Abstract
A seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in the Danish childhood immunization program (2+1 schedule) in October 2007, followed by PCV13 starting from April 2010. The nationwide incidence of IPD among children younger than 5 years nearly halved after the introduction of PCV7 in the program, mainly due to a decline in IPD caused by PCV7-serotypes. We report the results from a nationwide population-based cohort study of laboratory confirmed IPD cases in children younger than 5 years during October 1, 2007 to December 31, 2010 and describe the characteristics of children suspected to present with a vaccine failure. The period between April 19 and December 31, 2010 was considered a PCV7/PCV13 transitional period, where both vaccines were offered. We identified 45 episodes of IPD caused by a PCV7 serotype (23% of the total number) and 105 (55%) caused by one of the 6 additional serotypes in PCV13. Ten children had received at least one PCV7 dose before the onset of IPD caused by a PCV7 serotype. Seven children were considered to be incompletely vaccinated before IPD, but only three cases fulfilled the criteria of vaccine failure (caused by serotypes 14, 19F and 23F). One case of vaccine failure was observed in a severely immunosuppressed child following three PCV7 doses, and two cases were observed in immunocompetent children following two infant doses before they were eligible for their booster. None of the IPD cases caused by the additional PCV13 serotypes had been vaccinated by PCV13 and there were therefore no PCV13-vaccine failures in the first 8-months after PCV13 introduction in Denmark.
Highlights
A seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in the Danish childhood immunization program in October 2007
The most frequent situation was a case of invasive pneumococcal disease (IPD) caused by one of the additional serotypes included in PCV13 in a child who had received at least one dose of PCV7 since the beginning of the immunization program
Among cases of non-PCV7/ PCV13 serotypes after PCV13 started to be used, we identified two cases of 12F-IPD, two cases of 24F-IPD and one case caused by 33F serotype, All these patients received at least 2 doses of PCV7 before IPD
Summary
A seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in the Danish childhood immunization program in October 2007. The incidence of invasive pneumococcal disease (IPD) declined markedly, in particular among children younger than 2 years, where the incidence halved compared to the pre-vaccination period [1,2]. The decline was mainly related to a decrease in the incidence of IPD caused by vaccine serotypes (VT-IPD) [2]. These results are consistent with those observed in other industrialized countries and support the high effectiveness of PCV7 against VT-IPD [3–6]. To what has been observed in other countries, cases of VT-IPD are still observed in the population during the post-PCV7 period among children for whom vaccination was offered [8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
