Hospitalization rates for pneumococcal pneumonia in adults 65 and older in Portugal — which had been increasing on average by 16% per year before pneumococcal conjugate vaccines became available — began to reverse once PCVs became available for infants. The reduction in the elderly, over expected rates, was greatest after the introduction of PCV13.
Health
Malnourishment is one factor contributing to the severity of cholera
The presence of malnourishment correlates with the severity of cholera illness. Additional factors include the number of V. cholerae bacteria ingested, lack of immunity from prior exposure or vaccination, pregnancy, lack of breast-feeding, immunocompromised state, reduced ability to produce gastric acid, and having blood group O.
Immunizing infants against rotavirus in Japan led to fewer hospitalizations due to herd immunity
In Nagoya, Japan, hospitalizations due to rotavirus (RV) decreased sharply in children 2-4 years of age once the percent of infants vaccinated against RV climbed to around 80%. Few of these older children had likely received the vaccine, suggesting that they were protected as a result of herd immunity.
High measles vaccination coverage in Ethiopia linked to lower rates of acute malnutrition in children
An analysis conducted in areas of Ethiopia with high proportions of refugees found that high measles vaccination coverage was linked to lower rates of acute malnutrition (wasting) in children under five. For each percentage point increase in measles vaccination coverage, there was a 0.65% decrease in the rate of acute malnutrition in these areas.
Vaccinating children against pneumonia also reduced ear infections and saved healthcare costs
Over a four-year period following the introduction of PCV-10 in Finland, purchases of antimicrobials that are recommended for the treatment of acute otitis media (middle-ear infection) for children born during these years fell by nearly 18%, compared to pre-vaccine years, and the rate of surgeries to place ear tubes for severe cases fell 15%. Although it is considered a mild disease, acute otitis media caused by pneumococcus is 1,000 times more common in young children than invasive pneumococcal disease, such as pneumonia or meningitis, and thus the public health impact of the vaccine in reducing otitis media cases and in saving health care costs is considerable.
Vaccinating infants significantly reduces hospitalizations from pneumonia
According to a study using local epidemiological data in China, vaccinating infants with pneumococcal conjugate vaccine (PCV-13), using a 3+1 schedule, would prevent more than 10 times as many deaths from invasive pneumococcal disease and pneumonia in unvaccinated individuals (147,500 per year) than it would prevent directly in those vaccinated (12,800 per year). This would be due mainly to a reduction in hospitalizations for pneumonia.
Catch-up vaccination can protect unvaccinated individuals, reducing disease burden across communities
A study in rural Kenya, over a 4-year period following the introduction of the 10-strain pneumococcal conjugate vaccine for infants, that included a catch-up vaccination campaign for children 12-59 months of age, suggests that the catch-up vaccination for older birth cohorts may have been a key factor in protecting unvaccinated individuals and speeding up the reduction of the disease in the community. In contrast, a study in The Gambia, where no catch-up campaign took place, found no herd effects during the first three years following the introduction of PCV-13 for infants.
The Gambia study publication referenced can be found at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4909992/
Immunizing children against pneumonia also provides protection for unvaccinated people through herd immunity
A study of the 10-strain pneumococcal conjugate vaccine in rural Kenya demonstrated herd protection. Over a 4-year period following the introduction of the vaccine for infants, coupled with a “catch-up” campaign for all children 12-59 months of age, the incidence of invasive pneumococcal disease (IPD) caused by the strains in the vaccine fell by 100% in infants less than two months of age who were too young to be vaccinated. In adults (≥ 15 years old) the incidence of IPD fell by 81% and in 5-14 year olds the incidence fell by nearly 75%. The chances of unvaccinated persons becoming ill with any strain of the disease also fell significantly – by 87% in infants under two months old, by nearly half (47%) in 5-14 year olds, and by more than one-third (37%) in adults.
Cholera vaccination programs for children in slums also reduces incidence in adults through herd effects
According to a modeled data study on cholera transmission in Bangladesh, a cholera vaccination program for 1-14 year olds in the slums of Dhaka, Bangladesh involving periodic (every 3 years) campaigns would reduce cholera incidence in adults living in these areas by 40% due to the herd effects of oral cholera vaccines.
Frequent or longer episodes of diarrhea in infancy can lead to chronic health issues in adulthood
Those who experienced more frequent or longer episodes of diarrhea as an infant were more likely to have metabolic syndrome as adults. A longitudinal study in Guatemala found that diarrhea episodes in early infancy are associated with chronic health issues later in life. Each 1% increase in diarrhea burden in children 0-6 months was associated with a 3% increased prevalence in high blood pressure in adulthood. Similarly, a 1% increase in diarrhea burden in older infants 6-12 months was associated with a 4% increased prevalence in elevated waist circumference in adulthood.