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Association of reactions after consecutive acellular or whole-cell pertussis vaccine immunizations
M A Deloria1, W C Blackwelder, M D Decker
1Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892, USA.
Insights
Infants receiving whole-cell pertussis vaccines (WCV) experienced more adverse reactions than those receiving acellular pertussis vaccines (APV). Repeated reactions were more common after initial reactions for both vaccine types, but absolute risks were lower with APV.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Pertussis vaccines, including whole-cell (DTP) and acellular (DTaP) formulations, are critical for infant immunization.
- Understanding the frequency and patterns of adverse reactions is essential for vaccine safety monitoring.
Purpose of the Study:
- To compare the incidence of adverse reactions following initial and subsequent immunizations in infants receiving either DTaP or DTP vaccines.
- To evaluate the relative risk of repeated reactions after prior adverse events for both vaccine types.
Main Methods:
- A cohort of 2127 infants receiving primary immunization at 2, 4, and 6 months was analyzed.
- Common adverse reactions (fever, redness, swelling, pain, fussiness, etc.) were recorded within 48 hours post-vaccination.
- Data from at least two consecutive immunizations were available for 357 DTP recipients and 1770 DTaP recipients.
Main Results:
- Adverse reactions were 1.5 to 8 times more likely in DTP recipients if the same reaction occurred previously.
- Both initial and repeated reactions were less frequent in DTaP recipients compared to DTP recipients.
- For both vaccine types, the risk of a repeated reaction was higher than the risk of an initial reaction (2.5 to 24 times higher in DTaP recipients).
Conclusions:
- Infants who experience a reaction after one immunization are more likely to experience the same reaction after subsequent immunizations, regardless of vaccine type (DTP or DTaP).
- The absolute risk of repeated adverse reactions was consistently lower for infants receiving the DTaP vaccine compared to the DTP vaccine.
Objective:
To evaluate the relative frequency of adverse reactions after initial and subsequent immunizations among infants receiving primary immunization with acellular (DTaP) or whole-cell (DTP) pertussis vaccine with diphtheria and tetanus combined.
Methods:
We examined the occurrence of common reactions in 2127 infants within 48 hours after immunization at 2, 4, and 6 months with one of 13 DTaP or with Lederle DTP (WCL). Data on at least two consecutive immunizations were available for 357 WCL recipients and 1770 DTaP recipients. For these analyses, reactions evaluated included fever of 100.4 degrees F (38 degrees C) or greater, redness of 21 mm or larger, swelling of 21 mm or larger, moderate or severe pain, moderate or severe fussiness, loss of appetite, drowsiness, and vomiting.
Results:
With one exception, reactions were approximately 1.5 to 8 times more likely to occur in WCL recipients if the same reaction had been observed at the previous immunization (the single exception was redness after the second immunization). Both initial and repeated reactions were less likely in DTaP than in WCL recipients. As with WCL recipients, risks of repeated reactions in DTaP recipients were higher than the risks of initial reactions (from 2.5 to 24 times as high).
Conclusion:
Reactions after a second or third immunization with either WCL or DTaP vaccine are more likely to occur in infants who had the same reaction after the preceding immunization. Absolute risks of repeated reactions tended to be lower after DTaP vaccine than after the WCL vaccine.