2021 - 2022 Weekly Influenza Update: 10/3/2021 -
06/18/2022 (Week 40 - 24)
Fresno County Department of Public
Health
The 2021 - 2022 influenza season began on 10/3/2021 (week 40). This
surveillance report monitors influenza activity and is updated weekly
through the end of the 2021 - 2022 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: 10/3/2021 - 06/18/2022:
- Influenza-associated pediatric deaths (0-17 years old): 0
- Influenza-associated adult deaths (18-64 years old): 2
- Influenza-associated adult deaths (65 years or older): 6
California: 10/3/2021 - 05/28/2022:
- All influenza-associated deaths: 56
Nationwide: 10/3/2021 - 05/28/2022:
- Influenza-associated pediatric deaths (0-17 years old): 33
- Influenza-associated adult deaths (18-64 years old): 455
- Influenza-associated adult deaths (65 years or older): 1658
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 10/3/2021 to 06/18/2022 (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 10/3/2021 to 06/18/2022 (week 24). CDC Region 9 includes
California, Arizona, Hawaii and Nevada.
Figure 3 shows the number of influenza positive tests by disease week
and influenza type in Fresno County. The number of weekly samples
changes throughout the season. The data for figure 3 comes from both
public health and private laboratories. Most data for Fresno County
comes from private laboratories where subtyping is not commonly
performed.
Figure 4 shows the percentage of samples testing positive for
influenza A or B by disease week in Fresno County. The number of weekly
samples changes throughout the season.
INFLUENZA-LIKE-ILLNESS (ILI) AT EMERGENCY
DEPARMENTS
Figure 5 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 2016 to 2021. 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 for the
2021-2022 season may be skewed. Data on previous seasons and current
seasons is collected through EpiCenter, a syndromic surveillance
system.