TY - JOUR
T1 - Evaluation of nationwide supplementary immunization in Lao people’s democratic republic
T2 - Population-based seroprevalence survey of anti-measles and anti-rubella igg in children and adults, mathematical modelling and a stability testing of the vaccine
AU - Hachiya, Masahiko
AU - Miyano, Shinsuke
AU - Mori, Yoshio
AU - Vynnycky, Emilia
AU - Keungsaneth, Phath
AU - Vongphrachanh, Phengta
AU - Xeuatvongsa, Anonh
AU - Sisouk, Thongchanh
AU - Som-Oulay, Vilasak
AU - Khamphaphongphane, Bouaphan
AU - Sengkeopaseuth, Bounthanom
AU - Pathammavong, Chansay
AU - Phounphenghak, Kongxay
AU - Kitamura, Tomomi
AU - Takeda, Makoto
AU - Komase, Katsuhiro
N1 - Publisher Copyright:
© 2018 Hachiya et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2018/3
Y1 - 2018/3
N2 - Background Measles outbreaks have occurred in some countries despite supplementary immunization activities (SIA) using measles-containing vaccine with high vaccination coverage. We conducted a cross-sectional seroprevalence survey to estimate population immunity in Lao People’s Democratic Republic where repeated mass immunization has failed to eliminate measles. Methods and findings In this nationwide multistage cluster sampling survey conducted in 2014 based on probability proportionate to size sampling, blood samples were collected from 2,135 children and adults living in 52 randomly selected villages. Anti-measles and anti-rubella IgG were measured, and IgG prevalence was calculated. We applied mathematical modelling to estimate the number of cases of congenital rubella syndrome (CRS) in 2013 that were averted by the 2011 SIA. A stability testing was applied to the MR vaccine at 4C, 25C, and 35C to examine stability differences between measles and rubella vaccine components. Measles IgG prevalence was significantly lower in the target age groups (5–21 years) of the 2011 SIA using a combination vaccine for measles and rubella vaccine (MR vaccine) than in young adults (22–39 years) (86.8% [95% CI: 83.0–90.6] vs. 99.0% [98.3–99.8]; p<0.001), whereas rubella IgG prevalence was significantly higher (88.2% [84.5–91.8] vs. 74.6% [70.7–78.5]; p<0.001). In the SIA target age groups, prevalence of measles IgG, but not rubella IgG, increased with age. CRS cases prevented in 2013 ranged from 16 [0–50] to 92 [32–180] if the force of infection had remained unchanged or had been reduced by 75%, respectively. In freeze-dried conditions, the measles vaccine component was more heat sensitive than the rubella component. Conclusions Inconsistent IgG prevalence between measles and rubella in Lao PDR can be partly explained by different stability of the measles and rubella vaccine components under heat exposure. Suboptimal vaccine handling may cause insufficient immunogenicity for measles, which subsequently leads to an outbreak despite high SIA coverage, while direct evidence is lacking. Temperature monitoring of the vaccine should be conducted.
AB - Background Measles outbreaks have occurred in some countries despite supplementary immunization activities (SIA) using measles-containing vaccine with high vaccination coverage. We conducted a cross-sectional seroprevalence survey to estimate population immunity in Lao People’s Democratic Republic where repeated mass immunization has failed to eliminate measles. Methods and findings In this nationwide multistage cluster sampling survey conducted in 2014 based on probability proportionate to size sampling, blood samples were collected from 2,135 children and adults living in 52 randomly selected villages. Anti-measles and anti-rubella IgG were measured, and IgG prevalence was calculated. We applied mathematical modelling to estimate the number of cases of congenital rubella syndrome (CRS) in 2013 that were averted by the 2011 SIA. A stability testing was applied to the MR vaccine at 4C, 25C, and 35C to examine stability differences between measles and rubella vaccine components. Measles IgG prevalence was significantly lower in the target age groups (5–21 years) of the 2011 SIA using a combination vaccine for measles and rubella vaccine (MR vaccine) than in young adults (22–39 years) (86.8% [95% CI: 83.0–90.6] vs. 99.0% [98.3–99.8]; p<0.001), whereas rubella IgG prevalence was significantly higher (88.2% [84.5–91.8] vs. 74.6% [70.7–78.5]; p<0.001). In the SIA target age groups, prevalence of measles IgG, but not rubella IgG, increased with age. CRS cases prevented in 2013 ranged from 16 [0–50] to 92 [32–180] if the force of infection had remained unchanged or had been reduced by 75%, respectively. In freeze-dried conditions, the measles vaccine component was more heat sensitive than the rubella component. Conclusions Inconsistent IgG prevalence between measles and rubella in Lao PDR can be partly explained by different stability of the measles and rubella vaccine components under heat exposure. Suboptimal vaccine handling may cause insufficient immunogenicity for measles, which subsequently leads to an outbreak despite high SIA coverage, while direct evidence is lacking. Temperature monitoring of the vaccine should be conducted.
UR - https://www.scopus.com/pages/publications/85044997105
U2 - 10.1371/journal.pone.0194931
DO - 10.1371/journal.pone.0194931
M3 - Article
C2 - 29596472
AN - SCOPUS:85044997105
SN - 1932-6203
VL - 13
JO - PLoS ONE
JF - PLoS ONE
IS - 3
M1 - e0194931
ER -
