3.1 Comparison between H1N1 infected patients and SAR-COV-2
infected patients.
Demographic characteristics, ABO blood group and comorbidities prior to
admission of all hospitalized patients are presented in Table 1. The
proportions of men and patient blood group were similar in the two
groups. The median ages of H1N1 and
SAR-COV-2-infected patients were
50.0 years (IQR 30.0-65.0, range 20.0-90.0) and 47.0 years (IQR
33.0-61.0, range 18.0-90.0), respectively (P > .05). The
duration from disease onset to admission was longer in H1N1 patients
(4.0 vs 3.0, p = 0.001). As for comorbid conditions at admission,
cerebrovascular disease, diabetes mellitus, hyperlipidemia and COPD were
more common in H1N1-infected populations than those in
SAR-COV-2-infected group. There were no significant differences between
the groups in proportion of ABO blood group. Clinical symptoms were more
frequently shown in H1N1-infected group than
SAR-COV-2-infected group at
admission except for dry cough and diarrhea. Diarrhea was more common in
SAR-COV-2-infected group: (4.02% vs 0.91%, P = .033). The difference
in the proportion of fever was the most obvious: (82.73% vs 48.59%, p
< .001). In addition, H1N1 patients had higher admission
temperature (median 37.8 °C, IQR (36.8-38.2) vs. 37.2 (36.8-37.6); p
< .001). The comparison of the results of routine blood tests
at admission are shown in table 1. For infection-related biomarkers,
C-reactive protein level and procalcitonin level on admission were
higher in H1N1 patients (median C-reactive protein level 44.96 mg/L, IQR
20.36-77.75; median procalcitonin
level 0.16 ng/mL [0.05-0.61]) than non-ICU patients (median
C-reactive protein level 32.08 mg/L [12.08-36.30], p
<.001; median procalcitonin level 0.07 ng/mL [0.04-24.7],
p= 0.0332).
As for treatment and clinical outcome on the two viruses,
SAR-COV-2-infected patients were
significantly more frequently received antiviral therapy (84.74% vs
76.82%, p = .029) (table 2), as was oxygen therapy: (62.65% vs 40.91,
p < 0.001). Pneumonia and multilobar infiltrates were more
frequent occurred in SAR-COV-2-infected patients. SAR-COV-2-infected
patients’ median duration of hospital stay was longer than those of H1N1
infected patients: (17.5 days vs 7 days, P < .001). Generally,
the rates of adverse clinical events were higher in elder patients
(Figure 1). In univariable analysis, the odds of hospitalization
outcomes (length of stay in hospital >20 days and
pneumonia) in SAR-COV-2-infected patients were higher than in those
hospitalized with H1N1 infection, albeit with a lower risk for highest
temperature > 39°C during hospitalization. When adjusting
for age, sex, comorbidities and smoking history our regression model
showed similar results (Figure 2).
3.2 Comparison betweenSAR-COV-2 infected
patients andmixed-infected patients.
When comparing SAR-COV-2 infected patients with mixed-infected patients
(Table 1), we observed that mixed-infected patients (n=36) tended to be
older (median 56.0 years vs 47.0 years, p=0.027), with a higher
proportion of patients with more than two comorbidities (25.0% vs
8.84%, P = .004). There were no major differences regarding sex or
blood group. Myalgia was more frequent in mixed-infected patients; other
symptoms showed no significant difference between the two groups. For
comparison of the results of routine blood tests, neutrophil count and
C-reactive protein level were significantly higher in mixed-infected
patients (median neutrophil count 3.67×109 cells/L; median C-reactive
protein level 51.2 mg/L) than patients infected with SAR-COV-2 alone
(median neutrophil count 2.83×109 cells/L, P = 0.0081; median C-reactive
protein level 32.08 mg/L, P < 0.001) whilst haemoglobin and
albumin were in a lower level.
Significantly more mixed-infected patients underwent vasoactive agents
therapy and ventilation (table2). The length of hospital stay was longer
(20.0 vs 17.5 days, P = 0.02) and the rate of secondary bacterial
infections (13.89% vs 3.21%, P = 0.004), admittance to ICU (19.44% vs
5.22%, P = 0.002) and mortality (2.78% vs 0, P = 0.008) were
significantly higher in mixed-infected patients.