SURVEILLANCE

The purpose of this bi-weekly report is to summarize available data on confirmed outbreaks in long-term care homes (LTCHs) and retirement homes (RHs) for COVID-19, influenza and respiratory syncytial virus (RSV) in Ontario for the 2023-24 surveillance period. The 2023-24 surveillance period (henceforth referred to as 2023-24) started on August 27, 2023 (week 35, 2023) and will end on August 24, 2024 (end of week 34, 2024) This report includes data reported as of December 23, 2023. Outbreaks meeting the provincial confirmed COVID-19 1 and respiratory infection outbreak in institutions and public hospitals 2 definitions are included in this report.

COVID-19, Influenza and Respiratory Syncytial Virus Outbreaks in Long-Term Care and Retirement Homes in the 2023-24 Surveillance Period 2  The median outbreak duration of COVID-19 outbreaks in 2023-24 to date was 9 days in LTCHs and 8 days in RHs (Table 1).In comparison, the median outbreak duration of COVID-19 outbreaks in 2022-23 was 11 days in LTCHs and 9 days in RHs (Table A1).

Interpretation Notes
 The report includes data for all outbreaks in 2023-24 to date, including those that are ongoing.Therefore, outbreak trends presented in this report are subject to change as public health units (PHUs) collect and enter additional information.
 PHUs enter initial information (including aggregate count data) after declaring an outbreak and may make updates during the outbreak at their discretion.PHUs then have 14 calendar days to complete data entry for COVID-19 outbreaks after declaring them over, and 15 business days to complete data entry for influenza and RSV outbreaks after declaring them over.This means that data presented on ongoing outbreaks are not likely to be complete, and therefore should be interpreted with this in mind.

Total number of deaths 263 6 4
Median case fatality rate (IQR) 3.3% (0.0-7.1%) 0.0% (0.0-0.0%) 0.0% (0.0-0.0%) IQR: Interquartile Range; --: Refers to where data are not reported or are not presented due to low counts. Aggregate data for the 2022-23 surveillance period may be less complete.Even though PHUs were required to enter this information, more emphasis was placed on individual case data entry until April 1, 2023 when the reporting requirement was changed to allow PHUs to focus on aggregate case reporting, instead of individual linking of cases to LTCH/RH outbreaks.
 Outbreak reported week is based on the outbreak reported date, and if unavailable, the date the public health unit created the outbreak is used.
 Outbreaks without setting reported and in settings other than LTCH and RH were excluded from the analyses.For this report, PHO has not conducted manual review, validation or data cleaning of the LTCH and RH settings entered in iPHIS and CCM.
 Cases are individuals that were line listed for the outbreak (i.e., related to the outbreak) and may or may not have been confirmed by a laboratory or rapid test (i.e., line listed based on symptoms and/or epidemiologic links).These counts are reported in aggregate in CCM and iPHIS.
 Hospitalized cases are individuals who were line listed and met the outbreak case definition (i.e. for the COVID-19, influenza or RSV outbreak) who were subsequently admitted to the hospital because of their infection.These counts are reported in aggregate in CCM and iPHIS.
 Deaths are outbreak-related deaths (i.e.excluding deaths where COVID-19, influenza or RSV were unrelated to the cause of death) that occurred in individuals, who were line listed and met the case definition for those outbreaks.These counts are reported in aggregate in CCM and iPHIS.
 Attack rate was calculated as:  If the number of cases or the number of residents/staff in the affected area was not available, then the attack rate for that outbreak was not calculated and not included in the summary of attack rates.
 Attack rates calculated to be over 100% were set to 100% for the purposes of this report.
 Case hospitalization rate was calculated as:  If the number of hospitalizations was missing then the hospitalization rate was not calculated and not included in the summary of hospitalization rates.
 Hospitalization rates calculated to be over 100% were set to 100% for the purposes of this report.
 Case fatality rate was calculated as:  If the number of deaths was missing then the case fatality rate was not calculated and not included in the summary of case fatality rates.
 Case fatality rates calculated to be over 100% were set to 100% for the purposes of this report.
 Duration was calculated as: Date of onset of illness in last case -Date onset of illness in first case.It is not calculated for outbreaks missing either of these dates.
 If an outbreak had a calculated duration less than 0 days, then the outbreak was excluded from calculations of summary duration measures.
 Duration is not calculated for ongoing outbreaks.
 The interquartile range (IQR) is between the 25 th and 75 th percentiles of the data.
 Further data caveats and methods are available in the technical notes for the Ontario Respiratory Virus Tool.For Further information For more information, email Healthprotection@oahpp.ca.

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Table 2b : Confirmed outbreaks in LTCHs among staff, by pathogen, Ontario: August 27, 2023 -December 23, 2023
IQR:Interquartile Range; --: Refers to where data are not reported or are not presented due to low counts.

Table 3a : Confirmed outbreaks in RHs among residents, by pathogen, Ontario: August 27, 2023 -December 23, 2023
IQR:Interquartile Range; --: Refers to where data are not reported or are not presented due to low counts.

Table 3b : Confirmed outbreaks in RHs among staff, by pathogen, Ontario: August 27, 2023 -December 23, 2023
For the 2023-24 surveillance period data for COVID-19 outbreaks, including aggregate case counts, were based on information successfully extracted from CCM by Public Health Ontario (PHO) as of December 27, 2023 at 1 p.m.For the 2022-23 surveillance period, data were based on information successfully extracted from CCM by PHO as of October 3, 2023 at 1 p.m. For the 2023-24 surveillance period data for influenza and RSV outbreaks, including aggregate case counts, were based on information successfully extracted from iPHIS by PHO as of December 28, 2023 at 9 a.m.For the 2022-23 surveillance period data were based on information successfully extracted from iPHIS by PHO as of November 15, 2023 at 9 a.m. Outbreaks not meeting the provincial definition for respiratory infection outbreaks in institutions and public hospitals (e.g., 0 aggregate cases reported) were excluded from the analyses.Onlyoutbreaks reported on or after August 28, 2022 to the Saturday immediately before the extraction dates are included in the report.iPHIS and CCM are dynamic disease reporting systems that allow ongoing updates to data previously entered.As a result, data extracted from CCM and iPHIS represent a snapshot at the time of extraction and may differ from previous or subsequent reports.
IQR:Interquartile Range; --: Refers to where data are not reported or are not presented due to low counts.COVID-19, Influenza and Respiratory Syncytial Virus Outbreaks in Long-Term Care and Retirement Homes in the 2023-24 Surveillance Period 6 Technical Notes   Observed trends over time should be interpreted with caution for the most recent period due to reporting and/or data entry lags.Unless otherwise noted, previously reported data may change, unless otherwise noted, as PHUs update and close outbreaks. All data in this report relating to cases, hospitalizations and deaths are based on aggregate counts reported in CCM and iPHIS.Aggregate counts can include cases that are symptomatic or that test positive by rapid antigen test (RAT).In contrast, previously reported counts of COVID-19 cases, hospitalizations and deaths in LTCHs and RHs were based on individual reports of PCRconfirmed cases, which were identified in CCM by risk factor and/or outbreak linkage.As a result, aggregately reported data in this report should not be compared directly to outbreak indicators that are based on individually reported cases.

Table A3b : Confirmed outbreaks in RHs among staff, by pathogen, Ontario: August 28, 2022 -August 26, 2023 Measure COVID-19 Influenza RSV Total number of cases among staff 2,768 81 39
Interquartile Range; --: Refers to where data are not reported Citation Ontario Agency for Health Protection and Promotion (Public Health Ontario).COVID-19, influenza and respiratory syncytial virus outbreaks in long-term care homes and retirement homes in the 2023-24 surveillance period.Toronto, ON: King's Printer for Ontario; 2023.DisclaimerThis document was developed by Public Health Ontario (PHO).PHO provides scientific and technical advice to Ontario's government, public health organizations and health care providers.PHO's work is guided by the current best available evidence at the time of publication.The application and use of this document is the responsibility of the user.PHO assumes no liability resulting from any such application or use.This document may be reproduced without permission for non-commercial purposes only and provided that appropriate credit is given to PHO.No changes and/or modifications may be made to this document without express written permission from PHO. IQR: