Increase in invasive pneumococcal disease in children associated with shortage of heptavalent pneumococcal conjugate vaccine.

The authors investigated the impact of heptavalent pneumococcal conjugate vaccine (PCV7) shortage on the rate of invasive pneumococcal disease (IPD). Vaccination status and number of doses delivered was determined. Regression analysis using an exponential decay model was used to predict the expected rate of IPD in the shortage period if IPD continued to decline at the same rate as in the availability period. The rate of IPD decreased from 15.5 to 6.5 with vaccine availability (P < .00001) and increased to 7.2 with shortage (P = .69). Based on the model, IPD rate would have been 3.6 if the decrease continued at the same rate when there was no shortage; this was statistically significant (95% prediction interval, 2.7-4.1). The rate of IPD correlated directly with the number of PCV7 doses delivered, r = -.98. Continuous availability of the PCV7 would have resulted in a statistically significant lower IPD rate compared to the measured IPD rate in the vaccine shortage period.