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Reductions in Childhood Pneumonia Mortality After Vaccination in the United States

BACKGROUND

We aim to estimate the magnitude of the reduction in pneumococcal pneumonia and meningitis mortality after the mass introduction of pneumococcal conjugate vaccine (PCV)7 and PCV13 in children in the United States.

METHODS

We assessed the trends in mortality rates from pneumococcal pneumonia and meningitis, in the United States between 1994 and 2017. We fitted an interrupted time-series negative binomial regression model (adjusted by trend, seasonality, PCV7/PCV13 coverage, and H. influenzae type b vaccine coverage) to estimate the counterfactual rates without vaccination. We reported a percent reduction in mortality estimates relative to the projected no-vaccination scenario, using the formula 1 minus the incidence risk ratio, with 95% confidence intervals (CIs).

RESULTS

Between 1994 and 1999 (the prevaccination period), the all-cause pneumonia mortality rate for 0-1-month-old children was 2.55 per 100,00 pop., whereas for 2-11 months-old children, this rate was 0.82 deaths per 100,000 pop. During the PCV7-period in 0-59-month-old children in the United States, the adjusted reduction of all-cause pneumonia was 13% (95% CI: 4-21) and 19% (95% CI: 0-33) of all-cause meningitis For PCV13, the reductions in this age group were 21% (95% CI: 4-35) for all-cause pneumonia mortality and 22% (95% CI: -19 to 48) for all-cause meningitis mortality. PCV13 had greater reductions of all-cause pneumonia than PCV13 in 6-11-month-old infants.

CONCLUSIONS

The universal introduction of PCV7, and later PCV13, for children 0-59 months old in the United States was associated with decreases in mortality due to all-cause pneumonia.

Effect of pneumococcal conjugate vaccine introduction on childhood pneumonia mortality in Brazil: a retrospective observational study

Background

Understanding the real-world effect of pneumococcal conjugate vaccines (PCVs) on pneumonia mortality is crucial because of the expectation that increased PCV use will substantially reduce the burden of pneumonia deaths in children younger than 5 years. However, few post-vaccine introduction studies have estimated the benefits of PCV use on childhood mortality and results have been inconsistent. Therefore, we set out to assess the effect of introduction of ten-valent pneumococcal conjugate vaccine (PCV10) on pneumonia mortality in children in Brazil.

Methods

In this retrospective observational study, we used publicly available mortality data of children aged 3–59 months in Brazil. We separated data by age group (3–11 months, 3–23 months, and 3–59 months) and stratified data by three different socioeconomic factors of Brazilian municipalities (in 2010): Human Development Index, proportion of children living in extreme poverty, and proportion of mothers with no primary education. We first examined long-term trends in childhood pneumonia mortality in Brazil (from 1980 to 2014). We then assessed the effect of PCV10—introduced in Brazil in 2010—both nationally and in municipalities stratified by socioeconomic status, with a synthetic control approach as our primary analytical method.

Findings

Between 1980 and 2010, a period during which Brazil's Human Development Index rose substantially, national pneumonia mortality in children younger than 5 years decreased from about 150 to 15 deaths per 100 000 children younger than 5 years. Despite rapid uptake of PCV10 after its introduction in 2010, we observed a further vaccine-associated decline of about 10% in national childhood pneumonia mortality with our primary analytical method, with a high degree of uncertainty in the estimates. We observed larger reductions in municipal childhood pneumonia mortality in all three age groups (3–11 months, 3–23 months, and 3–59 months) in municipalities with a high percentage of extreme childhood poverty and mothers with no primary education, with the largest decrease observed in children aged 3–23 months in municipalities with low maternal education (24%, 95% credible interval 7–35).

Interpretation

The large reduction observed from 1980 to 2010 in national pneumonia mortality in children younger than 5 years underscores that improvements in nutrition, hygiene, education, and health care have an important role in reducing pneumonia mortality. Although the PCV-associated reduction in childhood pneumonia mortality at the national level was modest, we found that PCV led to larger reductions in low-income municipalities. Similarly, large benefits might occur when PCVs are introduced in other low-income settings.

Funding

Bill & Melinda Gates Foundation and National Institute of Allergy and Infectious Diseases.

Dengue hospitalisations in Brazil: annual wave from West to East and recent increase among children

The number of dengue epidemics in Brazil has increased dramatically in the last 15 years. In this study, we analysed the seasonal patterns in the incidence of hospitalisations due to dengue across the different states of Brazil and compared these with the corresponding climatic patterns. We discovered that the seasonality of dengue hospitalisations in Brazil has a clear zonal gradient, characterised by the progression of primary peaks from West to East during the first half of the year, which may be associated with the increased vapour pressure and rainfall during this period, leading to increased mosquito abundance and activity. We also found that the proportion of children among hospitalised individuals was especially high during the peak outbreaks in 2007/2008 and 2010. This may be due to the emergence and spread of the new DENV-2 Southeast Asian genotype lineage II from 2007, which has probably arrived from the Caribbean and may have caused an increase in incidence and severity of the disease, particularly among children. Our findings may allow health systems to improve control interventions and contribute to reducing dengue morbidity and mortality by using integrated vector control in conjunction with early diagnosis and prompt supportive care.

Rotavirus vaccination takes seasonal signature of childhood diarrhea back to pre-sanitation era in Brazil

OBJECTIVES

This study aimed to examine the previously unknown long-term spatio-temporal patterns in diarrheal morbidity and mortality across age groups and geography in Brazil under the light of evolving socioeconomic factors and interventions.

METHODS

Nationwide mortality (1979-2014) and hospitalization (1998-2014) data were obtained from the Brazilian Ministry of Health. Analyses of long-term secular trends and seasonality of diarrheal morbidity and mortality were performed in EPIPOI (www.epipoi.info).

RESULTS

For most states, the primary peak in mortality risk among children under 5 years occurred from December-April (summer/early autumn) from 1979-1988. From 2000-2005 (before the 2006 implementation of rotavirus vaccination), the pattern switched to June-October (winter/early spring). By 2007-2014, the peak in mortality shifted back towards summer/early autumn. A similar pattern was observed for hospitalizations. These patterns were particularly apparent in non-equatorial regions of the country. In contrast, the risk of diarrhea-related death among older children (5-19 years) did not demonstrate well-defined seasonality or spatial patterns.

CONCLUSIONS

Rotavirus vaccination policies were associated with a shift in the timing of seasonal peaks in children under 5, reminiscent of the summer diarrhea period common decades prior. Additionally, young children were shown to have distinct disease patterns compared to other age groups, suggesting different etiologies.