Thrombosis with thrombocytopenia syndrome (TTS) following adenovirus vector COVID-19 vaccination in Canada.

INTRODUCTION: Identifying and monitoring adverse events following vaccination contributed to the safety and effectiveness of COVID-19 mass vaccination campaigns. In March 2021, international reports emerged of an adverse event following vaccination with adenovirus vector COVID-19 vaccines (ChAdOx1-S [recombinant] and Ad26.COV2.S) of thrombosis with low platelet counts, referred to as thrombosis with thrombocytopenia syndrome (TTS). We described TTS reports in Canada following adenovirus vector COVID-19 vaccines and investigated whether the observed number of events were higher than expected. METHODS: Reports of TTS following receipt of ChAdOx1-S [recombinant] or Ad26.COV2.S meeting the Canadian case definition for TTS and diagnostic certainty levels 1-3 of the Brighton Collaboration case definition, submitted to the Canadian Adverse Events Following Immunization Surveillance System and Canada Vigilance Database between February 26, 2021 and October 31, 2022 were included. Demographics and characteristics of the TTS reports are described along with an analysis comparing the observed number of reports to the expected number. RESULTS: As of October 31, 2022, 56 reports of TTS following administration of ChAdOx1-S [recombinant] and no reports following Ad26.COV2.S vaccines were reported in Canada, of which 37 had functionally positive anti-PF4 antibodies. The median age was 56 years; males accounted for 54 % of reports. Five deaths were reported. The observed number of reports exceeded the expected for all ages and sexes combined, as well as for males aged 30-49 and 60-69 years, and females aged 40-59 years. CONCLUSION: Based on international surveillance data, Canada evaluated a statistical signal of TTS following adenovirus vector vaccines. The investigation of this signal demonstrated how post-market vaccine safety surveillance systems were successful in investigating rare adverse events during the rollout of COVID-19 vaccines in Canada. As adenovirus vector vaccines continue to be administered, characterization of the association between the vaccine and TTS informs immunization programs and policies.

HIV in Canada: 2009 to 2014.

BACKGROUND: Between 1996 and 2008, the number of newly reported HIV cases in Canada fluctuated between approximately 2,100 and 2,700 cases per year. OBJECTIVE: To describe the recent trends in new diagnoses of HIV in Canada between 2009 and 2014 by age group, sex, exposure category, race/ethnicity, and region, as well as the number of perinatally HIV-exposed infants. METHODS: HIV data were compiled from two databases. The National HIV/AIDS Surveillance System is a passive surveillance system that gathers non-nominal data on a voluntary basis from all the provinces and territories of all cases that meet the national case definition, and includes data on age group, sex, race/ethnicity, country of birth, and exposure categories. The Canadian Perinatal HIV Surveillance Program is a sentinel-based surveillance system; non-nominal data is obtained through a national confidential survey completed by participating physicians. RESULTS: Since 2009 the number of new HIV cases has slowly but steadily declined from 2,391 cases in 2009 to 2,044 in 2014, which is the lowest number of annual HIV cases seen in the last two decades. The largest proportion (32%) of new HIV cases continues to be diagnosed among those 30 to 39 years of age, but the proportion of cases diagnosed among those 50 years of age or over has increased from 15% in 2009 to slightly over 20% in 2014. Approximately 75% of newly diagnosed cases are males and 25% females. In males, the most common exposure category (60%) was men who have sex with men. In females, the most common exposure category (66%) was heterosexual contact followed by injection drug use (27%). Race/ethnicity varied by sex. In males, over 50% were White, 14% were Aboriginal and 13% Black. In females, 35% were Black, 35% were Aboriginal and 22% were White. There were regional variations in HIV rates across Canada. Between 2009 and 2014, the number of perinatally HIV-exposed infants varied between 200 and 249 but the percentage of perinatal treatment increased from 87% in 2009 to 97% in 2014. CONCLUSION: The annual number of reported HIV cases in Canada has been declining in recent years. The proportion of HIV-positive mothers receiving treatment has increased and the number of confirmed HIV-infected infants has decreased.

A summary of tuberculosis drug resistance in Canada, 2003-2013.

BACKGROUND: Drug-resistant strains of tuberculosis (TB) pose a serious threat to prevention and control efforts. In response to this growing worldwide concern, the Public Health Agency of Canada (PHAC) established and maintains the Canadian Tuberculosis Laboratory Surveillance System (CTBLSS) in partnership with the Canadian Tuberculosis Laboratory Technical Network (CTLTN) and participating laboratories. OBJECTIVE: To report on national trends and patterns in anti-tuberculosis drug resistance in Canada for the years 2003 to 2013. METHOD: At the beginning of each calendar year, participating laboratories submit to PHAC reports on the results of anti-tuberculosis drug susceptibility testing for all isolates tested during the preceding year. These data are then analyzed by PHAC and the results are validated by supplying laboratories. The results are published annually as the Tuberculosis Drug Resistance in Canada series. RESULTS: In 2013, anti-tuberculosis drug susceptibility test results for 1,380 isolates were reported to PHAC. Of these, 762 (54%) were reported as Mycobacterium tuberculosis complex (MTBC) where the species was known. Two thirds (68%) of all the reported isolates originated from the three largest provinces, British Columbia, Ontario and Quebec. Overall, of the laboratory results received, 112 (8.1%) showed resistance to at least one first-line drug and, of these, the majority (93 or 83%) were monoresistant. CONCLUSION: TB drug resistance observed in Canada remains well below the global average. Over the last 10 years, the percentage of isolates with resistance to one or more of the first-line medications has decreased from 10.5% in 2003 to 8.1% in 2013.

A summary of tuberculosis in Canada, 2013.

BACKGROUND: The Public Health Agency of Canada (PHAC) monitors active TB disease through the national collaborative Canadian Tuberculosis Reporting System (CTBRS). PHAC uses TB surveillance data and reports to monitor progress towards achieving Canada's goal of preventing and controlling the transmission of TB, as outlined in Tuberculosis Prevention and Control in Canada-A Federal Framework for Action. OBJECTIVE: To provide an overview of the preliminary number of reported active (new and re-treatment) TB cases and corresponding incidence rates in Canada for 2013. METHODS: Provincial and territorial public health authorities voluntarily submit data to the CTBRS on an annual basis for all TB cases that meet the case definition for national-level surveillance. These data are analyzed by PHAC; the results of the analysis are validated by the supplying jurisdiction and are published annually as the Tuberculosis in Canada Pre-release series. RESULTS: In Canada, 1,640 new active and re-treatment TB cases were reported in 2013 for an overall incidence rate of 4.7 per 100,000 population. There was little change from preceding years in the overall distribution of cases by sex and age group. Although individuals aged 25 to 34 years old represented the largest percentage of reported cases (16%), the highest incidence rate was observed for those aged 75 years or older. Incidence rates in British Columbia, Manitoba, Saskatchewan, Nunavut, and Northwest Territories were higher than the Canadian rate, with Nunavut showing the highest incidence rate. Foreign-born individuals continue to account for the majority of reported TB cases, but the incidence rate per 100,000 population remains highest among Canadian-born Aboriginal people. CONCLUSION: Preliminary data from 2013 indicate that there were no notable changes in the number of reported cases of TB or in the overall incidence rate in Canada when compared with previous years' data. Similarly, no changes were noted in the distribution of cases by province or territory, age group or sex.

A pilot behavioural and biological surveillance survey for HIV and other bloodborne infections among Aboriginal people in Regina, Saskatchewan.

BACKGROUND: Aboriginal people in Canada are disproportionately affected by HIV and other blood-borne infections. A-Track is a national public health surveillance system designed to monitor HIV and related infections, behaviours and socio-demographic factors among Aboriginal populations in Canada. The pilot survey for the A-Track surveillance system, the first of its kind in Canada, was conducted in Regina, Saskatchewan and implemented via a community and public health partnership. OBJECTIVE: To assess the prevalence of HIV, hepatitis C, syphilis and associated risk behaviours and socio-demographic factors among Aboriginal people in Regina, Saskatchewan. This focus of the pilot survey was to provide this surveillance information for public health action and to determine whether this type of public health surveillance activity could be conducted in an urban setting across Canada. METHODS: Survey participants were self-identified Aboriginal people (First Nations, Inuit or Métis) or those who claimed Aboriginal ancestry and between the ages of 16 and 60 years. These individuals were also asked to provide a blood sample for HIV, hepatitis C and syphilis antibody testing. Descriptive analyses were performed with sex-based comparisons. RESULTS: There were 1064 people who participated in the survey. Their average age was 33 years and 51% were male. The majority of participants (93%) lived in urban Regina at the time of the survey. Just over half (53.2%) of all participants had been removed from their families during childhood; 29.9% had lived in a residential or boarding school during childhood; and 57.7% had lived at some point in a correctional facility. Among the 1,045 participants who provided a blood sample of sufficient quantity for testing, 5.2% were HIV seropositive and 55.8% of these were aware of their HIV status. The lifetime exposure to hepatitis C was 41.6%, with significantly higher proportions of males than females testing positive for hepatitis C exposure. Syphilis seroprevalence was very low (<1%). Almost three-quarters (71.5%) of participants reported being tested for HIV at least once in their lifetime and among those ever tested, 67.6% had been tested during the 12 months prior to the interview. CONCLUSION: Aboriginal people are disproportionately affected by the HIV/AIDS epidemic in Canada. The findings from the A-Track pilot survey can be used to inform and evaluate prevention and treatment services for HIV and other related infections among Aboriginal people. Lessons learned from the pilot survey could also be used to guide the possible implementation of A-Track in other urban and/or reserve locations in Canada.

Key findings from a national enhanced HIV surveillance system: 2010 - 2012.

BACKGROUND: People who inject drugs represent an important risk group in Canada's HIV epidemic. I-Track is a national public health surveillance system designed to monitor HIV and hepatitis C prevalence and associated risk behaviour factors among people who inject drugs in Canada. Information is collected through cross-sectional surveys conducted periodically at sentinel sites across Canada. I-Track Phase 3 was conducted between April 26, 2010 and August 7, 2012 across 11 participating sentinel sites. OBJECTIVE: To assess the prevalence of HIV, lifetime exposure to hepatitis C and associated risk behaviours among people who inject drugs in Canada to guide and help evaluate HIV and hepatitis C prevention, treatment and control activities. METHODS: People who had injected drugs in the six months prior to the interview and who met the minimum age of consent participated in an interviewer administered survey and provided a blood sample for HIV and hepatitis C antibody testing. Descriptive analyses were performed with sex-based comparisons. RESULTS: There were 2,687 people who participated in the survey. 68.2% were male, 60.9% were between the ages of 30 and 49 years and 36.2% self-identified as Aboriginal. Among the participants who provided a blood sample of sufficient quantity for testing, 11.2% were HIV seropositive and their lifetime exposure to hepatitis C infection was 68.0%. Drugs commonly injected included cocaine (64.3%), hydromorphone (47.2%), non-prescribed morphine (47.0%), oxycodone (37.7%) and heroin (26.7%). Injecting with previously used needles and/or other injection equipment was reported by 15.5% and 34.5% of participants, respectively. Just over one-third reported having two or more sex partners in the six months prior to the interview (34.4%) and using a condom at last sex (36.6%). The majority of participants had tested at least once in their lifetime for HIV or hepatitis C (92.9% and 91.4%, respectively). A large proportion of the participants who reported being HIV positive were under the care of a doctor (95.0%) and nearly two-thirds were taking medications prescribed for their HIV infection at the time of the interview (66.0%). CONCLUSION: HIV seroprevalence and lifetime exposure to hepatitis C infection were high among I-Track Phase 3 participants. Although many participants reported safe injection and safe sexual practices, a high proportion of participants reported risk behaviours associated with acquisition and transmission of HIV and hepatitis C. People who inject drugs continue to represent an important risk group in Canada's HIV epidemic and the I-Track Phase 3 survey findings highlight the need for continued treatment and prevention services, as well as routine and integrated testing among people who inject drugs.

Tuberculosis in Canada: 1924-2012.

BACKGROUND: Tuberculosis (TB) has been a notifiable disease since 1924 and remains an important and serious global public health challenge. Understanding the patterns and characteristics of TB are key to controlling and preventing further spread of the disease. OBJECTIVE: To provide an overview of national TB surveillance data collected through two national surveillance systems and to highlight important trends in recent years. METHODS: Trends in the incidence of TB since 1924 are presented. Descriptive results from the Canadian Tuberculosis Reporting System (CTBRS) and the Canadian Tuberculosis Laboratory Surveillance System (CTBLSS) are presented, with a focus on the years from 2002 to 2012. No statistical tests of significance were performed. RESULTS: Since the 1940s, both the number of reported TB cases and the overall Canadian incidence rate have declined. Males have always accounted for the greatest percentage of cases overall and individuals between the ages of 25 and 34 have typically accounted for the largest number of reported cases relative to other age groups. From 2002 to 2012, 66% of reported TB cases were foreign-born, but the highest burden of TB was in the Canadian-born Aboriginal population, with an average incidence rate five times that of the overall Canadian rate. Reported drug resistance in Canada remains consistently below international levels. CONCLUSION: Overall, Canada has one of the lowest TB disease rates in the world. However, foreign-born individuals and Aboriginal people continue to be disproportionately represented among cases diagnosed in Canada. Surveillance systems like the CTBRS and CTBLSS are fundamental in providing information needed to target resources where they can be most effective.