Missed Opportunities for Measles, Mumps, and Rubella (MMR) Immunization in Mesoamerica: Potential Impact on Coverage and Days at Risk

<div><p>Background</p><p>Recent outbreaks of measles in the Americas have received news and popular attention, noting the importance of vaccination to population health. To estimate the potential increase in immunization coverage and reduction in days at risk if every opportunity to vaccinate a child was used, we analyzed vaccination histories of children 11–59 months of age from large household surveys in Mesoamerica.</p><p>Methods</p><p>Our study included 22,234 children aged less than 59 months in El Salvador, Guatemala, Honduras, Mexico, Nicaragua, and Panama. Child vaccination cards were used to calculate coverage of measles, mumps, and rubella (MMR) and to compute the number of days lived at risk. A child had a missed opportunity for vaccination if their card indicated a visit for vaccinations at which the child was not caught up to schedule for MMR. A Cox proportional hazards model was used to compute the hazard ratio associated with the reduction in days at risk, accounting for missed opportunities.</p><p>Results</p><p>El Salvador had the highest proportion of children with a vaccine card (91.2%) while Nicaragua had the lowest (76.5%). Card MMR coverage ranged from 44.6% in Mexico to 79.6% in Honduras while potential coverage accounting for missed opportunities ranged from 70.8% in Nicaragua to 96.4% in El Salvador. Younger children were less likely to have a missed opportunity. In Panama, children from households with higher expenditure were more likely to have a missed opportunity for MMR vaccination compared to the poorest (OR 1.62, 95% CI: 1.06–2.47). In Nicaragua, compared to children of mothers with no education, children of mothers with primary education and secondary education were less likely to have a missed opportunity (OR 0.46, 95% CI: 0.24–0.88 and OR 0.25, 95% CI: 0.096–0.65, respectively). Mean days at risk for MMR ranged from 158 in Panama to 483 in Mexico while potential days at risk ranged from 92 in Panama to 239 in El Salvador.</p><p>Conclusions</p><p>Our study found high levels of missed opportunities for immunizing children in Mesoamerica. Our findings cause great concern, as they indicate that families are bringing their children to health facilities, but these children are not receiving all appropriate vaccinations during visits. This points to serious problems in current immunization practices and protocols in poor areas in Mesoamerica. Our study calls for programs to ensure that vaccines are available and that health professionals use every opportunity to vaccinate a child.</p></div

Estimates of MMR coverage among children attending health facilities based on MMR stock and ORS stock^*.

<p>MMR: measles, mumps, rubella vaccine. ORS: oral rehydration salts.</p><p>*Excluding children without health cards. If the child has completed the number of required doses for age with proper time interval and not before the eligibility window, they are considered compliant. Children are matched to health facilities based on caregiver-reported usual location for vaccination as matched to the baseline measurement of the SM2015 Health Facility Survey. El Salvador is not included because usual facility for vaccination was not ascertained.</p><p>†Among health facilities that had MMR in stock on the day of the survey.</p><p>Estimates of MMR coverage among children attending health facilities based on MMR stock and ORS stock^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139680#t009fn002" target="_blank">*</a>}.</p

Descriptive characteristics comparing children with and without a vaccine card (% unless otherwise noted).

<p>† N varies by variable due to missing values.</p><p>* p<0.05</p><p>** p<0.01</p><p>*** p<0.001</p><p>Descriptive characteristics comparing children with and without a vaccine card (% unless otherwise noted).</p

Child, maternal, and household characteristics associated with a child having a vaccine card^†.

<p>OR: odds ratio. CI: confidence interval.</p><p>Exponentiated coefficients; 95% confidence intervals in brackets</p><p>* p<0.05</p><p>** p<0.01</p><p>*** p<0.001</p><p>†Models adjusted for all variables in the table</p><p>Child, maternal, and household characteristics associated with a child having a vaccine card<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139680#t002fn006" target="_blank">^†</a>.</p

Coverage cascade of MMR by country.

<p>* Coverage for children 13.5–59 months.</p><p>† Excluding children without vaccination cards. If the child has completed the number of required doses for age, they are considered compliant.</p><p>‡ Excluding children without vaccination cards. If the child has completed the number of required doses for age and not before the eligibility window, they are considered compliant.</p><p>Coverage cascade of MMR by country.</p

Proportions of children with measles immunization information from caregiver recall, health cards, and dried blood spots.

<p>This figure displays the proportion of surveyed children aged 12 to 23 months in Mexico and Nicaragua with measles immunization information from survey and biomarker sources. Many caregivers struggled to recall the type and number of vaccines given, but we were able to collect health card documentation and DBS from a majority of children in both countries. This study focuses primarily on children with both health card and DBS sources, comprising 62.6% of the sample in Mexico and 67.1% of the sample in Nicaragua.</p