2020 - 2021 Weekly Influenza Update: 9/27/2020 - 6/26/2021 (Week 40 - 25)
Fresno County Department of Public Health
The 2020 - 2021 influenza season began on 9/27/20 (week 40). This surveillance report monitors influenza activity and is updated weekly through the end of the 2020 - 2021 season. Providers must report laboratory-confirmed influenza-associated fatal pediatric cases in those 0-17 years old. Laboratory-confirmed influenza-associated deaths in those 18 years of age and older are voluntary reported by providers in California. Fresno County Public Health obtains the number of influenza-associated fatal cases between 0 and 17 years of age from investigations. The number of influenza-associated deaths in those 18 years and older are obtained from vital statistics records. Death and viral surveillance data for national and state regions is from the CDC’s FluView applications.
INFLUENZA DEATHS LOCAL, STATE AND NATIONAL
Fresno County: 9/27/2020 - 6/26/2021:
- Influenza-associated pediatric deaths (0-17 years old): 0
- Influenza-associated adult deaths (18-64 years old): 0
- Influenza-associated adult deaths (65 years or older): 0
California: 9/27/2020 - 6/19/2021:
- All influenza-associated deaths: 52
Nationwide: 9/27/2020 - 6/19/2021:
- Influenza-associated pediatric deaths (0-17 years old): 6
- Influenza-associated adult deaths (18-64 years old): 186
- Influenza-associated adult deaths (65 years or older): 518
INFLUENZA TYPING AT NATIONAL, REGIONAL AND STATE LEVELS
Figure 1 shows the cumulative distribution of influenza types from national, CDC Region 9 and California from 9/27/20 to 6/19/2021 (week 24). CDC Region 9 includes California, Arizona, Hawaii and Nevada.
Figure 2 shows the weekly distribution of influenza types from CDC Region 9 from 9/27/20 to 6/19/2021 (week ). CDC Region 9 includes California, Arizona, Hawaii and Nevada.
INFLUENZA-LIKE-ILLNESS (ILI) AT EMERGENCY DEPARMENTS
Figure 3 shows the percent of ED visits attributed to influenza-like illness (ILI) in previous seasons and the current season. The baseline and alert curves provide reference points to monitor ILI activity in the current season. The baseline curve and alert thresholds are estimated using prior seasons’ data from 2014 to 2019. The baseline curve is the average expected percent of ED visits due to ILI. The alert curve is the upper 95% confidence limit based off percent ED visits due to ILI. Outlier data from the 2019-2020 season caused by the COVID-19 pandemic is excluded from the baseline and alert estimations. Because COVID-19 and influenza have similar symptoms, ILI for the 2020-2021 season may be higher than expected. Data on previous seasons and current seasons is collected through EpiCenter, a syndromic surveillance system.