Why COVID-19 is more contagious and deadly than the common flu
In short: Most viruses stay in your nose or your lungs, but SARS-CoV-2 does both. This dual-track infection strategy, combined with a unique biological 'spell-check' mechanism, allows the virus to spread rapidly while simultaneously causing severe respiratory distress. Understanding these mechanics reveals why it behaves so differently from the flu.
SARS-CoV-2 is a mutant hybrid virus composed of a small set of RNA genes enclosed in a fatty lipid sphere. Because it uses RNA instead of DNA, it is naturally prone to faster mutation. However, it possesses a unique 'spell-check' mechanism that corrects errors during replication. While most mutations are lethal to a virus, this ability allows SARS-CoV-2 to maintain its integrity while still evolving, making it harder to eliminate. The virus's structure is a spiky ball designed to recognize and stick to the ACE2 protein found on lung and kidney cells.
Its spikes are shaped to bind more strongly to ACE2 than the original SARS virus, meaning fewer viral particles are required to successfully transmit the infection. Furthermore, people with diabetes are more susceptible to severe cases because their bodies produce higher quantities of the ACE2 protein. What sets COVID-19 apart from the common cold or the flu is its 'dual-track' infection.
Most viruses infect either the upper respiratory tract (making them contagious but mild) or the lower respiratory tract (making them severe but less contagious). SARS-CoV-2 infects both. It begins in the upper tract, where people may feel few symptoms and unwittingly spread it for 5 to 14 days before it progresses to the lower tract, causing severe symptoms and triggering an intense immune response that swells lung tissue. Statistically, the difference is stark. COVID-19 has a fatality rate of 2.8% compared to 0.13% for the flu. It is estimated to be about twice as infectious as the flu, with one person affecting an average of 3 people, while the flu typically affects 1.6. Additionally, the hospitalization rate for COVID-19 is approximately 20%, significantly higher than the 1.4% seen in flu victims.
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Sources
- Summary by Intellect · source: How does Covid work? Why is Covid so deadly?
- Also: pmc.ncbi.nlm.nih.gov — COVID-19 Mechanisms in the Human Body—What We Know So Far
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