The Public Health Legacy of Polio Eradication in Africa.

The legacy of polio in Africa goes far beyond the tragedies of millions of children with permanent paralysis. It has a positive side, which includes the many well-trained polio staff who have vaccinated children, conducted surveillance, tested stool specimens in the laboratories, engaged with communities, and taken care of polio patients. This legacy also includes support for routine immunization services and vaccine introductions and campaigns for other diseases. As polio funding declines, it is time to take stock of the resources made available with polio funding in Africa and begin to find ways to keep some of the talented staff, infrastructure, and systems in place to work on new public health challenges. The partnerships that helped support polio eradication will need to consider funding to maintain and to strengthen routine immunization services and other maternal, neonatal, and child health programs in Africa that have benefitted from the polio eradication infrastructure.

Polio outbreak investigation and response in Somalia, 2013.

BACKGROUND: For >2 decades, conflicts and recurrent natural disasters have maintained Somalia in a chronic humanitarian crisis. For nearly 5 years, 1 million children <10 years have not had access to lifesaving health services, including vaccination, resulting in the accumulation by 2012 of the largest geographically concentrated cohort of unvaccinated children in the world. This article reviews the epidemiology, risk, and program response to what is now known as the 2013 wild poliovirus (WPV) outbreak in Somalia and highlights the challenges that the program will face in making Somalia free of polio once again. METHODS: A case of acute flaccid paralysis (AFP) was defined as a child <15 years of age with sudden onset of fever and paralysis. Polio cases were defined as AFP cases with stool specimens positive for WPV. RESULTS: From 9 May to 31 December 2013, 189 cases of WPV type 1 (WPV1) were reported from 46 districts of Somalia; 42% were from Banadir region (Mogadishu), 60% were males, and 93% were <5 years of age. All Somalian polio cases belonged to cluster N5A, which is known to have been circulating in northern Nigeria since 2011. In response to the outbreak, 8 supplementary immunization activities were conducted with oral polio vaccine (OPV; trivalent OPV was used initially, followed subsequently by bivalent OPV) targeting various age groups, including children aged <5 years, children aged <10 years, and individuals of any age. CONCLUSIONS: The current polio outbreak erupted after a polio-free period of >6 years (the last case was reported in March 2007). Somalia interrupted indigenous WPV transmission in 2002, was removed from the list of polio-endemic countries a year later, and has since demonstrated its ability to control polio outbreaks resulting from importation. This outbreak reiterates that the threat of large polio outbreaks resulting from WPV importation will remain constant unless polio transmission is interrupted in the remaining polio-endemic countries.

Effectiveness of oral polio vaccination against paralytic poliomyelitis: a matched case-control study in Somalia.

BACKGROUND: After the last case of type 1 wild poliovirus (WPV1) was reported in 2007, Somalia experienced another outbreak of WPV1 (189 cases) in 2013. METHODS: We conducted a retrospective, matched case-control study to evaluate the vaccine effectiveness (VE) of oral polio vaccine (OPV). We retrieved information from the Somalia Surveillance Database. A case was defined as any case of acute flaccid paralysis (AFP) with virological confirmation of WPV1. We selected two groups of controls for each case: non-polio AFP cases ("NPAFP controls") matched to WPV1 cases by age, date of onset of paralysis and region; and asymptomatic "neighborhood controls," matched by age. Using conditional logistic regression, we estimated the VE of OPV as (1-odds ratio)×100. RESULT: We matched 99 WPV cases with 99 NPAFP controls and 134 WPV1 cases with 268 neighborhood controls. Using NPAFP controls, the overall VE was 70% (95% confidence interval [CI], 37-86), 59% (2-83) among 1-3 dose recipients, 77% (95% CI, 46-91) among ≥4 dose recipients. In neighborhood controls, the overall VE was 95% (95% CI, 84-98), 92% (72-98) among 1-3 dose recipients, and 97% (89-99) among ≥4 dose recipients. When the analysis was limited to cases and controls ≤24 months old, the overall VE in NPAFP and neighborhood controls was 95% (95% CI, 65-99) and 97% (95% CI, 76-100), respectively. CONCLUSIONS: Among individuals who were fully vaccinated with OPV, vaccination was effective at preventing WPV1 in Somalia.