JAMA Pediatrics - study cautions about vaccination risks for low birth weight infants
A study in the June issue of the Journal of the American Medical Association (JAMA) Pediatrics revealed that extremely low birth weight infants are more likely to suffer adverse effects after routine vaccinations, including breathing difficulties, slowed heart rate, fever, the need for painful diagnosistic procedures, and more.
The study, Adverse Events After Routine Immunization of Extremely Low-Birth-Weight Infants, appears in the June 2015 issue JAMA Pediatrics.
The authors examined the records of almost 14,000 extremely low birth weight infants in neonatal intensive care units. They wrote:
Immunization of extremely low-birth-weight (ELBW) infants in the neonatal intensive care unit (NICU) is associated with adverse events, including fever and apnea or bradycardia, in the immediate postimmunization period. These adverse events present a diagnostic dilemma for physicians, leading to the potential for immunization delay and sepsis evaluations.
The study found that adverse events greatly increased after vaccination. The authors concluded:
All ELBW infants in the NICU had an increased incidence of sepsis evaluations and increased respiratory support and intubation after routine immunization.
The adverse effects noticed in the three day period directly after vaccination included:
Fever
The need for sepsis (blood infection) evaluations
Apnea (cessation of breathing, generally for 20 seconds or more)
Bradycardia (slowed heart rate)
Need for intubation (insertion of breathing tubes)
Need for respiratory support.
The researchers were concerned that infants tend to suffer adverse events after vaccination, such as slowed or stopped breathing, fever and slowed heart rate, and that doctors may also confuse these symptoms with sepsis, leading to the need for more painful procedures and unnecessary antiobiotics for these at-risk infants. They wrote:
However, the immunization of extremely low-birth-weight (ELBW; birth weight ≤1000 g) infants has been associated with adverse events, including fever and adverse cardiorespiratory events, such as apnea and bradycardia... Fever in ELBW infants after immunization can often lead to additional workup to rule out true sepsis, including collection of blood and urine cultures, and exposure to empirical antibiotic therapy. The risks of additional antibiotic use, exposing the infant to painful procedures, and the withholding of enteral feedings must be weighed against the risk of missing true sepsis in an ELBW infant.
The findings of the study included:
The incidence of sepsis evaluations increased from 5.4 per 1000 patient-days before vaccination to 19.3 per 1000 patient-days after vaccinations.
Of the 235 sepsis evaluations performed in the pre-vaccination period, 5 (2.1%) yielded a positive blood culture result compared with 39 (3.8%) of 1035 evaluations performed after vaccination.
The need for increased respiratory support increased from 6.6 per 1000 patient-days before vaccination to 14.0 per 1000 patient-days after vaccination.
The need for intubation increased from 2.0 per 1000 patient-days before vaccination to 3.6 per 1000 patient-days after vaccination.
Infants who were born at 23 to 24 weeks gestation had a higher risk of sepsis evaluation and intubation after vaccination.
A prior history of sepsis was associated with higher risk of sepsis evaluation after vaccination.
The incidence of adverse events was similar across vaccination types, including combination vaccines when compared with single-dose vaccines.
The researchers studied a total of 13,926 infants who received a total of 48,853 vaccinations; 12,703 infants (91.2%) received 3 or more vaccinations.
Five infants died in the three days following vaccinations. The researchers reported:
There were 5 deaths in the postimmunization period. Three of the 5 infants who died in the 3 days after immunization had a diagnosis associated with death available in the data set; 1 infant had a bowel perforation, 1 infant had necrotizing enterocolitis and presumed sepsis, and 1 infant had pneumonia and respiratory failure.
The researchers, who believe strongly in the importance of vaccinations, also discussed risks with specific vaccines and combination vaccines for extremely low birth weight infants:
Apnea and bradycardia are also commonly observed adverse events in the postimmunization period. The DTaP-containing vaccines have been of particular concern because the whole-cell pertussis vaccine has been cited as causing apnea and bradycardia in 7% of preterm infants, and more recently, apnea and bradycardia have been observed after immunization with the acellular pertussis vaccine component.
Regarding the use of combination vaccines, a 2007 study of the hexavalent DTaP, IPV, HiB, and HepB vaccine found that apnea and/or bradycardia occurred in 11% of study infants, demonstrating slightly higher rates of adverse events compared with single-dose vaccines.
More recently, a retrospective study in 2008 of 64 infants who received the combination DTaP, IPV, and HiB vaccine and the 7-valent pneumococcal conjugate vaccine found that 25% of study infants had clinically significant apnea and bradycardia.
These findings are especially important for parents and doctors to keep in mind when making vaccination decisions for infants who are already medically fragile, and demonstrate a need for further research into how to best care for extremely low birth weight infants.
You can read the entire study and view the graphs of adverse incidents here.
