Covid vs flu symptoms
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Comparing COVID-19 and Flu Symptoms
Common Symptoms of COVID-19 and Influenza
Fever and Cough: Predominant Symptoms
Both COVID-19 and influenza commonly present with fever and cough. In COVID-19, fever is reported in approximately 74% of cases, while influenza shows a slightly lower incidence of fever at 68%1. Cough is also a prevalent symptom in both diseases, with COVID-19 patients reporting it in 70% of cases and influenza patients in 93%1 2.
Muscle Pain and Headache: More Common in Influenza
Muscle pain and headache are more frequently observed in influenza patients compared to those with COVID-19. Influenza patients report muscle pain in 94% of cases and headache in 91%, whereas these symptoms are less common in COVID-19, with muscle pain in 29% and headache in 21% of cases1 2.
Sore Throat and Rhinorrhea: Less Frequent in COVID-19
Sore throat and rhinorrhea (runny nose) are significantly less common in COVID-19 patients. Sore throat is reported in only 12% of COVID-19 cases compared to 49% in influenza type A and 38% in influenza type B1 2. Similarly, rhinorrhea is observed in just 4% of COVID-19 cases, while it is much more common in influenza, appearing in 44.5% of type A and 49% of type B cases2.
Distinguishing Features
Radiographic Findings
COVID-19 patients often exhibit abnormal chest radiology, with 84% showing such signs, compared to 57% in influenza type A and 33% in type B2. This significant difference in radiographic findings can aid in distinguishing between the two diseases.
Incubation Period and Hospitalization Duration
The incubation period for COVID-19 is longer, averaging 6.4 days, compared to 3.4 days for influenza type A2. Additionally, COVID-19 patients tend to have longer hospital stays, averaging 14 days, compared to 6.5 days for influenza type A and 6.7 days for type B2.
Severity and Complications
COVID-19 can lead to more severe complications, such as acute respiratory distress syndrome (ARDS) and higher case fatality rates among hospitalized patients (6.5%) compared to influenza type A (6%) and type B (3%)2 4. However, in children, COVID-19 generally presents a milder course than influenza, with fewer complications and a limited inflammatory response3.
Coinfections and Long-term Effects
Coinfections with Influenza
Coinfections of COVID-19 and influenza are rare but can occur. Patients with both infections typically present with symptoms like fever, cough, and shortness of breath, similar to those with only COVID-194 7. However, symptoms such as nasal congestion and sore throat may be more pronounced in coinfected patients4.
Long COVID vs. Long Flu
Long COVID, characterized by persistent symptoms such as fatigue, dyspnea, and neurocognitive issues, affects a significant proportion of COVID-19 patients, with about 30% of hospitalized patients developing long-term symptoms5 9. In comparison, long-term symptoms following influenza, termed "long Flu," are also observed but with notable differences in symptomatology and healthcare utilization5.
Conclusion
While COVID-19 and influenza share several common symptoms, key differences in symptom frequency, radiographic findings, incubation periods, and severity can help distinguish between the two. Understanding these differences is crucial for timely and accurate diagnosis, which is essential for effective patient management and containment of outbreaks.
Sources and full results
Most relevant research papers on this topic
Comparison of the clinical differences between COVID-19, SARS, influenza, and the common cold: A systematic literature review.
A greater number of general symptoms should lead to a diagnosis of influenza or common cold rather than COVID-19.
Systematic ReviewComparison of influenza type A and B with COVID‐19: A global systematic review and meta‐analysis on clinical, laboratory and radiographic findings
COVID-19 and influenza have many differences in clinical manifestations and radiographic findings, making timely detection and distinction crucial for effective treatment.
Meta-Analysis
Rigorous Journal
Highly CitedComparison of the Clinical and Laboratory Features of COVID and Influenza in Children
COVID-19 and Influenza in children share common symptoms, but laboratory tests show limited inflammatory response in COVID-19, potentially explaining fewer complications and a milder clinical course.
Systematic ReviewThe clinical characteristics of pneumonia patients coinfected with 2019 novel coronavirus and influenza virus in Wuhan, China
Patients with both COVID-19 and influenza virus infection showed similar clinical characteristics, but nasal tampon and pharyngalgia symptoms may be more prone to appear in coinfection patients.
Observational StudyHighly CitedPrevalence and characteristics of long COVID in elderly patients: An observational cohort study of over 2 million adults in the US
Long COVID is more prevalent in elderly patients and has higher incidence of symptoms and healthcare utilization compared to long Flu.
Observational StudyModeling the Onset of Symptoms of COVID-19
The order of symptoms in COVID-19 patients differs from other respiratory diseases, suggesting fever should be used to screen for entry into facilities and record symptom occurrence.
Observational StudyHighly CitedAre coinfections with COVID‐19 and influenza low or underreported? An observational study examining current published literature including three new unpublished cases
COVID-19/influenza coinfection is rare, but similar clinical presentation and laboratory findings suggest that COVID-19 control measures may help limit the spread of these respiratory pathogens.
Systematic ReviewCOVID‐19 diagnosis and management: a comprehensive review
Quarantine is the only effective intervention for decreasing COVID-19 contagion, while antiviral drugs, chloroquine, and respiratory therapy are used for treatment.
Systematic ReviewHighly CitedSymptoms and signs of long COVID: A rapid review and meta-analysis
Long COVID symptoms include fatigue, dyspnea, olfactory dysfunction, myalgia, cough, and gustatory dysfunction, with high heterogeneity in meta-analysis affecting pooled incidence estimates.
Meta-AnalysisRigorous JournalSmell dysfunction: a biomarker for COVID‐19
Smell dysfunction may serve as a biomarker for COVID-19, as it has been associated with patient-reported symptoms but no empirical olfactory testing has been performed.
Highly Cited