Invasive Pneumococcal Disease Epidemiology and Serotype Replacement After the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine in Ontario, Canada, 2007-2022.

Background: New vaccine products were recently authorized for protection against invasive pneumococcal disease (IPD) in Canada. Our aim was to determine age- and serotype-specific trends in IPD incidence and severity in Canada's largest province, Ontario. Methods: We included all confirmed IPD cases reported in Ontario and defined the pre-pneumococcal 13-valent conjugate vaccine (PCV13) era (01/2007 to 12/2010), post-PCV13 era (01/2011 to 12/2019), and coronavirus disease 2019 (COVID-19) pandemic era (01/2020 to 12/2022). We estimated incidence, hospitalization, and case fatality rate (CFR) by age. We grouped IPD cases by vaccine-specific serotypes (PCV13; PCV15-non-PCV13; PCV20-non-PCV13; PCV20-non-PCV15; polysaccharide 23-valent vaccine-non-PCV20; and non-vaccine-preventable [NVP]). We then compared incidence rates by age and serotype group in the pre- and post-PCV13 eras by calculating rate ratios (RRs) and their 95% CIs. Results: Incidence and hospitalizations declined from the pre- to post-PCV13 era in children aged <5 years (RR, 0.7; 95% CI, 0.6-0.8; and RR, 0.8; 95% CI, 0.7-0.9, respectively), but the CFR increased (1.4% to 2.3%). Other age groups saw smaller declines or more stable incidence rates across the years; hospitalizations increased in adults aged 50-64 years (RR, 1.2; 95% CI, 1.1-1.4) and ≥65 years (RR, 1.1; 95% CI, 1.0-1.1). For all ages, IPD cases and hospitalizations attributable to PCV13 serotypes declined, and those attributable to PCV15-non-PCV13, PCV20-non-PCV13, and NVP serotypes increased. IPD incidence declined during the COVID-19 era. Conclusions: IPD incidence and hospitalizations due to PCV13 serotypes decreased after PCV13 introduction but increased for other serotypes. Continued surveillance is required to evaluate changes to pneumococcal vaccination programs and ongoing changes to the distribution of IPD-causing serotypes.

Myocarditis or Pericarditis Events After BNT162b2 Vaccination in Individuals Aged 12 to 17 Years in Ontario, Canada.

Importance: The risk of myocarditis or pericarditis after COVID-19 messenger RNA vaccines varies by age and sex, and there is some evidence to suggest increasing risk with shorter intervals between dose 1 and 2 (ie, interdose interval). Objective: To estimate the incidence of reported myocarditis or pericarditis after BNT162b2 vaccine among adolescents and to describe the clinical information associated with these events. Design, Setting, and Participants: This was a population-based cohort study using passive vaccine safety surveillance data linked to the provincial COVID-19 vaccine registry. Included in the study were all adolescents aged 12 to 17 years in Ontario, Canada, who received 1 or more doses of BNT162b2 vaccine between December 14, 2020, and November 21, 2021, and reported an episode of myocarditis or pericarditis. Data were analyzed from December 15, 2021, to April 22, 2022. Exposure: Receipt of BNT162b2 (Comirnaty [Pfizer-BioNTech]) vaccine. Main Outcomes and Measure: Reported incidence of myocarditis or pericarditis meeting level 1 to 3 of the Brighton Collaboration case definition per 100 000 doses of BNT162b2 administered by age group (12-15 years vs 16-17 years), sex, dose number, and interdose interval. All clinical information associated with symptoms, health care usage, diagnostic test results, and treatment at the time of the acute event were summarized. Results: There were approximately 1.65 million doses of BNT162b2 administered and 77 reports of myocarditis or pericarditis among those aged 12 to 17 years, which met the inclusion criteria during the study period. Of the 77 adolescents (mean [SD] age, 15.0 [1.7] years; 63 male individuals [81.8%]), 51 (66.2%) developed myocarditis or pericarditis after dose 2 of BNT162b2. Overall, 74 individuals (96.1%) with an event were assessed in the emergency department, and 34 (44.2%) were hospitalized (median [IQR] length of stay, 1 [1-2] day). The majority of adolescents (57 [74.0%]) were treated with nonsteroidal anti-inflammatory drugs only, and 11 (14.3%) required no treatment. The highest reported incidence was observed among male adolescents aged 16 to 17 years after dose 2 (15.7 per 100 000; 95% CI, 9.7-23.9). Among those aged 16 to 17 years, the reporting rate was highest in those with a short (ie, ≤30 days) interdose interval (21.3 per 100 000; 95% CI, 11.0-37.2). Conclusions and Relevance: Results of this cohort study suggest that there was variation in the reported incidence of myocarditis or pericarditis after BNT162b2 vaccine among adolescent age groups. However, the risk of these events after vaccination remains very rare and should be considered in relation to the benefits of COVID-19 vaccination.

Epidemiology of Myocarditis and Pericarditis Following mRNA Vaccination by Vaccine Product, Schedule, and Interdose Interval Among Adolescents and Adults in Ontario, Canada.

Importance: Increased rates of myocarditis or pericarditis following receipt of COVID-19 mRNA vaccines have been observed. However, few available data are associated with differences in rates of myocarditis or pericarditis specific to vaccine products, which may have important implications for vaccination programs. Objective: To estimate rates of reported myocarditis or pericarditis following receipt of a COVID-19 mRNA vaccine by product, age, sex, dose number, and interdose interval. Design, Setting, and Participants: This population-based cohort study was conducted in Ontario, Canada (population: 14.7 million) from December 2020 to September 2021 and used data from Ontario's COVID-19 vaccine registry and passive vaccine-safety surveillance system. All individuals in Ontario, Canada, who received at least 1 dose of COVID-19 mRNA vaccine between December 14, 2020, and September 4, 2021, and had a reported episode of myocarditis or pericarditis following receipt of the COVID-19 vaccine during this period were included. We obtained information on all vaccine doses administered in the province to calculate reported rates of myocarditis or pericarditis. Exposures: Receipt of a COVID-19 mRNA vaccine (mRNA-1273 [Moderna Spikevax] or BNT162b2 [Pfizer-BioNTech Comirnaty]). Main Outcomes and Measures: All reports of myocarditis or pericarditis meeting levels 1 to 3 of the Brighton Collaboration case definitions were included. Rates and 95% CIs of reported cases of myocarditis or pericarditis per 1 000 000 mRNA vaccine doses administered were calculated by age, sex, dose number, vaccine product, and interdose interval. Results: Among 19 740 741 doses of mRNA vaccines administered, there were 297 reports of myocarditis or pericarditis meeting the inclusion criteria; 228 (76.8%) occurred in male individuals, and the median age of individuals with a reported event was 24 years (range, 12-81 years). Of the reported cases, 207 (69.7%) occurred following the second dose of the COVID-19 mRNA vaccine. When restricted to individuals who received their second dose during the period of enhanced passive surveillance (on or after June 1, 2021), the highest rate of myocarditis or pericarditis was observed in male individuals aged 18 to 24 years following mRNA-1273 as the second dose (299.5 cases per 1 000 000 doses; 95% CI, 171.2-486.4 cases per 1 000 000 doses); the rate following BNT162b2 as the second dose was 59.2 cases per 1 000 000 doses (95% CI, 19.2-138.1 cases per 1 000 000 doses). Overall rates for both vaccine products were significantly higher when the interdose interval was 30 or fewer days (BNT162b2: 52.1 cases per 1 000 000 doses [95% CI, 31.8-80.5 cases per 1 000 000 doses]; mRNA-1273: 83.9 cases per 1 000 000 doses [95% CI, 47.0-138.4 cases per 1 000 000 doses]) compared with 56 or more days (BNT162b2: 9.6 cases per 1 000 000 doses [95% CI, 6.5-13.6 cases per 1 000 000 doses]; mRNA-1273: 16.2 cases per 1 000 000 doses [95% CI, 10.2-24.6 cases per 1 000 000 doses]). Conclusions and Relevance: The findings of this population-based cohort study of Ontario adolescents and adults with myocarditis or pericarditis following mRNA COVID-19 vaccination suggest that vaccine products and interdose intervals, in addition to age and sex, may be associated with the risk of myocarditis or pericarditis after receipt of these vaccines. Vaccination program strategies, such as age-based product considerations and longer interdose intervals, may reduce the risk of myocarditis or pericarditis following receipt of mRNA vaccines.

The shifting epidemiology and serotype distribution of invasive pneumococcal disease in Ontario, Canada, 2007-2017.

BACKGROUND: Ontario, Canada introduced a publicly-funded 13-valent pneumococcal conjugate vaccine (PCV13) for infants in 2010, replacing the 10-valent (PCV10, 2009-2010) and the 7-valent (PCV7, 2005-2009) conjugate vaccine programs; a 23-valent pneumococcal polysaccharide vaccine (PPV23) has been available for older adults since 1996. We examined the epidemiology and serotype distribution of invasive pneumococcal disease (IPD) in Ontario in the context of provincial immunization programs. METHODS: We included confirmed IPD cases reported in Ontario between 2007 and 2017. We grouped serotypes according to Ontario's current immunization program (PCV13, PPV23, and non-vaccine-preventable) and calculated incidence rates (per 100,000 population) using population data. RESULTS: Between 2007 and 2017, annual incidence of IPD in Ontario ranged between 7.3 and 9.7/100,000 per year. Measures of illness severity were high throughout the period of surveillance. After PCV13 program implementation in 2010, incidence due to PCV13 serotypes decreased significantly across all age groups, with the greatest reductions in children <5 years and adults ≥65 years. Conversely, incidence due to PPV23 unique serotypes increased significantly between 2007 and 2017, with the greatest increases observed in adults 50-64 years (1.4 to 3.5/100,000) and ≥65 years (2.3 to 7.2/100,000). Similar increases were observed in incidence due to non-vaccine-preventable serotypes among all age groups, except infants <1 year. Within specific serotypes, incidence due to serotypes 3 (0.42 to 0.98/100,000) and 22F (0.31 to 0.72/100,000) increased significantly between 2007 and 2017, while incidence due to serotypes 19A and 7F decreased significantly during the PCV13 period (2010-2017). CONCLUSIONS: Eight years after PCV13 implementation in Ontario, our data suggest both direct and indirect effects on serotype-specific incidence in young children and older adults. However, overall provincial rates have remained unchanged, and IPD continues to be a severe burden on the population. The rising incidence of IPD due to PPV23 unique and non-vaccine-preventable serotypes, and the growing burden of serotypes 3 and 22F, require further study.

Canada's National Advisory Committee on Immunization (NACI): evidence-based decision-making on vaccines and immunization.

The National Advisory Committee on Immunization (NACI) provides medical, scientific, and public health advice on the use of vaccines in Canada. This article describes the structure and processes of NACI, as well as its approach to evidence-based decision-making. In a rapidly evolving and complex immunization environment, NACI has faced challenges in its endeavour to make thorough and timely evidence-based recommendations. Making population-level recommendations without formally considering the full spectrum of public health science (e.g. cost-effectiveness) presents difficulties in the implementation of NACI's recommendations. Although an improved and more transparent evidence-based NACI decision-making process is now in place, this is continuing to evolve with a current review of structures and processes underway to further improve effectiveness and efficiencies.