Coronavirus disease (COVID-19) technical guidance by WHO Household transmission investigation protocol | Page 20

More advanced analysis, using the investigation forms/questionnaires and specimens generated,
should allow robust estimation of key epidemiological parameters as described in Table 2. The table
includes a comments/limitations section, which provides insight into the strengths and weaknesses
of this protocol.
Table 2. Definition and sources of epidemiological parameters that can be estimated during a
household transmission investigation.
Parameter
Course of disease
(time, person and
place).
Health-care-seeking
behaviours.
Symptomatic
proportion of cases or
asymptomatic
fraction.
Hospitalization rate or
incident
hospitalizations.
Definition
(“simplified” expression of
the definition)
A description of the
distribution of cases by time,
person and place.
Determination of the
proportion of people who
sought health care (not
necessarily just
hospitalization).
The proportion of cases who
show symptoms or signs of
COVID-19 infection
or
The proportion of cases who
do not show symptoms or
signs of COVID-19 infection.
A measure of the frequency
of hospitalized cases of
COVID-19 among the
confirmed cases in the
household in a defined
period of time.
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Form and questions
where data can be
obtained to
calculate the
parameters
concerned
Demography
Date of laboratory
confirmation
Location
Comments, limitations
• Location will need to be
supplemented by
notification data to
indicate geospatial
trends.
Form 1A: Q3, Q4,
Q5
Form 1B: Q4, Q5
Form 2, 3, 4, 5
Form 1A: Q6
Laboratory
confirmation and
symptoms.
Form 1A: Q6
Form 1B: Q6
Form 2, 3, 4, 5
Symptom diary
Hospitalization data.
Form 1A: Q6
Form 1B: Q7
Form 2,3,4
• The numerators of
interest are the numbers
of those household
contacts reporting
various signs and
symptoms of infection
(e.g. fever, cough) and
the number/proportion
of those contacts
reporting no signs or
symptoms (i.e. the
asymptomatic fraction);
the denominator is the
total number of cases.