvaccine year (P < .01). The decline only occurred in children <1 year of age who were eligible for vaccination and was greatest during the rotavirus season months, supporting that it was associated with vaccine implementation.

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Early Evidence of Impact of Monovalent Rotavirus Vaccine in Togo

CID Early Evidence of Impact of Monovalent Rotavirus Vaccine in Togo Correspondence: E. Tsolenyanu 1 4 Department of Pediatrics 1 4 National Coordinator for New Vac- cines Surveillance 1 4 Togo (). Clinical Infectious Diseases® 1 4 0 Laboratory Department, Sylvanus Olympio Teaching Hospital of Lomé , Togo 1 The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions , e-mail 2 World Health Organization , Regional Office for Africa, Brazzaville , Congo 3 Department of Paediatrics, Sylvanus Olympio Teaching Hospital of Lomé , Togo 4 Enyonam Tsolenyanu 5 Immunization Focal Point, World Health Organization Country Office , Lomé , Togo 6 Expanded Programme on Immunization, Ministry of Health 7 National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention , Atlanta , Georgia Togo introduced monovalent rotavirus vaccine starting 19 June 2014. We compared all-cause acute gastroenteritis (AGE) hospitalizations and rotavirus-associated hospitalizations during the prevaccine period (July 2008-June 2014) to 1 year after vaccine introduction (July 2014-June 2015). The proportion of children with AGE who tested positive for rotavirus declined from 53% (645/1223) in prevaccine years to 36% (68/187) in the postvaccine year (P < .01). The decline only occurred in children <1 year of age who were eligible for vaccination and was greatest during the rotavirus season months, supporting that it was associated with vaccine implementation. - METHODS Since 2008, sentinel surveillance for AGE and rotavirusassociated hospitalizations among children <5 years of age was conducted in 2 sentinel sites in Lomé (Sylvanus Olympio Teaching Hospital and Be Hospital) using the World Health Organization’s generic protocol [ 10 ]. Children aged <5 years who were examined at the emergency department due to AGE (defined as ≥3 liquid or semiliquid stools per 24 hours lasting <7 days) were included. After written parental consent was granted, a stool sample was collected. An enzyme-linked immunosorbent assay (IDEIA Rotavirus, Oxoid) was used for diagnosis of rotavirus infection according to the manufacturer’s specifications. Batch testing was conducted monthly at the sentinel laboratory of Sylvanus Olympio Teaching Hospital. RESULTS During the prevaccine period from July 2008 to June 2014, a total of 1223 children <5 years of age with AGE were enrolled, of whom 645 (53%) were positive for rotavirus. The proportion of rotavirus-associated hospitalizations ranged from 41% to 61% in prevaccine years (Figure 1A). For the postvaccine period from July 2014 to June 2015, 187 children <5 years of age with AGE were enrolled and 68 (36%) were positive for rotavirus (mid-P exact <.01). This reflects a reduction of 32% in the proportion of rotavirus-positive cases during the first postvaccine year compared with the average of the prevaccine years. During the prevaccine period, the proportion of rotavirusassociated hospitalizations among children <1 year of age hospitalized with AGE ranged from 48% to 62% (Figure 1B); the mean was 54%. This proportion decreased during the 2014– 2015 period to 31% (mid-P exact <.01), representing a decline of 43% from the mean in prevaccine years. Among children 1–4 years of age, the proportion of rotavirus-associated hospitalizations ranged from 30% to 60% (Figure 1C); the mean was 46%. This proportion was 42% in 2014–2015, and the change during the pre- and postvaccine periods was not statistically significant (mid-P exact = .21). The majority of AGE cases (56%) were observed during the period from December to March. The proportion of rotavirus-associated hospitalizations was also high (69%) during these months (Figure 2A). Again, reductions during these peak rotavirus season months during the first postvaccine season were most marked among infants aged 0–11 months (Figure 2B and 2C), whereas declines were not evident in 1- to 4-year-old children. The first dose of RV1 reported coverage increased from 75% in January 2015 to 100% in June 2015 in vaccine age-eligible children. The second dose coverage also increased from 71% to 85% during this period. RV1 vaccine coverage rates in older children were negligible. DISCUSSION We report early evidence of the impact of RV1 in Togo, with rapid and marked reductions in the proportion of AGE hospitalizations associated with rotavirus in the first year after vaccine implementation. The fact that the decline in the postvaccine period was limited to children <1 year of age—who were age eligible for vaccination—and was not seen in unvaccinated children 1–4 years of age supports that it was associated with vaccine implementation, as does the finding that the decline primarily occurred during the months with peak rotavirus activity (December–March). Despite the short duration of post–vaccine introduction surveillance and the small number of children included, our findings support continued vaccination of Togolese children against rotavirus; as vaccine coverage increases and extends to older children, we anticipate even greater declines that should be monitored through continued surveillance. Notes Acknowledgments. The authors acknowledge the Ministry of Health and national Expanded Programme for Immunization in Togo for the guidance and leadership in implementing the new-vaccines surveillance. Disclaimer. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention (CDC) or the World Health Organization (WHO). The views expressed by the authors do not necessarily reflect the views of PATH, the CDC Foundation, the Bill and Melinda Gates Foundation, or GAVI, the Vaccine Alliance. Financial support. Financial support for this project was provided by Gavi, the Vaccine Alliance, supporting new-vaccines surveillance to WHO Regional Office for Africa. Supplement sponsorship. This article appears as part of the supplement “Health Benefits of Rotavirus Vaccination in Developing Countries,” sponsored by PATH and the CDC Foundation through grants from the Bill and Melinda Gates Foundation and GAVI, the Vaccine Alliance. Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed. 1. Liu L , Johnson H , Cousens S , et al. Global, regional, and national causes of child mortality: an updated systematic analysis for 2010 with time trends since 2000 . Lancet 2012 ; 379 : 2151 - 61 . 2. Tate EJ , Burton HA , Boschi-Pinto C , et al. 2008 estimate of worldwide rotavirusassociated mortality in children younger than 5 years before the introduction of universal rotavirus vaccination programs: a systematic review and meta-analysis . Lancet 2012 ; 12 : 136 - 41 . 3. Parashar UD , Burton A , Lanata C , et al. Global mortality associated with rotavirus disease among children in 2004 . J Infect Dis 2009 ; 200 ( suppl 1 ): S9 - 15 . 4. Curns AT , Steiner CA , Barrett M , et al. Reduction in acute gastroenteritis hospitalizations among US children after introduction of rotavirus vaccine: analysis of hospital discharge data from 18 US states . J Infect Dis 2010 ; 201 : 1617 - 24 . 5. Lanzieri TM , Linhares AC , Costa I , et al. Impact of rotavirus vaccination on childhood deaths from diarrhea in Brazil . J Infect Dis 2011 ; 15 : e206 - 10 . 6. Bayard V , DeAntonio R , Contreras R , et al. Impact of rotavirus vaccination on childhood gastroenteritis-related mortality and hospital discharges in Panama . J Infect Dis 2012 ; 16 : e94 - 8 . 7. David RL , Kirk MD . Rotavirus gastroenteritis hospitalisations following introduction of vaccination, Canberra . Commun Dis Intell Q Rep 2014 ; 38 : E3 - 8 . 8. Armah GE , Sow SO , Breiman RF , et al. Efficacy of pentavalent rotavirus vaccine against severe rotavirus gastroenteritis in infants in developing countries in subSaharan Africa: a randomised, double-blind, placebo-controlled trial . Lancet 2010 ; 376 : 606 - 14 . 9. Tsolenyanu E , Seheri M , Dagnra A , et al. Surveillance for rotavirus gastroenteritis in children less than 5 years of age in Togo . Pediatr Infect Dis J 2014 ; 33 ( suppl 1 ): S14 - 8 . 10. World Health Organization. Generic protocol for (i) hospital-based surveillance to estimate the burden of rotavirus gastroenteritis in children and (ii) a communitybased survey on utilization of health care services for gastroenteritis in children, Field test version . Geneva, Switzerland: WHO, 2002 . Available at: www.who.int/ vaccines-documents/. Accessed 30 November 2015 .


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Enyonam Tsolenyanu, Jason M. Mwenda, Anoumou Dagnra, Eyal Leshem, Mawussi Godonou, Ibrahim Nassoury, Dadja Landoh, Jacqueline E. Tate, Yawo Atakouma, Umesh D. Parashar. Early Evidence of Impact of Monovalent Rotavirus Vaccine in Togo, Clinical Infectious Diseases, 2016, S196-S199, DOI: 10.1093/cid/civ1182