The Impact of PCV7/PCV13 Implementation on Acute Bacterial Conjunctivitis (ABC) in Children <2 Years in Southern Israel: A Population-Based 11 Years Prospective Study

Background: Marked pneumococcal conjugate vaccine (PCV) impact on respiratory tract infections has been established.  However, no systematic studies of PCV effect on ABC, considered as part of respiratory infections, were conducted.  In otitis media, recent studies demonstrated that reduction of PCV13 pneumococcal serotype diseases was associated with secondary reduction in non-pneumococcal otitis, including cases caused by nontypeable H. influenzae (NTHi) (Ben-Shimol, CID 2016 [in press]).

Methods: We conducted an ongoing, active, prospective, population-based surveillance (Jul-2004 through June-2015) on ABC episodes submitted for culture in  the only laboratory in the region (birth cohort of ~15,000), where >95% of all cultures are submitted, and the population denominators are known, enabling incidence calculation. Bacteriology and pneumococcal serotyping were previously described (PIDJ, 2005;24:823).  Data were compared between the different pathogens: pneumococcus (Pnc), NTHi, M. catarrhalis and S. pyogenes.

Results: A total of 5860 conjunctival cultures from children < 2 years with acute conjunctivitis were obtained, and 2213 (37.8 %) were positive to ≥1 of the 4 studied pathogens. Pneumococcal rates (PCV13, non-PCV13 and overall pneumococcal), in conjunction to implementation of PCVs are shown in Figure 1. The rates by pathogens and overall ABC rates are presented in Figure 2.  The dynamics in rates (expressed by incidence rates ratios [IRRs]) and 95% Confidence Intervals (CIs) are shown in Figure 3.  A significant impact of PCV7/PCV13 implementation on ABC rates (34% reduction) was observed. The highest reduction was with PCV13 serotypes (77%), followed by overall Pnc (48%). Furthermore, a significant reduction in NTHi and mixed NTHi+Pnc rates (23% and 32%, respectively) were also observed.

Conclusion: PCV implementation resulted in reduction of ABC, mainly those caused by PCV13 serotypes, but also of overall single Pnc, Pnc+NTHi and single NTHi, similar to the results observed with OM. It is speculated that by reducing initial damage caused by vaccine-serotype Pnc, further infections by additional pathogens in the respiratory tract, including conjunctivitis, may be reduced.