Invasive Pneumococcal Disease in Tuscany Region, Italy, 2016–2017: Integrating Multiple Data Sources to Investigate Underreporting

Abstract

Invasive pneumococcal disease (IPD) is a vaccine-preventable disease characterized by the presence of Streptococcus pneumoniae in normally sterile sites. Since 2007, Italy has implemented an IPD national surveillance system (IPD-NSS). This system suffers from high rates of underreporting. To estimate the level of underreporting of IPD in 2016–2017 in Tuscany (Italy), we integrated data from IPD-NSS and two other regional data sources, i.e., Tuscany regional microbiological surveillance (Microbiological Surveillance and Antibiotic Resistance in Tuscany, SMART) and hospitalization discharge records (HDRs). We collected (1) notifications to IPD-NSS, (2) SMART records positive for S. pneumoniae from normally sterile sites, and (3) hospitalization records with IPD-related International Classification of Diseases, Ninth Revision, Clinical Modification (ICD9) codes in discharge diagnoses. We performed data linkage of the three sources to obtain a combined surveillance system (CSS). Using the CSS, we calculated the completeness of the three sources and performed a three-source log-linear capture–recapture analysis to estimate total IPD underreporting. In total, 127 IPD cases were identified from IPD-NSS, 320 were identified from SMART, and 658 were identified from HDRs. After data linkage, a total of 904 unique cases were detected. The average yearly CSS notification rate was 12.1/100,000 inhabitants. Completeness was 14.0% for IPD-NSS, 35.4% for SMART, and 72.8% for HDRs. The capture–recapture analysis suggested a total estimate of 3419 cases of IPD (95% confidence interval (CI): 1364–5474), corresponding to an underreporting rate of 73.7% (95% CI: 34.0–83.6) for CSS. This study shows substantial underreporting in the Tuscany IPD surveillance system. Integration of available data sources may be a useful approach to complement notification-based surveillance and provide decision-makers with better information to plan effective control strategies against IPD.

Pneumococcal and Influenza Vaccination Rates and Pneumococcal Invasive Disease Rates Set Geographical and Ethnic Population Susceptibility to Serious COVID-19 Cases and Deaths

“…Invasive pneumococcal disease (IPD) data were accumulated from multiple sources (which occasionally also contained pneumococcal vaccination data): Europe [ 82 , 83 , 84 , 85 ]; Eastern Europe [ 86 ]; German [ 87 ]; Italy [ 88 , 89 , 90 ]; Israel [ 91 ]; Egypt [ 92 ]; Turkey [ 93 ]; Korea [ 94 ]; Japan [ 95 ]; Australia [ 96 ]; New Zealand [ 97 ]; U.K. [ 98 ]); U.S. [ 99 , 100 ]); Argentina [ 101 ]; Brazil ([ 102 ]; Canada [ 103 ]; Mexico [ 104 ]; Peru [ 105 ]; Chile [ 106 ]; South Africa [ 107 ].…”

“…A second dataset was accumulated to compare the importance of childhood pneumococcal [88], measles-mumps-rubella [150], and adult influenza [49] vaccination rates on rates of invasive pneumococcal disease [87,88,151] and COVID-19 death rates [152] in the twenty-one regions of Italy. Rates of adult pneumococcal and other vaccinations such as polio, diphtheria, and BCG were not found for more than a handful of regions despite a dedicated search of both PubMed and Google and were insufficient to support statistical analysis.…”

“…The strength of the correlation (R) is Figure 5. Correlation data comparing vaccination rates for measles-mumps-rubella (MMR) among infants and 16-year-olds, influenza (INF) and pneumococcal vaccine (PPV13) among infants with COVID-19 rates of death (per 100,000 population) and the rate of invasive pneumococcal disease (IPD) in regions of Italy (from Table 3) [50,88,89,143,144,149]. With 21 samples and after Bonferroni correction for 25 correlations, R values must be 0.59 or greater to achieve a p-value of less than 0.05.…”

“…MMR (measles-mumps-rubella) vaccination rates do not correlate significantly with any of the other factors (see Figure 5). Images modified and assembled from [50,88,89,[150][151][152]. 3 and analyzed statistically in Figure 5.…”

Impact of vaccination on invasive pneumococcal disease in Italy 2007–2017: surveillance challenges and epidemiological changes

“…Current IPD surveillance system in Italy was rolled out in 2007, yet IPD case notification remains voluntary and surveillance implementation has been progressively improving since then. Limited sensitivity of the current surveillance system has been suggested by a recent Italian study [21] and may be postulated comparing Italian and European data. In 2017, IPD notification rate in Italy was less than half than the EU/EEA average rate (6.23 per 100 000 in 2016, latest data available) [22].…”