Table 1.
Comparison of seasonal influenza and COVID-19, USA, 2019–2020
| Variable | Influenza | COVID-19 |
|---|---|---|
| Virus type | Enveloped single-stranded RNA virus (negative sense) | Enveloped single-stranded RNA virus (positive sense) |
| Cell receptor | N‑acetyl neuraminic acid | Angiotensin-converting enzyme 2; possibly also host cellular serine protease |
| Seasonal | Yes | Unknown |
| Precautions | Droplet a | Airborne plus gowns, gloves, and eye protection |
| Duration of infectiousness | From 1 day before illness to as long as severe symptoms persist; virus has been detected up to 21 days after onset of illness | Possibly from 3 days before onset of symptoms in some cases until clearance of the virus |
| Treatment options | Yes (multiple FDA-approved drugs) | No established therapies |
| Vaccine | Yes | No |
| Incubation time: Exposure to onset of symptoms | 1–4 days, median 2 days | 2–14 days |
| Pregnant patients at high risk for severe illness | Yes | ?No |
| Children at risk for severe illness | Yes | ?No |
| Number of cases USA | 39–56 million cases (10/1/19–4/4/20) | 740,557 (4/19/20)b |
| Number of deaths USA | 24,000–62,000 (10/1/19–4/4/20) (up to 0.16% of cases) | 38,979 (4/19/20) (5.3% of cases)b |
a Aerosol transmission may be possible but is controversial and may be dependent on the strain of influenza virus [5, 7]
b The number of cases listed is likely to be a serious underestimate of the total number of infections given the infrequency of testing persons not admitted to a hospital in the USA. Therefore, the percentage of deaths listed is likely to greatly overestimate the actual percentage