2022 - 2023 Weekly Influenza Update: 10/02/2022 -
09/23/2023 (Week 40 -
38)
Fresno County Department
of Public Health
The 2022 - 2023 influenza season began on 10/02/2022 (week 40). This
surveillance report monitors influenza activity and is updated weekly
through the end of the 2022 - 2023 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 voluntarily reported by providers in
California.1 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. National
death and viral surveillance data is from the CDC’s FluView2
applications. California death and viral surveillance data is from the
California Weekly Report: Influenza (Flu), RSV, and Other Respiratory
Viruses.3
INFLUENZA DEATHS LOCAL, STATE AND
NATIONAL
Table 1: Cumulative Influenza Deaths for the 2022
- 2023 Influenza Season by Location and Age Range
| Fresno County4 10/02/2022-09/23/2023 |
0 |
3 |
5 |
8 |
| California3 10/02/2022-05/20/2023 |
13 |
162 |
495 |
670 |
| Nationwide2 10/02/2022-09/09/2023 |
238 |
2364 |
7095 |
9697 |
INFLUENZA TYPING AT NATIONAL, REGIONAL, STATE AND
LOCAL LEVELS
Figure 1 shows the cumulative distribution of influenza types from
national, CDC Region 9 and California from 10/02/2022 to 09/16/2023
(week 37). CDC Region 9 includes California, Arizona, Hawaii and
Nevada.2
Figure 2 shows the weekly distribution of influenza types in CDC
Region 9 from 10/02/2022 to 09/16/2023 (week 37). CDC Region 9 includes
California, Arizona, Hawaii and Nevada.2
Figure 3 shows the weekly distribution of influenza types in
California from 10/02/2022 to 05/20/2023 (week 20).3
Figure 4 shows the number of influenza positive tests by disease week
and influenza type in Fresno County from 10/02/2022 to 08/26/2023 (week
34). The number of weekly tests changes throughout the season (figure
5). The data for figure 4 comes from both public health and clinical
laboratories.5
Figure 5 shows the number of weekly influenza tests, and the
percentage of those test that are positive for influenza in Fresno
County from 10/02/2022 to 08/26/2023 (week 34). The data for figure 5
comes from both public health and clinical laboratories.5
INFLUENZA-LIKE-ILLNESS (ILI) AT EMERGENCY
DEPARMENTS
Figure 6 shows the percent of ED visits attributed to influenza-like
illness (ILI) in previous seasons and the current season as of
10/21/2023 (week 42). 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 2018
to 2023. 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. Because COVID-19 and influenza have
similar symptoms, ILI form 2019-2020 season onward may be skewed. Data
on previous seasons and current seasons is collected through
EpiCenter,6 a syndromic surveillance system.
REFERENCES/TECHNICAL NOTES
CDPH Recommendations for Influenza and Other Respiratory Virus
Testing and Reporting - 2023-2024.
CDC
FluView.
California
Weekly Report: Influenza (Flu), RSV, and Other Respiratory
Viruses.
Counts include all influenza deaths that occurred within Fresno
County among Fresno County residents.
Data from clinical sentinel and public health laboratories in the
Respiratory Laboratory Network (RLN) reporting for Fresno County. These
laboratories report the number of laboratory-confirmed influenza
positive and negative tests on a weekly basis. When possible, influenza
subtype information is also reported. For more information on the RLN,
see the California weekly influenza report (reference 3).
EpiCenter.