Cost-effectiveness of seasonal influenza vaccination in pregnant women, healthcare workers and adults >= 60 years of age in Lao People's Democratic Republic

BACKGROUND

Pregnant women, healthcare workers (HW), and adults >= 60 years have shown an increased vulnerability to seasonal influenza virus infections and/or complications. In 2012, the Lao People's Democratic Republic (Lao PDR) initiated a national influenza vaccination program for these target groups. A cost-effectiveness evaluation of this program was undertaken to inform program sustainability.

METHODS

We designed a decision-analytical model and collected influenza-related medical resource utilization and cost data, including indirect costs. Model inputs were obtained from medical record abstraction, interviews of patients and staff at hospitals in the national influenza sentinel surveillance system and/or from literature reviews. We compared the annual disease and economic impact of influenza illnesses in each of the target groups in Lao PDR under scenarios of no vaccination and vaccination, and then estimated the cost-effectiveness of the vaccination program. We performed sensitivity analyses to identify influential variables.

RESULTS

Overall, the vaccination of pregnant women, HWs, and adults >= 60 years could annually save 11,474 doctor visits, 1,961 days of hospitalizations, 43,027 days of work, and 1,416 life-years due to laboratory-confirmed influenza illness. After comparing the total vaccination program costs of 23.4 billion Kip, to the 18.4 billion Kip saved through vaccination, we estimated the vaccination program to incur a net cost of five billion Kip (599,391 USD) annually. The incremental cost per life-year saved (ICER) was 44 million Kip (5,295 USD) and 6.9 million Kip (825 USD) for pregnant women and adults >= 60 years, respectively. However, vaccinating HWs provided societal cost-savings, returning 2.88 Kip for every single Kip invested. Influenza vaccine effectiveness, attack rate and illness duration were the most influential variables to the model.

CONCLUSION

Providing influenza vaccination to HWs in Lao PDR is cost-saving while vaccinating pregnant women and adults >= 60 is cost-effective and highly cost-effective, respectively, per WHO standards.

Spatial distribution and risk factors of dengue and Japanese encephalitis virus infection in urban settings: the case of Vientiane, Lao PDR

OBJECTIVES

To evaluate the prevalence of flavivirus infection in Vientiane city (Lao PDR), to describe the spatial distribution of infection within this city, and to explore the link between flavivirus seroprevalence and urbanization levels of residential neighbourhoods.

METHODS

A seroprevalence survey was carried out in 2006 including 1990 adults (>or=35 years) and 1568 children (>or=6 months and <6 years) randomly selected.

RESULTS

The prevalence of individuals with previous flavivirus infection (i.e. negative for both DEN and JE IgM but positive for DEN IgG) was 57.7%, with a significantly (P < 0.001) higher prevalence among adults (84.6%; 95% confidence interval (CI) = 82.4-86.8) than children (9.4%; 95% CI = 7.2-11.6). The prevalence of individuals with recent flavivirus infection (i.e. positive for DEN and/or JE IgM) was 6.5% and also significantly (P < 0.001) higher among adults (10.0%; 95% CI = 8.3-11.7) than children (2.5%; 95% CI = 1.5-3.5). In terms of spatial distribution, IgG prevalence was significantly (P < 0.001) higher among individuals living in the central city (60.1%; 95% CI = 56.2-64.1) than among those living in the periphery (44.3%; 95% CI = 41.5-47.2). In contrast, seroprevalence of recent flavivirus infections was significantly (P < 0.001) higher among individuals living in the periphery (8.8%; 95% CI = 6.9-10.7) than in the central city (4.0%; 95% CI = 2.9-5.2). This association was also statistically consistent (P < 0.01) in multivariate logistic regression after controlling for individual risk factors.

CONCLUSIONS

Our findings indicate that the level of urbanization of residential neighbourhoods influences the risk of flavivirus infection. The spatial distribution of flavivirus infection varies, even within a small city of less than 300,000 habitants such as Vientiane.