Low and disparate seroprotection after pentavalent childhood vaccination in the Lao People's Democratic Republic: a cross-sectional study

Evdokimov, Konstantin; Sayasinh, Kong; Nouanthong, Phonethipsavanh; Vilivong, Keooudomphone; Samountry, Bounthome; Phonekeo, Darouny; Strobel, M; Haegeman, F; Heimann, P; Muller, Claude P.; Black, Antony P.

doi:10.1016/j.cmi.2016.10.007

Cited by 21 publications

(39 citation statements)

References 23 publications

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“…Specifically compared with previous studies conducted in Lao PDR, such as Huaphan, a serologic investigation that used non-random sampling of participants with at least 3 documented HBV vaccinations revealed that 17.0% (15/55) were serologically protected (> 10 mIU/mL by serum) at the age of 1–4 years [18]. Another study with 3 documented DTP-Hepatitis B-Hib vaccinations in Vientiane, Khammouane, and Boulhikhamxay provinces in Lao PDR revealed 37.9% (394/1039) of participants were serologically protected (> 10 mIU/mL by serum) at the age of 9–50 months [19]. Thus, unexpectedly low seropositive rates were found among Laotian children with a documented vaccination history in both of these serologic studies [18, 19] nearly as bad as in our study.…”

Section: Discussionmentioning

confidence: 99%

“…Another study with 3 documented DTP-Hepatitis B-Hib vaccinations in Vientiane, Khammouane, and Boulhikhamxay provinces in Lao PDR revealed 37.9% (394/1039) of participants were serologically protected (> 10 mIU/mL by serum) at the age of 9–50 months [19]. Thus, unexpectedly low seropositive rates were found among Laotian children with a documented vaccination history in both of these serologic studies [18, 19] nearly as bad as in our study. Our extremely low rate relative to these two studies may be because we investigated a random sample of children, whereas the two previous serologic investigations investigated non-randomized population samples as well as had differences in study design and methodology, and may also reflect the reality of the situation in hard-to-reach areas where observed cold chain problems can result in inactive vaccine immunization.…”

Section: Discussionmentioning

confidence: 99%

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Serologic testing of randomly selected children after hepatitis B vaccination: a cross-sectional population-based study in Lao People’s Democratic Republic

et al. 2019

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Background Population immunity against hepatitis B virus (HBV) in Lao People’s Demographic Republic (PDR) has not been examined since the national HBV vaccination program was started in 2002. Vaccine has been observed to be frozen at times during cold-chain transport in vaccination programs in Lao PDR and other developing countries, which will inactivate the vaccine. Therefore, this study used post-vaccination serologic testing to evaluate the effects of HBV immunization in Lao PDR. Methods A cross-sectional serologic study was conducted among children (age range, 5–9 years) and mothers (15–45 years) who were randomly selected using probability-proportional-to-size sampling from central Lao PDR. Blood samples were collected as dried blood spots (DBS) and analyzed using chemiluminescent microparticle immunoassay to detect anti-hepatitis B surface (HBs) titers. We also evaluated the correlation between anti-HBs levels measured in DBS and serum among healthy healthcare workers in Vientiane. Results Anti-HBs titers from DBS were strongly correlated with serum levels (correlation coefficient = 0.999) in all 12 healthcare workers evaluated. A linear regression model showed that 10 mIU/mL of serum anti-HBs was equivalent to 3.45 mIU/mL (95% CI: 3.06–3.85) of DBS. Among 911 mother-child pairs tested, 171 children had documentation of vaccination. Of the 147 children who had received ≥3 doses of the hepatitis B vaccine, 1 (0.7%) was positive for anti-HBs. The remaining 24 children received the hepatitis B vaccine only twice, once or no dose. Conclusions The results showed extremely low positivity for anti-HBs among vaccinated children in central Lao PDR. Therefore, post-vaccination serologic testing is important to evaluate population immunity against HBV infection. DBS testing is a potential low-cost tool to evaluating the effectiveness of HBV vaccination programs.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Serologic testing of randomly selected children after hepatitis B vaccination: a cross-sectional population-based study in Lao People’s Democratic Republic

et al. 2019

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“…Despite improvements in healthcare in the Lao People’s Democratic Republic (PDR), the incidence of vaccine-preventable diseases remains high. Vaccination represents one of the most important public health interventions [1–3], but many children fail to respond to the pentavalent diphtheria-tetanus-pertussis (whole cell)–Hepatitis B– Haemophilus influenzae type B vaccine (DTPw-HepB-Hib) vaccine [4], which is scheduled at 6, 10, and 14 weeks after birth. A first dose against hepatitis B is given as a monovalent vaccine within 24 hours after birth (“birth dose”).…”

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confidence: 99%

Seroprotection at Different Levels of the Healthcare System After Routine Vaccination With Diphtheria-Tetanus-Pertussis whole cell–Hepatitis B–Haemophilus influenzae Type B in Lao People’s Democratic Republic

Hefele

Syphan²,

Xayavong³

et al. 2019

Clinical Infectious Diseases

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BackgroundThe Lao People’s Democratic Republic continues to sustain a considerable burden of vaccine-preventable diseases because of incomplete vaccine coverage and weak vaccine responses. We have assessed seroconversion after routine vaccination with the pentavalent vaccine to capture weaknesses of vaccine management at the different levels of the healthcare system.MethodsA total of 1151 children (aged 8–28 months) with 3 documented doses of the pentavalent vaccine delivered at central hospitals in Vientiane and the provincial hospital, 3 district hospitals, and 10 health centers in Bolikhamxay province were enrolled. Sociodemographic information was collected with a standardized questionnaire. Serum samples were analyzed for antibodies against vaccine components, and bivariate and multivariable analyses were performed to identify risk factors for low vaccine responses.ResultsSeroprotection rates at the provincial, district, and health center level were as high as in central hospitals, but seroprotection rates in areas covered by remote health centers were significantly lower. Protective levels also rapidly decreased with age at sampling. Seroprotection rates in Bolikhamxay against the different components reached 70%–77% and were up to 20% higher than in previous studies in the same region; 18.8% more children received the hepatitis B vaccine birth dose and the hepatitis B virus infection rate was 4 times lower.ConclusionsVaccine immunogenicity has dramatically improved in a central province, likely due to training and investment in the cold chain. Nevertheless, there remains a need to focus on the “last mile” in remote areas were most children are vaccinated through outreach activities.

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“…Other reasons, in addition to age at the time of vaccination, whereby children vaccinated at born showed titers between 1 and 9.99 mIU/mL could be an incomplete vaccination schedule or the application of a pentavalent vaccine formulation, which may induce low and uneven aHBs titers [18].…”

Section: Discussionmentioning

confidence: 99%

Hepatitis B surface antibodies seroprevalence among people born before and after implementation of universal HBV vaccination

Lello

Blejer²,

Alter³

et al. 2020

Vaccine

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Universal vaccination is the most effective strategy to control hepatitis B virus (HBV) infection. In Argentina, vaccination against HBV was incorporated in year 2000 for newborns and in 2003 for 11 years old children. However, there is a paucity of data about protection levels against HBV infection. The aim of this work was to determine the prevalence of seroprotective anti-HBs antibodies (aHBs) in Argentina. Serum samples negative for HBsAg and anti-HBc from 132 children born after year 2000 and 762 blood donors, older than 18 years, from five centers across the country, were analyzed for aHBs. Titers !10 mIU/mL were observed in 74/132 children (56.1%) and 336/762 (44.1%) in blood donors. The median age for blood donors was 33.9 (23-43); from them, 210 (27.6%) were born after 1992 and, therefore, were catch-up by vaccine implementation at 11 years old age. Donors born in 1992 or before showed a significantly lower frequency of protection (32.2%) compared to donors born after 1992 (75.2%), p < 0.0001. In addition, significant differences were observed in the status of seroprotection between different participating centers (p = 0.024). Implementation of HBV vaccine in 2000 and 2003 implied an overall increase of the aHBs seroprotective rates, with a particularly adequate response in children vaccinated at 11 years old age. The observed results suggest that population born in 1992 or before is currently the most susceptible. Consequently, it would be advisable to become aware of the risk of transmission in this age group and to stress this population vaccination campaigns.

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Low and disparate seroprotection after pentavalent childhood vaccination in the Lao People's Democratic Republic: a cross-sectional study

Cited by 21 publications

References 23 publications

Serologic testing of randomly selected children after hepatitis B vaccination: a cross-sectional population-based study in Lao People’s Democratic Republic

Serologic testing of randomly selected children after hepatitis B vaccination: a cross-sectional population-based study in Lao People’s Democratic Republic

Seroprotection at Different Levels of the Healthcare System After Routine Vaccination With Diphtheria-Tetanus-Pertussis whole cell–Hepatitis B–Haemophilus influenzae Type B in Lao People’s Democratic Republic

Hepatitis B surface antibodies seroprevalence among people born before and after implementation of universal HBV vaccination

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