Monitoring COVID-19 and Influenza: The Added Value of a Severe Acute Respiratory Infection Surveillance System in Portugal
Table 5
Cross-correlation analysis between severe acute respiratory infection cases (n = 3,563), (1) COVID-19 cases (n = 2,367,770) and (2) influenza cases (n = 4,174). North and Lisbon and Tagus Valley regions, 28 September 2021–22 May 2022.
Lag
(1) COVID-19
(2) Influenza
SARI
Influenza-like illness
Cardiovascular diagnosis
Respiratory diagnosis
Respiratory infection
SARI
Influenza-like illness
Cardiovascular diagnosis
Respiratory diagnosis
Respiratory infection
−5
0.38
−0.09
0.10
−0.15
0.35
−0.08
−0.24
0.08
0.08
−0.07
−4
0.50
−0.14
0.04
−0.20
0.50
−0.18
−0.07
0.20
0.12
−0.23
−3
0.62
−0.18
0.00
−0.24
0.64
−0.22
−0.01
0.31
0.11
−0.32
−2
0.71
−0.22
0.06
−0.31
0.73
−0.20
0.08
0.43
0.07
−0.35
−1
0.80
−0.25
0.12
−0.35
0.81
−0.19
0.05
0.44
−0.08
−0.33
0
0.78
−0.38
0.07
−0.37
0.82
−0.20
0.06
0.37
−0.18
−0.31
1
0.59
−0.45
−0.04
−0.35
0.69
−0.22
0.13
0.24
−0.24
−0.28
2
0.35
−0.49
−0.13
−0.26
0.48
−0.28
0.07
0.10
−0.30
−0.28
3
0.11
−0.37
−0.15
−0.09
0.22
−0.31
0.00
0.03
−0.33
−0.27
4
−0.13
−0.20
−0.09
0.02
−0.07
−0.28
−0.02
0.02
−0.32
−0.24
5
−0.29
−0.09
0.03
0.13
−0.29
−0.25
−0.08
−0.02
−0.33
−0.19
SARI: severe acute respiratory infection; COVID-19: coronavirus disease. Values corresponding to Pearson correlations (lag = 0) are highlighted in bold.