Optimal Timing of Immunization Against Pertussis During Pregnancy
Notice bibliographique
Résumé
To the Editor—We read with interest Eberhardt et al's recent study reporting that immunization of pregnant women with tetanus-diphtheria-acellular pertussis (Tdap) during 13–25 gestational weeks (GWs) is associated with higher cord anti–pertussis toxin (PT) and filamentous hemagglutinin (FHA) immunoglobulin G (IgG) geometric mean concentrations (GMCs) and higher expected infant seropositivity rate compared with immunization beyond 26 GWs [1]. These findings are robust and timely given the recognized challenge of protecting young infants from pertussis disease. Moreover, although Eberhardt et al's results support our previous findings that immunization with Tdap during the early third trimester resulted in higher cord anti-PT and FHA IgG GMCs as compared to immunization during the late third trimester [2], several issues are worthy of further discussion. First, it remains to be determined if Tdap immunization in early pregnancy is associated with higher vaccine-specific IgG transfer efficiency compared with immunization later in pregnancy. The predominant IgG transplacental transfer occurs during the third trimester of pregnancy via the neonatal Fc receptor [3]. The efficiency of vaccine-specific IgG transplacental transfer corresponds to the cord-maternal ratio (CMR) of vaccine-specific antibody levels at delivery [4], rather than the cord absolute antibody levels. Several factors, including the concentration of total and vaccine-specific IgG in the maternal sera [4, 5], affect the efficiency of transfer across the placenta. Our previous data revealed that immunization during 27–30 GWs is associated with a significantly higher CMR of anti-PT, FHA, and pertactin IgG compared with immunization during 31–36 GWs [2]. Thus, data on maternal pertussis antibody levels at delivery are of great interest to enhance our understanding of the efficiency of pertussis-specific IgG transplacental transfer. Second, it is yet to be determined whether cord pertussis antibody levels measured at delivery are the result of cumulative transplacental transfer of antibodies during gestation or limited to the transfer that occurs mainly in close proximity to delivery. Earlier studies showed that maternally derived IgG levels in the fetal blood increase as gestation advances [3]. Notably, the amount of maternally derived pertussis antibodies in fetal blood is thought to be affected by the established adult's pertussis antibodies’ half-life; specifically, 36 days for anti-PT IgG and 40 days for anti-FHA IgG [6], with comparable data on infants yet to be established [7]. As such, maternally derived pertussis-specific antibodies accrued in fetal blood during early pregnancy following immunization in early gestation do not assure higher cord pertussis antibody levels at term delivery compared with immunization later in pregnancy, and in fact, their contribution to the total pertussis antibodies may be minimal. Finally, although anti-PT IgG >5 EU/mL is assumed as the seropositivity cutoff [1], the minimal protective level of pertussis-specific antibodies at delivery required to confer protection from pertussis disease in infants remains unknown. What is established is that higher pertussis antibody levels are associated with enhanced clinical protection from disease [8–10]. Thus, additional studies exploring the effect of the timing of Tdap immunization during pregnancy on the clinical protection of young infants from pertussis disease should be undertaken. Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential onflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
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Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,021 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,017 | 0,016 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,002 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».