Effectiveness of Maternal Influenza Immunization in Mothers and Infants

AimThe evidence needed for tropical countries to take informed decisions on influenza vaccination is scarce. This article reviews policy, availability, use and effectiveness of seasonal influenza vaccine in tropical and subtropical countries.MethodGlobal health databases were searched in three thematic areas – policy, availability and protective benefits in the context of human seasonal influenza vaccine in the tropics and subtropics. We excluded studies on monovalent pandemic influenza vaccine, vaccine safety, immunogenicity and uptake, and disease burden.ResultsSeventy‐four countries in the tropics and subtropics representing 60% of the world's population did not have a national vaccination policy against seasonal influenza. Thirty‐eight countries used the Northern Hemisphere and 21 countries the Southern Hemisphere formulation. Forty‐six countries targeted children and 57 targeted the elderly; though, the age cut‐offs varied. Influenza vaccine supply increased twofold in recent years. However, coverage remained lower than five per 1000 population. Vaccine protection against laboratory‐confirmed influenza in the tropics ranged from 0% to 42% in the elderly, 20–77% in children and 50–59% in healthy adults. Vaccinating pregnant women against seasonal influenza prevented laboratory‐confirmed influenza in both mothers (50%) and their infants <6 months (49–63%).ConclusionGuidelines on vaccine composition, priority risk groups and vaccine availability varied widely. The evidence on vaccine protection was scarce. Countries in the tropics and subtropics need to strengthen and expand their evidence‐base required for making informed decisions on influenza vaccine introduction and expansion, and how much benefit to expect.

Section: Resultsmentioning

confidence: 99%

Seasonal influenza vaccine policy, use and effectiveness in the tropics and subtropics – a systematic literature review

Hirve

Lambach

Paget

et al. 2016

“…Should an influenza vaccination program be introduced in Zambia, young children and the elderly may benefit most from annual influenza immunization. No influenza vaccine is licensed for children aged <6 months, but this group may be protected through the vaccination of their mothers during pregnancy 27, 28. However, given the limited financial resources in our setting, estimation of the disease burden associated with other pathogens should also be considered to inform prioritization of interventions.…”

Section: Discussionmentioning

confidence: 99%

The national burden of influenza‐associated severe acute respiratory illness hospitalization in Zambia, 2011‐2014

Theo

Tempia

Cohen

et al. 2017

BackgroundEstimates of influenza‐associated hospitalization are limited in low‐ and middle‐income countries, especially in Africa.ObjectiveTo estimate the national number of influenza‐associated severe acute respiratory illness (SARI) hospitalization in Zambia.MethodsWe conducted active prospective hospital‐based surveillance for SARI at the University Teaching Hospital (UTH) situated in Lusaka Province during 2011‐2014. Upper respiratory tract samples were tested for influenza virus using a reverse transcriptase polymerase chain reaction assay. We estimated age‐specific rates of influenza‐associated SARI hospitalizations for the UTH using census and secondary data on respiratory hospitalizations following estimation approaches recommended by the World Health Organization. We used the UTH hospitalization rates as a proxy for Lusaka Province. These rates were adjusted for each of the remaining 9 provinces based on their prevalence of risk factors for pneumonia and healthcare‐seeking behavior. Rates were expressed per 100,000 population.Results SARI cases accounted for 77.1% (13 389/17 354) of respiratory admissions at the UTH; 82.7% (11 859/14 344) and 50.8% (1530/3010) among individuals aged <5 and ≥5 years, respectively. Among SARI cases tested, the influenza virus detection rate was 5.5% (152/2734), 4.8% (48/998), and 6.0% (104/1736) among individuals aged <5 and ≥5 years, respectively. The mean annual national number of influenza‐associated SARI hospitalizations was 6181 (95% CI: 4321‐8041—rate: 43.9; 95% CI: 30.7‐57.1); 4669 (95% CI: 3287‐6051—rate: 187.7; 95% CI: 132.1‐243.3) among children aged <5 years; and 1512 (95% CI: 1037‐1987—rate: 13.1; 95% CI: 9.0‐17.2) among individuals aged ≥5 years.ConclusionsThe burden of influenza‐associated SARI hospitalizations was substantial and was highest among children aged <5 years.

“…Should an influenza vaccination program be introduced in Rwanda, young children and the elderly may benefit most from annual influenza immunization. No influenza vaccine is licensed for children aged <6 months, but this group may be protected through the vaccination of their mothers during pregnancy 25, 26…”

Section: Discussionmentioning

confidence: 99%

The national burden of influenza‐associated severe acute respiratory illness hospitalization in Rwanda, 2012‐2014

Nyamusore

Rukelibuga

Mutagoma

et al. 2017

BackgroundEstimates of influenza‐associated hospitalization are severely limited in low‐ and middle‐income countries, especially in Africa.ObjectivesTo estimate the national number of influenza‐associated severe acute respiratory illness (SARI) hospitalization in Rwanda.MethodsWe multiplied the influenza virus detection rate from influenza surveillance conducted at 6 sentinel hospitals by the national number of respiratory hospitalization obtained from passive surveillance after adjusting for underreporting and reclassification of any respiratory hospitalizations as SARI during 2012‐2014. The population at risk was obtained from projections of the 2012 census. Bootstrapping was used for the calculation of confidence intervals (CI) to account for the uncertainty associated with all levels of adjustment. Rates were expressed per 100 000 population. A sensitivity analysis using a different estimation approach was also conducted.Results SARI cases accounted for 70.6% (9759/13 813) of respiratory admissions at selected hospitals: 77.2% (6783/8786) and 59.2% (2976/5028) among individuals aged <5 and ≥5 years, respectively. Overall, among SARI cases tested, the influenza virus detection rate was 6.3% (190/3022): 5.7% (127/2220) and 7.8% (63/802) among individuals aged <5 and ≥5 years, respectively. The estimated mean annual national number of influenza‐associated SARI hospitalizations was 3663 (95% CI: 2930‐4395—rate: 34.7; 95% CI: 25.4‐47.7): 2637 (95% CI: 2110‐3164—rate: 168.7; 95% CI: 135.0‐202.4) among children aged <5 years and 1026 (95% CI: 821‐1231—rate: 11.3; 95% CI: 9.0‐13.6) among individuals aged ≥5 years. The estimates obtained from both approaches were not statistically different (overlapping CIs).ConclusionsThe burden of influenza‐associated SARI hospitalizations was substantial and was highest among children aged <5 years.