Coronavirus disease (COVID-19) technical guidance by WHO Household transmission investigation protocol | Page 41

Appendix B: Comparison between the features and complementarity of the main coronavirus disease 2019 (COVID-19) early
investigation protocols
The First Few X cases and contacts (FFX)
investigation protocol for coronavirus
disease 2019 (COVID-19)
Household transmission investigation
protocol for coronavirus disease 2019
(COVID-19) Protocol for assessment of potential risk factors
for coronavirus disease 2019 (COVID-19) among
health workers in a health-care setting
Population The First Few X number of confirmed
cases of COVID-19 and their close
contacts in the general population. Household close contacts of confirmed
cases of COVID-19 (smaller
epidemiological unit than FFX). Health workers in a health-care setting in which a
confirmed COVID-19 case has received care.
Aim Transmission dynamics, severity and
clinical spectrum, in a proxy of the
general population.
Transmission dynamics, severity and
clinical spectrum, through estimates of,
primarily:
 the clinical presentation of COVID-19
infection and course of associated
disease.
 the secondary infection rate (SIR)
and secondary clinical attack rate of
COVID-19 among close contacts.
 the serial interval of COVID-19
infection.
 the symptomatic proportion of
COVID cases (through contact
tracing and laboratory testing).
 identification of possible routes of
transmission Transmission dynamics, severity and
clinical spectrum, in household settings. Transmission dynamics, severity and clinical
spectrum, in closed settings such as hospitals and
health-care centres.
Key epidemiological data to
complement and reinforce the findings
of FFX, in the areas of, primarily:
 the proportion of asymptomatic
cases and symptomatic cases.
 the incubation period of COVID-19
and the duration of infectiousness
and of detectable shedding.
 the serial interval of COVID-19
infection.
 the reproduction numbers: R 0 and R
of COVID-19.
 clinical risk factors for COVID-19,
and the clinical course and severity
of disease. Transmission dynamics in health-care settings,
through estimates of:
 she secondary Infection rate (SIR) among
health workers.
 the range of clinical presentation and risk
factors for infection.
 the serological response following
symptomatic COVID-19 infection
 possible routes of transmission.
Potential
output and
analysis.
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