Proportions of laboratory confirmed influenza:
Out of 744 participants enrolled in the study, 546 (73.4%) were tested for influenza by qRT-PCR, and among them only 8 (1.5%) were positive (Table 2). Of the positive cases, one was confirmed during the 2017 influenza season and seven during the 2018 influenza season. The identified influenza subtypes were one influenza B/Yamagata during October 2017, four A/H3 during July, one A/H3 during August, and two A/H1N1pdm09 during July 2018 influenza season. Influenza virus was detected exclusively among STEMI cases. Influenza was more prevalent among recurrent AMI cases than new AMI cases during overall study period (3.6% vs. 1.2%; 0=0.16) and the 2018 influenza season (4.8% vs. 1.1%; p=0.06). Influenza positivity was higher among AMI cases with high troponin levels than those with low troponin levels during the 2018 influenza season (2.9% vs. 1.6%; p=0.62).
Proportion of CRI compared between 2017/2018 non-influenza season and all influenza seasons:
We compared the proportions of AMI cases and also sub-groups of AMI cases reporting recent CRI during the combined duration of annual influenza seasons to that during the 2017/2018 non-influenza season. Among AMI patients with high blood level of troponin, proportion of CRI was higher during influenza seasons (16.3%) compared to non-influenza season (3.1%) with p=0.07. Similarly, NSTEMI patients had a higher proportion of CRI during influenza season (14.1%) compared to non-influenza season (7.3%) with a p value of p=0.3.