Validation of a Novel Forecasting Method for Estimating the Impact of Switching Pneumococcal Conjugate Programs: Evidence from Belgium

Abstract

Introduction: Since 2010, 10-valent (PCV10) and 13-valent pneumococcal conjugate vaccines (PCV13) have been available as part of infant national immunization programs. Belgium is as one of the few countries that implemented PCV13 (2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015), switched to PCV10 (2015)(2016)(2017)(2018) and then switched back to PCV13 (2018-present) after observing increases in disease. We assessed the impacts of both historical and prospective PCV choice in the context of the Belgian health care system and used this experience to validate previously developed economic models. Methods: Using historical incidence (2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) of pneumococcal disease for Belgian children aged \ 16 years, observed invasive pneumococcal disease (IPD) trends from surveillance data were used to estimate future disease in a given PCV13-or PCV10-based program. We compared observed incidence data with two modeled scenarios: (1) the 2015 switch to PCV10 and (2) a hypothetical continuation of PCV13 in 2015. Finally, we explored the potential impact of PCV choice from 2019 to 2023 by comparing three scenarios: (3) continued use of PCV10; (4) a switch back to PCV13;(5) a hypothetical scenario in which Belgium never switched from PCV13. Results: Model predictions underestimated observed data from 2015 to 2018 by 100 IPD cases among ages \ 16 years. Comparing observed data with scenario 2 suggests that PCV13 would have prevented 105 IPD cases from 2015 to 2018 compared with PCV10. Switching to PCV13 in 2019 would avert 625 IPD cases through 2023 compared with continuing PCV10. Scenario never switching from PCV13 would have resulted in a reduction of 204 cases from 2016 to 2023 compared with switching to PCV10 and switching back to PCV13. Conclusion:The findings from this study suggest that previously published modeling results of PCV13 versus PCV10 in other countries may have underestimated the benefit of PCV13. These results highlight the importance of continually protecting against vaccine-preventable pneumococcal serotypes.

Cost-Effectiveness Analysis of the South African Infant National Immunization Program for the Prevention of Pneumococcal Disease

“…Switching from a higher-valent vaccine (PCV13) to a lower-valent vaccine (PCV10-GSK or PCV10-SII) in South Africa could result in a similar phenomenon. Our model may underestimate the true impact of switching from PCV13 to a PCV10 in South Africa, considering that a previous cost-effectiveness study from Belgium using the same model found that switching from PCV13 to PCV10-GSK led to more observed pneumococcal disease cases and deaths than the model estimated [ 15 ]. Therefore, it is important to retain a broad serotype coverage, as this remains relevant to epidemiological considerations.…”

“…Serotype replacement trends were modeled to behave similarly to dynamics observed in Belgium and were set to re-emerge by a factor of 117–166% for serotypes not covered by PCV13. This may be a conservative assumption considering a previous cost-effectiveness study using the same model and assumption actually underestimated the epidemiologic impact of switching to a lower-valent vaccine in Belgium, where PCV13 was switched to PCV10-GSK in 2015 [ 15 ].…”

Clinical and Economic Burden of Pneumococcal Disease Due to Serotypes Contained in Current and Investigational Pneumococcal Conjugate Vaccines in Children Under Five Years of Age

“…However, it remains essential that investigational higher-valent vaccines continue to protect against serotypes contained in currently licensed vaccines and avoid removing vaccine pressure, given that uncovered serotypes can rebound and cause significant disease. Such resurgence was observed in Belgium following the switch from PCV13 to PCV10 in their NIP, which resulted in a significant increase of serotype 19A disease [ 65 – 67 ].…”

Cost-Effectiveness of the 13-Valent Pneumococcal Conjugate Vaccine (PCV13) Versus Lower-Valent Alternatives in Filipino Infants

“…Therefore, the analyses from this study are likely conservative and may underestimate the true impact of switching PCVs in light of serotype re-emergence data observed in Belgium. A Belgium case study that quantifies this underestimation was recently published, demonstrating that vaccine-type disease re-emergence may be more substantial than modeling exercises predict [ 13 ].…”

“…For example, Belgium switched from PCV13-PFE to PCV10-GSK in 2015 because of potential vaccine-related cost-savings and a low perceived risk of disease re-emergence given the local epidemiology (i.e., suppressed vaccine-serotype disease) [ 12 ]. Thereafter, the incidence of IPD due to newly unprotected serotypes, primarily serotype 19A in the case of PCV10-GSK, increased exponentially and the Belgium Superior Health Council made a proactive recommendation to return to PCV13-PFE [ 13 ]. One might need to consider a similar possibility for serotypes 3, 4, and 18C in the case of a switch to PCV10-SII.…”