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

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2.6.5 Prevention of COVID-19 infection in investigation personnel
All personnel involved in the investigation need to be trained in infection prevention and control
procedures (standard contact, droplet or airborne precautions, as determined by national or local
guidelines) (19). These procedures should include proper hand hygiene and the correct use of
surgical or respiratory face masks, if necessary, not only to minimize their own risk of infection when
in close contact with COVID-19-infected patients, but also to minimize the risk of spread among
contacts of COVID-19-infected patients.
WHO technical guidance on infection prevention and control specific to COVID-19 can be found on
the WHO website (22).
3.
Statistical analyses
3.1 Sample size
The sample size of Country X will be determined by the number of household contacts of the
confirmed COVID-19-infected individual. Every effort should be made to include all household
contacts of the confirmed COVID-19-infected individual, to maximize the statistical power of the
investigation. Larger studies will undoubtedly permit more robust analysis of potential factors
affecting the secondary infection risk, more precise estimation of the asymptomatic fraction, and
more detailed characterization of serological responses following infection.
3.2 Plan of analyses
Household transmission investigation will be not be able to answer every question we have about
COVID-19 infection, but it will contribute to respond to the key questions in the early stages of the
epidemic, which can inform public health interventions. Other protocols for investigations for
COVID-19 can assist in providing supplementary data to improve estimates of key epidemiological
parameters. All WHO protocols for COVID-19 are available on the WHO website (12).
The combination of epidemiological, virological (genomic, antigenic) and serological data can
provide unparalleled early situational awareness of the pandemic, which will promote a
proportionate and targeted public health response.
A descriptive analysis (time, place, person) of the household transmission investigation should
provide an insight into the clinical spectrum and course of disease due to COVID-19 infection
from individual cases – for example, the number of household contact with symptomatic or
asymptomatic confirmed infection, by age and underlying risk factors.
Genomic analysis of the specimens generated though this investigation can help provide a detailed
insight into the origin of the pandemic; monitor the potential spread of antiviral resistance mutation;
and identify transmission chains using the confirmed case as a potential origin (by comparing the
relatedness of two virus isolates), which in turn will help with estimation of the basic reproduction
number.
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