Excellent analysis @TheLancet
1. Governments cant minimise both deaths from COVID-19 and economic impact of viral spread
2. Spread depends on R0 (number of secondary infections by one primary case)
R0>1 spreads
COVID-19 has R0=2.5
Influenza has R0=1.5
thelancet.com/journals/lance…
1. Governments cant minimise both deaths from COVID-19 and economic impact of viral spread
2. Spread depends on R0 (number of secondary infections by one primary case)
R0>1 spreads
COVID-19 has R0=2.5
Influenza has R0=1.5
thelancet.com/journals/lance…
3. Another key factor is time from infection to when a person is infectious to others
For the 2009 influenza A H1N1 pandemic, it was around
a day to infectiousness and a few days of peak
infectiousness to others
For COVID-19, 4.5–7.5 days to infectiousness, similar to SARS
For the 2009 influenza A H1N1 pandemic, it was around
a day to infectiousness and a few days of peak
infectiousness to others
For COVID-19, 4.5–7.5 days to infectiousness, similar to SARS
4. Case fatality rate (CFR) is still unknown for COVID-19 because the true number of infected (as opposed to those tested) is unknown
Best estimates suggest a CFR for COVID-19 of about 0.3–1% which is higher than the 0.1% CFR for a moderate influenza A season
Best estimates suggest a CFR for COVID-19 of about 0.3–1% which is higher than the 0.1% CFR for a moderate influenza A season
5. Critical: It's unknown whether infectiousness starts before symptoms show
Estimates suggest considerable presymptomatic infectiousness. Danger is thus spread from asymptomatic people
In contrast, Influenza A has presymptomatic infectiousness of 1–2 days, SARS little or none
Estimates suggest considerable presymptomatic infectiousness. Danger is thus spread from asymptomatic people
In contrast, Influenza A has presymptomatic infectiousness of 1–2 days, SARS little or none
6. Key uncertainty is how many asymptomatic cases of COVID-19 there are. Estimates are 80% of people with COVID-19 have
mild or no symptoms, 14% severe disease, 6% critically ill
This implies that symptom-based control is unlikely to be sufficient
mild or no symptoms, 14% severe disease, 6% critically ill
This implies that symptom-based control is unlikely to be sufficient
7. Another uncertainty is the duration of the infectious
period for COVID-19. The infectious period is typically
short for influenza A, but it seems long for COVID-19,
perhaps lasting for 10 days or more after the incubation
period
period for COVID-19. The infectious period is typically
short for influenza A, but it seems long for COVID-19,
perhaps lasting for 10 days or more after the incubation
period
8. Implication is that COVID-19 spread will be slower than for a new
influenza A strain, and that the COVID-19 epidemic could be longer
than seasonal influenza A. This has relevance for the potential economic impact
influenza A strain, and that the COVID-19 epidemic could be longer
than seasonal influenza A. This has relevance for the potential economic impact
9. The effect of seasons on transmission of COVID-19 is unknown. But since R0 is 2–3, the warm summer months may not reduce R0 below 1 as for influenza A (with R0 = 1.1–1.5)
10. No vaccine or effective antiviral drug is likely to be
available soon. Will probably take 12-18 months
available soon. Will probably take 12-18 months
11. What's left now for mitigation is voluntary plus mandated quarantine, stopping mass gatherings, closure of educational institutes or places of work where infection has been identified, and isolation of households, towns, or cities
12. Worse case scenario with R0 around 2.5, is 60% of the population would become infected
