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Changes in serotype distribution may hamper efficacy of pneumococcal conjugate vaccines in children
B H Normark1, A Ortqvist, M Kalin
1Department of Bacteriology, Swedish Institute for Infectious Disease Control, Solna. Birgitta.Henriques@smi.ki.se
Insights
Pneumococcal bacteremia incidence increased in Sweden. Local pneumococcal conjugate vaccine (PCV) coverage is low, necessitating tailored, adaptable vaccines for effective disease control.
Area of Science:
- Microbiology
- Epidemiology
- Vaccinology
Background:
- An increasing incidence of pneumococcal bacteremia has been observed in Sweden over the past decade.
- Pneumococcal conjugate vaccines (PCVs) are under consideration for introduction into routine childhood vaccination programs globally, including in Sweden.
Purpose of the Study:
- To analyze the temporal distribution of pneumococcal serotypes in invasive isolates in Sweden.
- To evaluate the potential vaccine coverage of new pneumococcal conjugate vaccines using Swedish invasive isolates.
Main Methods:
- Collection of 1136 invasive pneumococcal isolates from Swedish microbiological laboratories across three time points: 1987, 1992, and 1997.
- Analysis of serotype distribution over time.
- Assessment of potential vaccine coverage rates for new conjugate vaccines against the collected isolates.
Main Results:
- The serotype distribution of invasive pneumococcal isolates in Sweden exhibited fluctuations over the study period.
- A notably low potential coverage rate was observed for the 7-valent pneumococcal conjugate vaccine in Sweden, contrasting with findings from other countries.
- Significant temporal variations in serotype prevalence were identified.
Conclusions:
- Pneumococcal conjugate vaccines must be specifically tailored to address current, local serotype patterns in Sweden.
- The effectiveness of pneumococcal conjugate vaccines may require periodic updates to match evolving serotype distributions over time.
- Current vaccine formulations may not provide optimal protection against the predominant pneumococcal serotypes circulating in Sweden.
Abstract:
During the last 10 y we have observed an increased incidence of pneumococcal bacteremia in Sweden. In order to study the serotype distribution over time we collected 1136 invasive pneumococcal isolates from 1987, 1992 and 1997 from Swedish microbiological laboratories. Currently, new pneumococcal conjugate vaccines are being considered for introduction in the general childhood vaccination program in several countries, including Sweden. We studied the potential vaccine coverage rate for the new conjugate vaccines among our Swedish invasive isolates. We found that the serotype distribution fluctuated with time and observed a surprisingly low potential coverage rate for the 7-valent vaccine in Sweden, in contrast to other countries. Therefore we argue that pneumococcal conjugate vaccines have to be tailored to suit current, local serotype patterns and most likely will need to be changed over time.