Response to “Letter to the Editor: Vaccine Failures in Pediatric Cases Caused by Streptococcus pneumoniae Serotype 19A”

ABSTRACT

We are happy to answer to the Letter from Ozkaya-Parlakay et al. to the Editor commenting on our recent paper, 1  investigated impact of the 13-valent pneumococcal conjugate vaccine (PCV13)  on the incidences of community-acquired pneumonia and pneumonia-related hospitalizations in children ≤5 years after its implementation into the national immunization program (NIP) of Turkey.   Ozkaya-Parlakay et al. draw attention to vaccine failure and importance of continuous  surveillance of relevant disease especially in the perspective of  Streptococcus pneumoniae  serotype 19A. They supported their opinion by their clinical observation of seven children who were vaccinated with PCV13 developed empyema and meningitidis caused by Streptococcus pneumoniae  serotype 19A 
 in Turkey.

KEYWORDS:

• Pediatric
• community-acquired pneumonia
• invasive pneumococcal disease

We are happy to answer to the Letter from Ozkaya-Parlakay et al. to the Editor commenting on our recent paper,¹ investigated impact of the 13-valent pneumococcal conjugate vaccine (PCV13) on the incidences of community-acquired pneumonia and pneumonia-related hospitalizations in children ≤5 years after its implementation into the national immunization program (NIP) of Turkey. Ozkaya-Parlakay et al. draw attention to vaccine failure and importance of continuous surveillance of relevant disease especially in the perspective of Streptococcus pneumoniae serotype 19A. They supported their opinion by their clinical observation of seven children who were vaccinated with PCV13 developed empyema and meningitidis caused by Streptococcus pneumoniae serotype 19 A
in Turkey. First of all, we like to emphasize that in our study we investigated the impact of PCV13 on the incidence of all cause community-acquired pneumonia in children ≤5 years of age without identification of etiological causes of pneumonia. Supporting our findings previously we have shown that the incidence of AOM and tympanic tube insertion incidence in children ≤5 years of age decreased significantly after PCV13 implementation into the Turkish NIP during the same time period and same research hospitals of aforementioned study.² Secondly, despite the recent technological advances, interpretation of diagnostic tests for determining the etiology of pneumonia can still be challenging. Simply detecting a potential pathogen in the upper or lower respiratory tract from a patient with pneumonia does not necessarily mean that it is the cause of pneumonia. Some pneumonia pathogens can also colonize the upper airways of healthy individuals (e.g., S. pneumoniae). Therefore, distinguishing colonization from infection is a major challenge when these organisms are detected in sputum specimens. Also, its well known that especially in children with pneumonia obtaining sputum is very problematic and most of them do not effectively produce sputum. Moreover, all of the major viruses that cause pneumonia are more commonly associated with nonpneumonic upper respiratory tract infection, and virus shedding can occur for a long period of time after symptoms have disappeared. For those reasons, we cannot make any specific conclusion regarding PCV13 vaccine failure in our study population. Thirdly, Oligbu G et al. evaluated pneumococcal conjugate vaccine failure in children by systematic review and found a very low rate of childhood PCV failure in industrialized countries with established national immunization programs, irrespective of the conjugate vaccine or priming or boosting schedule used.³ They showed that children with vaccine failure accounted for around 2% of total invasive pneumococcal disease cases and almost half had significant underlying comorbidities. On the other hand, recent study done by Berman-Rosa M et al. investigated efficacy and effectiveness of the PCV-10 and PCV13 vaccines against invasive pneumococcal disease by systematic review. They reported that in children <12 months of age, PCV13 vaccine effectiveness against serotype 19A post-primary series was significant for the 3 + 1 schedule but not the 2 + 1 schedule.⁴ This study therefore highlights clinical observation of Ozkaya-Parlakay et al. and importance of their perspective especially for our country Turkey where recently PCV13 vaccination schedule shifted from 3 + 1 into 2 + 1 schedule for this reason there after change of PCV13 schedule continuous surveillance of pneumococcal disease is very important.