The two respiratory RNA viruses, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A are at the center of pandemic outbreaks. In fact, SARS-CoV-2 causes covid-19 and influenza A causes flu. Certainly, both viruses have identical hospitalization rates, intensive care admission rates and ventilators requirement. As a result, when both shows similar symptoms, testing is the only way to distinguish both.
Comparison table between SARS-CoV-2 and influenza:
| SARS-CoV-2 | Influenza A | Both |
Causes covid-19 | Causes Flu | Are RNA viruses |
Needs protein S to infect host | Needs hemagglutinin and neuraminidase to infect the host | Infect respiratory tract |
Has proofreading activity which gives lower mutation rate | Doesn’t have proofreading mechanism, so a faster mutation rate is obtained | Shows similar symptoms |
Inhibited by E1KC4 and Camostat mesylate | Inhibited by Neuraminidase inhibitors | Use surface proteins for infection |
Is eliminated by lethal mutation by EIDD-2801 due to low mutation | Treated by the 4 approved antiviral drugs | Uses viral RNA polymerase to express their proteins |
Vaccine and acquired immunity provide protection | Fast mutation rate renders the vaccine obsolete | Spread by aerosols such as during cough, sneeze or talk |
| Spreads faster than influenza | Spreads slower | Infections spread among people before even showing symptoms |
Takes longer to show symptoms (5-11 days) | Shows symptoms within 2 to 4 days | Results in complications |
Contagious for a long period (10 to 20 days) | Patients are contagious for 3-4 days and a maximum of 7 days | |
Causes more serious illness even to the healthy and secondary bacterial lung infections | Causes secondary bacterial infections but isn’t lethal to healthy individuals |
Coinfection with SARS-CoV-2 and influenza A:
Having a coinfection with both covid-19 and Influenza A shows similar clinical outcomes and symptoms to patients with covid-19 only. Hence, there’s no need to worry about having both viruses simultaneously since it has no effect on the disease outcome. In addition, influenza A infection diminishes inflammation in a certain population of covid-19 patients.
Common symptoms between covid-19 and Flu:
- Fever
- Headache
- Fatigue
- Sore throat
- Cough
- Short breath
- Runny nose
- Diarrhea
- Vomiting
- Body aches
Additional symptoms for covid-19:
- Swollen red eyes
- Taste or smell loss
- Skin rashes
References:
-Manzanares-Meza LD, Medina-Contreras O. SARS-CoV-2 and influenza: a comparative overview and treatment implications. Bol Med Hosp Infant Mex. 2020;77(5):262-273. English. doi: 10.24875/BMHIM.20000183. PMID: 33064680.
-Cheng Y, Ma J, Wang H, Wang X, Hu Z, Li H, Zhang H, Liu X. Co-infection of influenza A virus and SARS-CoV-2: A retrospective cohort study. J Med Virol. 2021 May;93(5):2947-2954. doi: 10.1002/jmv.26817. Epub 2021 Jan 27. PMID: 33475159; PMCID: PMC8013771.
-Song X, Delaney M, Shah RK, Campos JM, Wessel DL, DeBiasi RL. Comparison of Clinical Features of COVID-19 vs Seasonal Influenza A and B in US Children. JAMA Netw Open. 2020 Sep 1;3(9):e2020495. doi: 10.1001/jamanetworkopen.2020.20495. PMID: 32897374; PMCID: PMC7489826.
