Invasive Pneumococcal Disease Risk Higher in Premature Infants

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The invasive pneumococcal disease incidence in premature infants remained nearly twice as high as children who had been born at term.
The invasive pneumococcal disease incidence in premature infants remained nearly twice as high as children who had been born at term.

According to study results published in Clinical Infectious Diseases, invasive pneumococcal disease was significantly higher in premature infants than in infants born at term. Researchers suggested that primary vaccination schedules should consider the risk associated with preterm infant response.

The investigators of this study sought to characterize the epidemiology, clinical features, serotype distribution, and outcomes of invasive pneumococcal disease in infants. They further sought to compare the relative risk of different pneumococcal conjugate vaccines (PCVs), specifically PCV13 and non-PCV13 serotypes, and the overall risk of invasive pneumococcal disease in premature infants and infants born at term.

The study included 517 cases of laboratory-confirmed invasive pneumococcal disease reported to Public Health England between 2013 and 2016. All cases involved infants in their first year of life; vaccination history, comorbidities, symptoms, and outcomes were reported using standard surveillance questionnaires. Prematurity was defined as birth after a gestation period shorter than 37 weeks. Breakthrough cases were defined as invasive pneumococcal disease caused by a PCV13 serotype that occurred at least 14 days after the infant received a PCV13 dose; all other known serotypes were categorized as non-PCV13 serotypes.

Incidence of invasive pneumococcal disease was nearly 3-fold higher in premature infants compared with infants born at term (incidence rate ratio [IRR] 2.87; P <.001). In preterm infants born at < 28 weeks gestation, the incidence was almost 9-fold higher than in term infants (IRR, 8.8; P <.001). Of all study cases, 454 reported serotyped isolates, in which 369 cases (71.4%) were caused by non-PCV13 serotypes and 85 cases (16.4%) were caused by PCV13 serotypes. Overall, 31 infant deaths were recorded, resulting in a case fatality rate of 6.2% (95% CI, 4.3%-8.6%). The case fatality rate did not differ between preterm and term infants (P =.62). Among all infant deaths, 5 were associated with PCV13 serotypes and 18 were associated with non-PCV13 serotypes.

One limitation to the study was that the patient's general practitioner was responsible for completing the surveillance questionnaire, therefore there is a lack of clinical information on presenting symptoms, laboratory studies, sequelas, and exact prematurity status.

Infants born prematurely, and therefore with low birth weights, have an approximate 1.6-2.6-fold increased risk of acquiring invasive pneumococcal disease than term infants for both PCV13 and non-PCV13 serotypes. Increased risk was also positively correlated with degree of prematurity, but decreased with postnatal age. The investigators of the study suggested that primary vaccination schedules should consider the risk associated with preterm infant response to PCVs.

Multiple authors declare associations with the pharmaceutical industry. Please see original reference for a full list of authors' disclosures.

Reference                    

Kent A, Makwana A, Sheppard CL, et al. Invasive pneumococcal disease in UK children under 1 year of age in the post-PCV13 era: what are the risks now? [published online October 9, 2018]. Clin Infect Dis. doi:10.1093/cid/ciy842/5114360

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