Deshayne B. Fell (Canada)
UNIVERSITY OF OTTAWA AND CHILDREN'S HOSPITAL OF EASTERN ONTARIO RESEARCH INSTITUTE School of Epidemiology and Public HealthAuthor Of 3 Presentations
EXAMINING THE RELATIONSHIP BETWEEN RESPIRATORY SYNCYTIAL VIRUS, INFLUENZA, AND ROTAVIRUS SEASONS' TIMING AND SEVERITY, AND INFANT AGE AT VIRAL SEASONS' PEAKS, WITH SUBSEQUENT CHILDHOOD ASTHMA
Abstract
Backgrounds:
Most infants are exposed to respiratory syncytial virus (RSV) in the first year of life. Studies have observed an association between severe RSV infection and asthma, yet it is unclear if this relationship is causal or due to underlying factors that increase susceptibility to both conditions. One study partially mitigated the influence of these factors by examining the relationship between infant age at winter virus peak and subsequent asthma. We extended this approach by examining infant age at RSV, influenza, and rotavirus peaks, as well as proxies for the timing and severity of RSV, influenza, and rotavirus seasons, and their relationships with subsequent incidence of childhood asthma.
Methods
We analyzed province-wide administrative data for 1,437,731 infants born in Ontario, Canada from 2002-2013. We ascertained RSV, influenza, and rotavirus hospitalizations by 1 year and asthma by 5 years of age using inpatient/outpatient ICD-9/10 codes. We used regression models to investigate: (1) infant age in the calendar week with highest incidence of hospitalization for each virus and subsequent asthma (unit of analysis infant); (2) incidence of RSV-, influenza-, and rotavirus-related hospitalizations by 1 year and asthma by 5 years (unit of analysis calendar week of birth).
Results:
We observed highest likelihood of subsequent asthma at infant ages of approximately 13-, 11-, and 16-weeks during RSV, influenza, and rotavirus peaks, respectively. We observed apparent seasonal variation in childhood asthma by infant week of birth. The relationship between RSV seasonal variation and asthma appeared small in magnitude, while an unexpected relationship between rotavirus seasonal variation and asthma emerged (Figure).
Conclusions/Learning Points:
We find limited evidence in support of a causal relationship between RSV and asthma, and suggest further investigation of other mechanisms, including underlying seasonal characteristics.
EFFECTIVENESS OF INFLUENZA VACCINATION DURING PREGNANCY ON LABORATORY-CONFIRMED SEASONAL INFLUENZA AMONG INFANTS UNDER 6 MONTHS OF AGE IN ONTARIO
Abstract
Backgrounds:
Despite high-quality evidence from randomized clinical trials conducted in low-middle income countries showing efficacy of influenza vaccination during pregnancy against influenza infection among infants <6 months of age, assessments of effectiveness in settings with different influenza seasonality and across multiple seasons are limited.
Methods
We conducted a test-negative study using population-based Ontario laboratory data to identify all influenza virus tests (in any clinical setting) among infants <6 months of age during 9 influenza seasons (2010-11 to 2018-19). These data were linked with health administrative data to ascertain information on maternal-infant dyads, including whether women had been vaccinated against influenza during pregnancy. Vaccine effectiveness (VE) was estimated from the adjusted odds ratio for vaccination, computed using logistic regression with adjustment for maternal age, infant age at test, season of conception, prenatal care adequacy, neighbourhood income, and influenza season. Women who received influenza vaccination less than 14 days prior to obstetric delivery or received the previous season’s vaccine were treated as unvaccinated.
Results:
Among 23,806 infants <6 months of age who were tested for influenza virus, 1,783 (7.5%) tested positive. Overall, 2,168 (9.1%) of infants were born to women vaccinated against influenza during pregnancy; 1,708 (7.2%) remained when those vaccinated less than 14 days before delivery or with the previous season’s influenza vaccine were reclassified as unvaccinated. Across seasons, the adjusted effectiveness of influenza vaccination during pregnancy against laboratory-confirmed infant influenza infection prior to 6 months of age was 64% (95% confidence interval: 51% to 74%).
Conclusions/Learning Points:
Since infants <6 months are at high risk for serious influenza-related illness, but not eligible for influenza vaccination, immunization during pregnancy is an effective strategy for protecting young infants during their first influenza season.
COVID-19 VACCINATION DURING PREGNANCY AND RISK OF PRETERM BIRTH, SMALL-FOR-GESTATIONAL-AGE BIRTH, AND STILLBIRTH IN ONTARIO, CANADA
Abstract
Backgrounds:
Emerging evidence suggests COVID-19 vaccination during pregnancy may reduce risk of newborn SARS-CoV-2 infection; however, safety concerns remain a potential obstacle to achieving high coverage during pregnancy. This study aimed to assess the risk of preterm birth, small-for-gestational-age (SGA) birth, and stillbirth after COVID-19 vaccination during pregnancy.
Methods:
We used provincial databases in Ontario, Canada to identify all live and stillbirths ≥20 weeks’ gestation (birth registry), linked to COVID-19 vaccination data (vaccine registry) for May 1 to November 30, 2021. Using Cox regression, we estimated adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for preterm birth, SGA birth (<10th percentile), and stillbirth treating COVID-19 vaccination as a time-varying exposure. Models were adjusted for calendar time, COVID-19 illness, sociodemographic factors, health behaviours, and pregnancy-related factors.
Results:
Among 69,650 births, 33,295 (47.8%) were born to individuals who received ≥1 dose of COVID-19 vaccine during pregnancy. The incidence of preterm birth was 6.5% among those who received ≥1 dose of COVID-19 vaccine during pregnancy and 7.0% among unvaccinated. The risk of preterm birth was not associated with COVID-19 vaccination during pregnancy (adjusted HR [aHR] 0.96, 95% CI, 0.91 to 1.02), nor was spontaneous preterm birth or very preterm birth (<32 weeks). Similarly, there was no increased risk of SGA birth in vaccinated vs. unvaccinated individuals (8.7% vs. 9.2%; aHR, 1.00; 95% CI, 0.95 to 1.05) or stillbirth (1.6 vs. 2.8 per 1000; aHR, 0.64; 95% CI, 0.46 to 0.90). Results did not differ by trimester of vaccination, mRNA vaccine product, or number of doses received during pregnancy.
Conclusions/Learning Points:
In this large population, COVID-19 vaccination during pregnancy was not associated with a higher risk of preterm birth, SGA birth, or stillbirth.
Presenter of 2 Presentations
EFFECTIVENESS OF INFLUENZA VACCINATION DURING PREGNANCY ON LABORATORY-CONFIRMED SEASONAL INFLUENZA AMONG INFANTS UNDER 6 MONTHS OF AGE IN ONTARIO
Abstract
Backgrounds:
Despite high-quality evidence from randomized clinical trials conducted in low-middle income countries showing efficacy of influenza vaccination during pregnancy against influenza infection among infants <6 months of age, assessments of effectiveness in settings with different influenza seasonality and across multiple seasons are limited.
Methods
We conducted a test-negative study using population-based Ontario laboratory data to identify all influenza virus tests (in any clinical setting) among infants <6 months of age during 9 influenza seasons (2010-11 to 2018-19). These data were linked with health administrative data to ascertain information on maternal-infant dyads, including whether women had been vaccinated against influenza during pregnancy. Vaccine effectiveness (VE) was estimated from the adjusted odds ratio for vaccination, computed using logistic regression with adjustment for maternal age, infant age at test, season of conception, prenatal care adequacy, neighbourhood income, and influenza season. Women who received influenza vaccination less than 14 days prior to obstetric delivery or received the previous season’s vaccine were treated as unvaccinated.
Results:
Among 23,806 infants <6 months of age who were tested for influenza virus, 1,783 (7.5%) tested positive. Overall, 2,168 (9.1%) of infants were born to women vaccinated against influenza during pregnancy; 1,708 (7.2%) remained when those vaccinated less than 14 days before delivery or with the previous season’s influenza vaccine were reclassified as unvaccinated. Across seasons, the adjusted effectiveness of influenza vaccination during pregnancy against laboratory-confirmed infant influenza infection prior to 6 months of age was 64% (95% confidence interval: 51% to 74%).
Conclusions/Learning Points:
Since infants <6 months are at high risk for serious influenza-related illness, but not eligible for influenza vaccination, immunization during pregnancy is an effective strategy for protecting young infants during their first influenza season.
COVID-19 VACCINATION DURING PREGNANCY AND RISK OF PRETERM BIRTH, SMALL-FOR-GESTATIONAL-AGE BIRTH, AND STILLBIRTH IN ONTARIO, CANADA
Abstract
Backgrounds:
Emerging evidence suggests COVID-19 vaccination during pregnancy may reduce risk of newborn SARS-CoV-2 infection; however, safety concerns remain a potential obstacle to achieving high coverage during pregnancy. This study aimed to assess the risk of preterm birth, small-for-gestational-age (SGA) birth, and stillbirth after COVID-19 vaccination during pregnancy.
Methods:
We used provincial databases in Ontario, Canada to identify all live and stillbirths ≥20 weeks’ gestation (birth registry), linked to COVID-19 vaccination data (vaccine registry) for May 1 to November 30, 2021. Using Cox regression, we estimated adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for preterm birth, SGA birth (<10th percentile), and stillbirth treating COVID-19 vaccination as a time-varying exposure. Models were adjusted for calendar time, COVID-19 illness, sociodemographic factors, health behaviours, and pregnancy-related factors.
Results:
Among 69,650 births, 33,295 (47.8%) were born to individuals who received ≥1 dose of COVID-19 vaccine during pregnancy. The incidence of preterm birth was 6.5% among those who received ≥1 dose of COVID-19 vaccine during pregnancy and 7.0% among unvaccinated. The risk of preterm birth was not associated with COVID-19 vaccination during pregnancy (adjusted HR [aHR] 0.96, 95% CI, 0.91 to 1.02), nor was spontaneous preterm birth or very preterm birth (<32 weeks). Similarly, there was no increased risk of SGA birth in vaccinated vs. unvaccinated individuals (8.7% vs. 9.2%; aHR, 1.00; 95% CI, 0.95 to 1.05) or stillbirth (1.6 vs. 2.8 per 1000; aHR, 0.64; 95% CI, 0.46 to 0.90). Results did not differ by trimester of vaccination, mRNA vaccine product, or number of doses received during pregnancy.
Conclusions/Learning Points:
In this large population, COVID-19 vaccination during pregnancy was not associated with a higher risk of preterm birth, SGA birth, or stillbirth.