Relationship between enteric pathogens and acute gastroenteritis disease severity: a prospective cohort study.

OBJECTIVES: To evaluate the relationship between individual bacterial and viral pathogens and disease severity. METHODS: Children <18 years with three or more episodes of vomiting and/or diarrhoea were enrolled in two Canadian paediatric emergency departments between December 2014 and August 2016. Specimens were analysed employing molecular panels, and outcome data were collected 14 days after enrolment. The primary outcome was severe disease over the entire illness (symptom onset until 14-day follow-up), quantified employing the Modified Vesikari Scale (MVS) score. The score was additionally analysed in two other time periods: index (symptom onset until enrolment) and follow-up (enrolment until 14-day follow-up). RESULTS: Median participant age was 20.7 (IQR: 11.3, 44.2) months; 47.4% (518/1093) and 73.4% (802/1093) of participants had index and total MVS scores ≥11, respectively. The most commonly identified pathogens were rotavirus (289/1093; 26.4%) and norovirus (258/1093; 23.6%). In multivariable analysis, severe disease over the entire illness was associated with rotavirus (OR = 9.60; 95%CI: 5.69, 16.19), Salmonella (OR = 6.61; 95%CI: 1.50, 29.17), adenovirus (OR = 2.53; 95%CI: 1.62, 3.97), and norovirus (OR = 1.43; 95%CI: 1.01, 2.01). Pathogens associated with severe disease at the index visit were: rotavirus only (OR = 6.13; 95%CI: 4.29, 8.75), Salmonella (OR = 4.59; 95%CI: 1.71, 12.29), adenovirus only (OR = 2.06; 95%CI: 1.41, 3.00), rotavirus plus adenovirus (OR = 3.15; 95%CI: 1.35, 7.37), and norovirus (OR = 0.68; 95%CI: 0.49, 0.94). During the follow-up period, rotavirus (OR = 2.21; 95%CI: 1.50, 3.25) and adenovirus (OR = 2.10; 95%CI: 1.39, 3.18) were associated with severe disease. CONCLUSIONS: In children presenting for emergency department care with acute gastroenteritis, pathogens identified were predominantly viruses, and several of which were associated with severe disease. Salmonella was the sole bacterium independently associated with severe disease.

Successful methodology for large-scale surveillance of severe events following influenza vaccination in Canada, 2011 and 2012.

In 2011 and 2012, a nationwide Canadian vaccine safety surveillance network rapidly collected safety data from healthcare workers (HCW) during the first weeks of the annual influenza vaccination campaign. This network provided the first available post-marketing safety data on seasonal influenza vaccines with information on background rates as a comparator. In 2012, these data were used to investigate a possible safety concern regarding a particular vaccine. An online questionnaire was provided to participating HCW two weeks before the annual influenza vaccination campaign for controls, and eight days after influenza vaccination for vaccinees. Control and vaccinees were requested to report health events occurring in the seven days prior to receiving the questionnaire. Control data were used to calculate background rates. HCW reporting a severe event were followed-up by telephone within 48 hours of the online report to validate the report and check on their health status. More than 22,000 vaccinated HCW were enrolled and surveyed over two seasons and > 90% reported no severe event following vaccination. Validated severe event rates were similar in vaccinated HCW and unvaccinated HCW (2.2% vs 2.3%; p < 0.70). The questionnaire was accurately completed for most reported symptoms, matched the validated report and was able to detect events of interest. Prior to the safety concern, the implicated vaccine was in use at one centre. Reassuring safety data were provided to public health authorities 48 hours after the vaccine was temporarily suspended. Data from this and similar networks can be used for rapid evaluation of vaccine safety and for safety assessment as required by the European Medicines Agency in 2015.