Another influenza season in the shadow of the COVID-19 pandemic

Article Figures & Data

TABLE 1

Distinct features of influenza and COVID-19

	Influenza	COVID-19
Seasonality	Fall-winter	Year-round

Annual incidence
Overall	8% (3% –11%)	6%–8%
Children	20% (unvaccinated)	Not applicable (no vaccine)
Adults	10% (unvaccinated)	6%–8% (unvaccinated)

Age distribution	Children > adults	Adults > children

Incubation period (days)	1 –4 days	2– 14 days

Duration of infectivity	1 day before to 7 days after onset of illness	2 days before to 10 (20 for severe cases) days after onset of illness

Onset of symptoms	More acute	More subacute

Super-spreaders (1 person infects 8 persons)	Not reported	1%

Typical or characteristic features at onset of illness	Fever, headache, dry cough	Loss of sense of taste or smell

Severity of illness
Asymptomatic	5%–50%	30%–40%
Symptomatic
Mild	98%	80%
Moderate	1%–2%	15%
Severe	0.2%	5%
Fatal	0.04%–0.1%	3%–4%

Duration of acute illness	5–7 days	2– 6 weeks

Incidence of long-term symptoms lasting longer than 4 weeks	Clinically silent viral shedding for weeks to months in immunocompromised individuals	60%–70% regardless of viral shedding

Complications	Pneumonia	Deep venous thrombosis and pulmonary embolism
Complications	Exacerbation of underlying chronic heart and lung diseases	Multisystem inflammatory disorders