Researchers in Scotland have found that health care planners cannot predict indirect pneumococcal conjugate (PCV) vaccine impacts on hospitalizations rates. According to the study, invasive pneumococcal disease surveillance across all age groups is needed to assess the indirect effects of PCV in the community.
The study titled “Pneumonia hospitalizations in Scotland following the introduction of pneumococcal conjugate vaccination in young children,” was published in the journal BMC Infectious Diseases.
Lower respiratory tract infections, primarily pneumonia, were the second leading cause of morbidity and fourth leading cause of mortality across all age groups globally in 2013.
The burden of pneumonia is disproportionately higher in young children and the elderly (above age 65). Pneumococcal conjugate vaccine (called PCV13) protects against 13 types of pneumococcal bacteria, and is routinely given to children at 2, 4, 6, and 12–15 months of age. It is also recommended for children and adults with certain health conditions. The earlier pneumococcal vaccine is called PCV7.
Prior to the introduction of the pneumococcal conjugate vaccine (PCV) in the U.S., hospitalization rates for pneumonia among the elderly increased by about 20 percent during the 15-years between data collections from 1988–1990 and 2000–2002. The increase has been attributed to an ageing population, increase in the prevalence of coexisting illnesses, and changes in coding and hospital admission practice.
To assess the impact of PCV7 and PCV13 immunization on the rates of hospitalization due to all-cause pneumonia across all age groups in Scotland, Harish Nair, from the University of Edinburgh, and colleagues examined hospital records and linked them with death certification datasets for the entire Scottish population.
The researchers included all cases of pneumonia. They calculated differences in hospital admission rates for pneumonia by age group using the difference in average annual rates for each period of time.
The results revealed that all-cause pneumonia hospitalization rates in children less than 2 years old decreased by about 30 percent in the period after the introduction of the PCV-13. They then compared hospitalization rates with the period before the PCV introduction and found that in adults ages 75–84 years and greater than 85 years, there was an increase in the hospitalization rates due to all-cause pneumonia in the period after the introduction of the PCV 13.
This increase in the hospitalization rates from the post-PCV 13 period compared with the pre-PCV period, resulted in an additional 7,000 hospitalizations across all age groups in Scotland in 2012 — about half of which were in adults older than 75 years.
Also found was a decrease in the average hospital stay length by 33 percent in children less than 2 years old and by about 20 percent in adults over 75 years old in the post-PCV13 period compared to the pre-PCV period.
In addition, the results showed there was an 11% reduction in deaths due to all-cause pneumonia, and 30% reduction in pneumococcal hospitalizations across all age groups in the post-PCV13 period compared with pre-PCV period.
Based on overall study results, the researchers suggest that the decline in hospitalization rates for all-cause pneumonia in children and the decrease in proportion of hospitalizations due to pneumonia in children with pneumococcal disease in the post-PCV period “should alleviate concerns that pneumococcal serotype replacement may have resulted in an increased pneumonia burden in this age group.”
Researchers concluded: “The indirect impact of child PCV immunization in those not vaccinated (in terms of reduction in all-cause pneumonia hospitalizations in the elderly) has not been seen in Scotland. Our results are likely to be confounded by changes in clinical coding and healthcare practices over the same period.”
