Estimated Effectiveness of Postpartum Maternal Messenger RNA COVID-19 Vaccination Against Delta and Omicron SARS-CoV-2 Infection and Hospitalization in Infants Younger Than 6 Months.

This case-control study estimates the effectiveness of maternal postpartum messenger RNA (mRNA) COVID-19 vaccination against Delta and Omicron SARS-CoV-2 infection and hospitalization in infants younger than 6 months.

Sociodemographic Differences in Physician-Based Mental Health and Virtual Care Utilization and Uptake of Virtual Care Among Children and Adolescents During the COVID-19 Pandemic in Ontario, Canada: A Population-Based Study.

OBJECTIVE: We sought to evaluate the relationship between social determinants of health and physician-based mental healthcare utilization and virtual care use among children and adolescents in Ontario, Canada, during the COVID-19 pandemic. METHODS: This population-based repeated cross-sectional study of children and adolescents (3-17 years; N = 2.5 million) used linked health and demographic administrative data in Ontario, Canada (2017-2021). Multivariable Poisson regressions with generalized estimating equations compared rates of outpatient physician-based mental healthcare use during the first year of the COVID-19 pandemic with expected rates based on pre-COVID patterns. Analyses were conducted by socioeconomic status (material deprivation quintiles of the Ontario Marginalization index), urban/rural region of residence, and immigration status. RESULTS: Overall, pediatric physician-based mental healthcare visits were 5% lower than expected (rate ratio [RR] = 0.95, 95% confidence interval [CI], 0.92 to 0.98) among those living in the most deprived areas in the first year of the pandemic, compared with the least deprived with 4% higher than expected rates (RR = 1.04, 95% CI, 1.02 to 1.06). There were no differences in overall observed and expected visit rates by region of residence. Immigrants had 14% to 26% higher visit rates compared with expected from July 2020 to February 2021, whereas refugees had similarly observed and expected rates. Virtual care use was approximately 65% among refugees, compared with 70% for all strata. CONCLUSION: During the first year of the pandemic, pediatric physician-based mental healthcare utilization was higher among immigrants and lower than expected among those with lower socioeconomic status. Refugees had the lowest use of virtual care. Further work is needed to understand whether these differences reflect issues in access to care or the need to help inform ongoing pandemic recovery planning.

Maternal mRNA covid-19 vaccination during pregnancy and delta or omicron infection or hospital admission in infants: test negative design study.

OBJECTIVE: To estimate the effectiveness of maternal mRNA covid-19 vaccination during pregnancy against delta and omicron severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and hospital admission in infants. DESIGN: Test negative design study. SETTING: Community and hospital testing in Ontario, Canada. PARTICIPANTS: Infants younger than six months of age, born between 7 May 2021 and 31 March 2022, who were tested for SARS-CoV-2 between 7 May 2021 and 5 September 2022. INTERVENTION: Maternal mRNA covid-19 vaccination during pregnancy. MAIN OUTCOME MEASURES: Laboratory confirmed delta or omicron infection or hospital admission of the infant. Multivariable logistic regression estimated vaccine effectiveness, with adjustments for clinical and sociodemographic characteristics associated with vaccination and infection. RESULTS: 8809 infants met eligibility criteria, including 99 delta cases (4365 controls) and 1501 omicron cases (4847 controls). Infant vaccine effectiveness from two maternal doses was 95% (95% confidence interval 88% to 98%) against delta infection and 97% (73% to 100%) against infant hospital admission due to delta and 45% (37% to 53%) against omicron infection and 53% (39% to 64%) against hospital admission due to omicron. Vaccine effectiveness for three doses was 73% (61% to 80%) against omicron infection and 80% (64% to 89%) against hospital admission due to omicron. Vaccine effectiveness for two doses against infant omicron infection was highest with the second dose in the third trimester (53% (42% to 62%)) compared with the first (47% (31% to 59%)) or second (37% (24% to 47%)) trimesters. Vaccine effectiveness for two doses against infant omicron infection decreased from 57% (44% to 66%) between birth and eight weeks to 40% (21% to 54%) after 16 weeks of age. CONCLUSIONS: Maternal covid-19 vaccination with a second dose during pregnancy was highly effective against delta and moderately effective against omicron infection and hospital admission in infants during the first six months of life. A third vaccine dose bolstered protection against omicron. Effectiveness for two doses was highest with maternal vaccination in the third trimester, and effectiveness decreased in infants beyond eight weeks of age.

School Reopening And COVID-19 In The Community: Evidence From A Natural Experiment In Ontario, Canada.

In December 2020, Ontario, Canada, entered a provincewide shutdown to mitigate COVID-19 transmission. A regionalized approach was taken to reopen schools throughout early 2021 without any other opening of the economy, offering a unique natural experiment to estimate the impact of school reopening on community transmission. Estimated increases of 0.07, 0.08, 0.07, and 0.13 percentage points in community COVID-19 case growth rates occurred 11-15, 16-20, 21-25, and 26-30 days, respectively, after schools reopened. Although small, these changes were particularly evident among children younger than age fourteen, increased over time, and were greater when lag periods were considered, which points to a likely causal effect between in-person classes and a small increase in transmission. These findings suggest that although additional COVID-19 cases are to be expected after the reopening of schools, these risks may be manageable with sufficient, layered mitigation policies.

Pivoting data and analytic capacity to support Ontario's COVID-19 response.

Introduction: Health care systems have faced unprecedented challenges due to the COVID-19 pandemic. Access to timely population-based data has been vital to informing public health policy and practice. Methods: We describe how ICES, an independent not-for-profit research and analytic institute in Ontario, Canada, pivoted existing research infrastructure and engaged health system stakeholders to provide near real-time population-based data and analytics to support Ontario's COVID-19 pandemic response. Results: Since April 2020, ICES provided the Ontario COVID-19 Provincial Command Table and public health partners with regular and ad hoc reports on SARS-CoV-2 testing and COVID-19 vaccine coverage. These reports: 1) helped identify congregate care/shared living settings that needed testing and prevention efforts early in the pandemic; 2) provided early indications of inequities in testing and infection in marginalized neighbourhoods, including areas with higher proportions of immigrants and visible minorities; 3) identified areas with high test positivity, which helped Public Health Units target and evaluate prevention efforts; and 4) contributed to altering the province's COVID-19 vaccine roll-out strategy to target high-risk neighbourhoods and helping Public Health Units and community organizations plan local vaccination programs. In addition, ICES is a key component of the Ontario Health Data Platform, which provides scientists with data access to conduct COVID-19 research and analyses. Discussion and Conclusion: ICES was well-positioned to provide rapid analyses for decision-makers to respond to the evolving public health emergency, and continues to contribute to Ontario's pandemic response by providing timely, relevant reports to health system stakeholders and facilitating data access for externally-funded COVID-19 research.

Acute Care Visits for Assault and Maltreatment Before vs During the COVID-19 Pandemic in Ontario, Canada

This cross-sectional study compares rates of emergency department visits and hospitalizations for assault and maltreatment by age category and sex in Ontario, Canada, before vs during the COVID-10 pandemic.

Utilization of Physician-Based Mental Health Care Services Among Children and Adolescents Before and During the COVID-19 Pandemic in Ontario, Canada.

IMPORTANCE: Public health measures to reduce the spread of COVID-19 have heightened distress among children and adolescents and contributed to a shift in delivery of mental health care services. OBJECTIVES: To measure and compare physician-based outpatient mental health care utilization before and during the COVID-19 pandemic and quantify the extent of uptake of virtual care delivery. DESIGN, SETTING, AND PARTICIPANTS: Population-based repeated cross-sectional study using linked health and administrative databases in Ontario, Canada. All individuals aged 3 to 17 years residing in Ontario from January 1, 2017, to February 28, 2021. EXPOSURES: Pre-COVID-19 period from January 1, 2017, to February 29, 2020, and post-COVID-19 onset from March 1, 2020, to February 28, 2021. MAIN OUTCOMES AND MEASURES: Physician-based outpatient weekly visit rates per 1000 population for mental health diagnoses overall and stratified by age group, sex, and mental health diagnostic grouping and proportion of virtual visits. Poisson generalized estimating equations were used to model 3-year pre-COVID-19 trends and forecast expected trends post-COVID-19 onset and estimate the change in visit rates before and after the onset of COVID-19. The weekly proportions of virtual visits were calculated. RESULTS: In a population of almost 2.5 million children and adolescents (48.7% female; mean [SD] age, 10.1 [4.3] years), the weekly rate of mental health outpatient visits was 6.9 per 1000 population. Following the pandemic onset, visit rates declined rapidly to below expected (adjusted relative rate [aRR], 0.81; 95% CI, 0.79-0.82) in April 2020 followed by a growth to above expected (aRR, 1.07; 95% CI, 1.04-1.09) by July 2020 and sustained at 10% to 15% above expected as of February 2021. Adolescent female individuals had the greatest increase in visit rates relative to expected by the end of the study (aRR, 1.26; 95% CI, 1.25-1.28). Virtual care accounted for 5.0 visits per 1000 population (72.5%) of mental health visits over the study period, with a peak of 5.3 visits per 1000 population (90.1%) (April 2020) and leveling off to approximately 70% in the latter months. CONCLUSIONS AND RELEVANCE: Physician-based outpatient mental health care in Ontario increased during the pandemic, accompanied by a large, rapid shift to virtual care. There was a disproportionate increase in use of mental health care services among adolescent female individuals. System-level planning to address the increasing capacity needs and to monitor quality of care with such large shifts is warranted.

Comparison of Self-harm or Overdose Among Adolescents and Young Adults Before vs During the COVID-19 Pandemic in Ontario.

Importance: Self-harm and deaths among adolescents and young adults are notably related to drug poisonings and suicide. With the emergence of the COVID-19 pandemic, there are projections about a greater likelihood of such events arising among adolescents and young adults. Objective: To evaluate the risk of self-harm, overdose, and all-cause mortality among adolescents and young adults during the COVID-19 pandemic. Design, Setting, and Participants: This population-based cohort study took place in Ontario, Canada, where a universal health care system captures all emergency department (ED) visits, hospitalizations, and deaths. The participants included all adolescents and young adults born in Ontario between 1990 and 2006, who were aged 14 to 24 years between March 1, 2018, and June 30, 2021. Exposures: The COVID-19 pandemic era (April 1, 2020 to June 30, 2021), relative to the 2 years preceding the pandemic (March 1, 2018 to February 28, 2020). Main Outcomes and Measures: ED encounters or hospitalizations for self-harm or overdose. A secondary outcome was self-harm, overdose, or all-cause mortality. Cause-specific hazard models to estimate hazard ratios (HR) and 95% CIs were used for the primary outcome. Follow-up started at March 1, 2018, or the individual's 14th birthday, whichever was later, and age was used as the time scale. Results: In this study, 1 690 733 adolescents and young adults (823 904 [51.3%] female participants) were included with a median (IQR) age of 17.7 (14.1-21.4) years at start of follow-up. After 4 110 903 person-years of follow-up, 6224 adolescents and young adults experienced the primary outcome of self-harm or overdose during the pandemic (39.7 per 10 000 person-years) vs 12 970 (51.0 per 10 000 person-years) prepandemic, with an HR of 0.78 (95% CI, 0.75-0.80). The risk of self-harm, overdose, or death was also lower during than before the pandemic (HR, 0.78; 95% CI, 0.76-0.81), but not all-cause mortality (HR, 0.95; 95% CI, 0.86-1.05). Conclusions and Relevance: Among adolescents and young adults, the initial 15-month period of the COVID-19 pandemic was associated with a relative decline in hospital care for self-harm or overdose.

Pediatric primary care in Ontario and Manitoba after the onset of the COVID-19 pandemic: a population-based study.

BACKGROUND: There were large disruptions to health care services after the onset of the COVID-19 pandemic. We sought to describe the extent to which pandemic-related changes in service delivery and access affected use of primary care for children overall and by equity strata in the 9 months after pandemic onset in Manitoba and Ontario. METHODS: We performed a population-based study of children aged 17 years or less with provincial health insurance in Ontario or Manitoba before and during the COVID-19 pandemic (Jan. 1, 2017-Nov. 28, 2020). We calculated the weekly rates of in-person and virtual primary care well-child and sick visits, overall and by age group, neighbourhood material deprivation level, rurality and immigrant status, and assessed changes in visit rates after COVID-19 restrictions were imposed compared to expected baseline rates calculated for the 3 years before pandemic onset. RESULTS: Among almost 3 million children in Ontario and more than 300 000 children in Manitoba, primary care visit rates declined to 0.80 (95% confidence interval [CI] 0.77-0.82) of expected in Ontario and 0.82 (95% CI 0.79-0.84) of expected in Manitoba in the 9 months after the onset of the pandemic. Virtual visits accounted for 53% and 29% of visits in Ontario and Manitoba, respectively. The largest monthly decreases in visits occurred in April 2020. Although visit rates increased slowly after April 2020, they had not returned to prerestriction levels by November 2020 in either province. Children aged more than 1 year to 12 years experienced the greatest decrease in visits, especially for well-child care. Compared to prepandemic levels, visit rates were lowest among rural Manitobans, urban Ontarians and Ontarians in low-income neighbourhoods. INTERPRETATION: During the study period, the pandemic contributed to rapid, immediate and inequitable decreases in primary care use, with some recovery and a substantial shift to virtual care. Postpandemic planning must consider the need for catch-up visits, and the long-term impacts warrant further study.

Acute mental health service use following onset of the COVID-19 pandemic in Ontario, Canada: a trend analysis.

BACKGROUND: The extent to which heightened distress during the COVID-19 pandemic translated to increases in severe mental health outcomes is unknown. We examined trends in psychiatric presentations to acute care settings in the first 12 months after onset of the pandemic. METHODS: This was a trends analysis of administrative population data in Ontario, Canada. We examined rates of hospitalizations and emergency department visits for mental health diagnoses overall and stratified by sex, age and diagnostic grouping (e.g., mood disorders, anxiety disorders, psychotic disorders), as well as visits for intentional self-injury for people aged 10 to 105 years, from January 2019 to March 2021. We used Joinpoint regression to identify significant inflection points after the onset of the pandemic in March 2020. RESULTS: Among the 12 968 100 people included in our analysis, rates of mental health-related hospitalizations and emergency department visits declined immediately after the onset of the pandemic (peak overall decline of 30% [hospitalizations] and 37% [emergency department visits] compared to April 2019) and returned to near prepandemic levels by March 2021. Compared to April 2019, visits for intentional self-injury declined by 33% and remained below prepandemic levels until March 2021. We observed the largest declines in service use among adolescents aged 14 to 17 years (55% decline in hospitalizations, 58% decline in emergency department visits) and 10 to 13 years (56% decline in self-injury), and for those with substance-related disorders (33% decline in emergency department visits) and anxiety disorders (61% decline in hospitalizations). INTERPRETATION: Contrary to expectations, the abrupt decline in acute mental health service use immediately after the onset of the pandemic and the return to near prepandemic levels that we observed suggest that changes and stressors in the first 12 months of the pandemic did not translate to increased service use. Continued surveillance of acute mental health service use is warranted.

Acute Care Visits for Eating Disorders Among Children and Adolescents After the Onset of the COVID-19 Pandemic.

PURPOSE: Anecdotal reports suggest a significant increase in acute presentations of eating disorders among children and adolescents. Our objective was to compare the rates of emergency department visits and hospitalizations for pediatric eating disorders before and during the first 10 months of the COVID-19 pandemic. METHODS: Using linked health administrative databases, we conducted a population-based repeated cross-sectional study of emergency department visits and hospitalizations for eating disorders among all children and adolescents aged 3-17 years, residing in Ontario, Canada. We defined the pre-COVID period from January 1, 2017, to February 29, 2020, and the post-COVID period from March 1, 2020, to December 26, 2020. Poisson generalized estimating equations were used to model 3-year pre-COVID trends to predict expected post-COVID trends and estimate the relative change from expected rates. RESULTS: In our population of almost 2.5 million children and adolescents, acute care visits for eating disorders increased immediately after the onset of the pandemic, reaching a 4-week peak annualized rate of 34.6 (emergency department visits) and 43.2 per 100,000 population (hospitalizations) in October 2020. Overall, we observed a 66% (adjusted relative rate: 1.66, 95% confidence interval: 1.41-1.96) and 37% (adjusted relative rate: 1.37, 95% confidence interval: 1.25-1.50) increase in risk for emergency department visit and hospitalization, respectively. CONCLUSIONS: Acute care visits for pediatric eating disorders increased significantly in Ontario after the onset of COVID-19 pandemic and remained well above expected levels during the first 10 months of the pandemic. Further research is needed to understand the social and neurobiological mechanisms underlying the observed changes in health system utilization.

Acute Care Visits for Assault and Maltreatment Before vs During the COVID-19 Pandemic in Ontario, Canada.

This cross-sectional study compares rates of emergency department visits and hospitalizations for assault and maltreatment by age category and sex in Ontario, Canada, before vs during the COVID-10 pandemic.

The Role of a Resilient Information Infrastructure in COVID-19 Vaccine Uptake in Ontario.

The COVID-19 pandemic has highlighted the need for a robust and nimble public health data infrastructure. ICES - a government-sponsored, independent, non-profit research institute in Ontario, Canada - functions as a key component of a resilient information infrastructure and an enabler of data co-production, contributing to Ontario's response to the COVID-19 pandemic as part of a learning health system. Linked data on the cumulative incidence of infection and vaccination at the neighbourhood level revealed disparate uptake between areas with low versus high risk of COVID-19. These data were leveraged by the government, service providers, media and the public to inform a more efficient and equitable vaccination strategy.