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Importance Maternal immunization with tetanus toxoid and reduced diphtheria toxoid acellular pertussis (Tdap) vaccine could prevent infant pertussis. The effect of vaccine-induced maternal antibodies on infant responses to diphtheria and tetanus toxoids acellular pertussis (DTaP) immunization is unknown. Objective To evaluate the safety and immunogenicity of Tdap immunization during pregnancy and its effect on infant responses to DTaP. Design, Setting and Participants Phase I, randomized, double-masked, placebo-controlled clinical trial conducted in private (Houston) and academic (Durham, Seattle) obstetric practices from 2008 to 2012. Forty eight healthy 18–45 year-old pregnant women received Tdap (n=33) or placebo (n=15) at 30–32 weeks’ gestation with cross-over Tdap immunization postpartum. Interventions Tdap vaccination at 30–32 weeks’ gestation or post-partum. Outcome Measures Primary: Maternal and infant adverse events, pertussis illness and infant growth and development (Bayley-III screening test) until 13 months of age. Secondary: Antibody concentrations in pregnant women before and 4 weeks after Tdap immunization or placebo, at delivery and 2 months postpartum, and in infants at birth, 2 months, and after the third (7 months) and fourth (13 months) doses of DTaP. Results All participants delivered healthy newborns. No Tdap-associated serious adverse events occurred in women or infants. Injection site reactions after Tdap immunization were reported in 78.8% (95% CI: 61.1%, 91.0%) and 80% (CI: 51.9%, 95.7%) pregnant and postpartum women, respectively. Injection site pain was the predominant symptom. Systemic symptoms were reported in 36.4% (CI: 20.4%, 54.9%) and 73.3% (CI: 44.9%, 92.2%) pregnant and postpartum women, respectively. Malaise and myalgia were most common. Growth and development were similar in both infant groups. No cases of pertussis occurred. Significantly higher concentrations of pertussis antibodies were measured at delivery in women who received Tdap during pregnancy and in their infants at birth and at age 2 months when compared to infants of women immunized postpartum. Antibody responses in infants of Tdap recipients during pregnancy were modestly lower after 3 DTaP doses, but not different following the fourth dose. Conclusions and Relevance This preliminary safety assessment did not find an increased risk of adverse events among women who received Tdap vaccine at 30–32 weeks’ gestation or their infants. Maternal immunization with Tdap resulted in high concentrations of pertussis antibodies in infants during the first 2 months of life and did not substantially alter infant responses to DTaP. Further research is needed to provide definitive evidence of the safety and efficacy of Tdap vaccination during pregnancy. Trial Registration ClinicalTrials.gov, study identifier: NCT00707148. URL: http://www.clinicaltrials.gov

Severe acute respiratory syndrome coronavirus 2 related disease (COVID-19) is now responsible for one of the most challenging and concerning pandemics. By August 2020, there were almost 20 million confirmed cases worldwide and well over half-million deaths. Since there is still no effective treatment or vaccine, non-pharmaceutical interventions have been implemented in an attempt to contain the spread of the virus. During times of quarantine, immunization practices in all age groups, especially routine childhood vaccines, have also been interrupted, delayed, re-organized, or completely suspended. Numerous highincome as well as low-and middle-income countries are now experiencing a rapid decline in childhood immunization coverage rates. We will, inevitably, see serious consequences related to suboptimal control of vaccine-preventable diseases (VPDs) in children concurrent with or following the pandemic. Routine pediatric immunizations of individual children at clinics, mass vaccination campaigns, and surveillance for VPDs must continue as much as possible during pandemic.

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BACKGROUND: Respiratory syncytial virus (RSV) is a major cause of hospitalized acute respiratory illness (ARI) among young children. With RSV vaccines and immunoprophylaxis agents in clinical development, we sought to update estimates of US pediatric RSV hospitalization burden.METHODS: Children ,5 years old hospitalized for ARI were enrolled through active, prospective, population-based surveillance from November 1, 2015, to June 30, 2016, at 7 US pediatric hospital sites. Clinical information was obtained from parent interviews and medical records. Midturbinate nasal and throat flocked swabs were collected and tested for RSV by using molecular diagnostic assays at each site. We conducted descriptive analyses and calculated population-based rates of RSV-associated hospitalizations.RESULTS: Among 2969 hospitalized children included in analyses, 1043 (35%) tested RSVpositive; 903 (87%) children who were RSV-positive were ,2 years old, and 526 (50%) were ,6 months old. RSV-associated hospitalization rates were 2.9 per 1000 children ,5 years old and 14.7 per 1000 children ,6 months old; the highest age-specific rate was observed in 1-month-old infants (25.1 per 1000). Most children who were infected with RSV (67%) had no underlying comorbid conditions and no history of preterm birth.CONCLUSIONS: During the 2015-2016 season, RSV infection was associated with one-third of ARI hospitalizations in our study population of young children. Hospitalization rates were highest in infants ,6 months. Most children who were RSV-positive had no history of prematurity or underlying medical conditions, suggesting that all young children could benefit from targeted interventions against RSV.WHAT'S KNOWN ON THIS SUBJECT: Respiratory syncytial virus (RSV) infection is a major cause of hospitalization among young children. The US pediatric burden of hospitalized RSV is substantial, with the most recent prospective populationbased estimates of burden coming from 3 counties in 2000-2005.WHAT THIS STUDY ADDS: During 2015-2016, prospective population-based surveillance over a broader geographic area detected RSV in one-third of acute respiratory illness hospitalizations in our study population of young US children and yielded updated burden estimates that should help inform RSV-specific intervention strategies.

Despite efficient placental transfer, low maternal pertussis antibody levels and their rapid decay in infant sera leave infants with little humoral protection against pertussis. These data support the rationale for maternal or neonatal immunization, with acellular pertussis vaccines, to prevent life-threatening pertussis in early infancy.

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