Early Investigations Protocols

- May 08, 2020-

The emergence of a new virus means that understanding transmission patterns, severity, clinical features and risk factors for infection will be limited at the start of an outbreak. To address these unknowns, WHO has provided Four Early Investigation Protocols (rebranded the WHO Unity Studies).

These protocols are designed to rapidly and systematically collect and share data in a format that facilitates aggregation, tabulation and analysis across different settings globally. One additional study to evaluate environmental contamination of COVID-19 is also provided.

Data collected using these investigation protocols will be critical to refine recommendations for case definitions and surveillance, characterize key epidemiological features of COVID-19, help understand spread, severity, spectrum of disease, and impact on the community and to inform guidance for application of countermeasures such as case isolation and contact tracing.  

The Unity Studies: WHO Early Investigations Protocols


Why Unity Studies?Study focusObjectives
The First Few COVID-19 X cases and contacts transmission investigation protocol (FFX)Cases and close contacts in the general population or can be restricted to close settings (like households, health care settings, schools).The primary objectives of this FFX investigation among cases and close contacts are to providedescriptions or estimates of the:
  • clinical presentation of COVID-19 infection and course of associated disease;

  • secondary infection rate (SIR) and secondary clinical attack rate of COVID-19 infection among close contacts (overall, and by key factors such as setting, age and sex, for various end-points);

  • serial interval of COVID-19 infection;

  • symptomatic proportion of COVID-19 cases (through contact tracing and laboratory testing); and identification of possible routes of transmission.

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Household transmission of COVID-19 investigation protocol (HH)Cases and close contacts in household setting
  • To better understand the extent of transmission within a household by estimating the secondary infection rate for household contacts at an individual level, and factors associated with any variation in the secondary infection risk.

  • To characterize secondary cases including the range of clinical presentation, risk factors for infection, and the extent and fraction of asymptomatic infections.

  • To characterize serologic response following confirmed 2019-nCoV infection

Assessment of COVID-19 risk factors among Health workers (HW) protocolFor health workers in a health-care setting in which a confirmed case has received care
  • To better understand the extent of human-to-human transmission among health care workers, by estimating the secondary infection rate1 for health care worker contacts at an individual level. 

  • To characterize the range of clinical presentation of infection and the risk factors for infection among health care workers. 

  • To evaluate effectiveness of infection prevention and control measures among health care workers

Population-based age-stratified seroepidemiological investigation protocol for COVID-19 Virus infection in the general population 
  • To estimate age-specific seroprevalence 

Surface sampling of COVID-19 virus: A practical “how to” protocol for health care and public health professionalsFor environmental surfaces 
  • To assess the extent and persistence of surface contamination with COVID-19 

  • To identify environmental surfaces which may play a role in onwards transmission of COVID-19