Pneumococcal Conjugate Vaccine Breakthrough Infections: 2001-2016

Area of Science:

• Pediatric Infectious Diseases
• Vaccinology
• Epidemiology

Background:

• Most countries utilize a 3-dose pneumococcal conjugate vaccine (PCV) schedule for infants.
• The United States has a licensed 4-dose schedule (3 primary doses + 1 booster) for infants.
• Evaluating PCV schedules is crucial for optimizing protection against invasive pneumococcal disease (IPD).

Purpose of the Study:

• To compare the incidence of invasive pneumococcal disease (IPD) breakthrough infections in children who received 2 vs. 3 primary doses of PCV.
• To assess the impact of booster doses on IPD incidence across different primary dose schedules (2+1 vs. 3+1 and 2+0 vs. 3+0).

Main Methods:

• Utilized 2001-2016 Active Bacterial Core surveillance data.
• Identified vaccine-type IPD breakthrough infections in children younger than 5 years who received at least one dose of PCV7 or PCV13.
• Calculated schedule-specific IPD incidence rates (IRs) and compared them using rate differences (RDs) and incidence rate ratios.

Main Results:

• Higher PCV13 IPD breakthrough infection rates were observed in infants under 1 year receiving a 2+0 schedule compared to a 3+0 schedule (IR: 7.8 vs. 0.6).
• PCV7 results showed similar trends.
• The disparity in breakthrough infections between the 2+0 and 3+0 schedules was larger in 2010-2011 than in 2012-2016, correlating with decreased serotype circulation.

Conclusions:

• A 3-primary-dose PCV schedule resulted in fewer breakthrough IPD infections in the first year of life compared to a 2-primary-dose schedule.
• The difference in breakthrough infection rates between schedules diminished as vaccine serotypes became less prevalent in circulation.