1. Marcato AJ, Black AJ, Walker CR, Morris D, Meagher N, Price DJ, et al. Learnings from the Australian first few X household transmission project for COVID-19. Lancet Regional Health - Western Pacific. 2022;28:100573.
2. World Health Organization. The first few X cases and contacts (FFX) investigation protocol for coronavirus disease 2019 (COVID-19), version 2.2. Geneva: WHO
3. 2020 [cited 10 Jul 2022]. Available from: https://www.who.int/publications/i/item/the-first-few-x-cases-and-contacts-(-ffx)-investigation-protocol-for-coronavirus-disease-2019-(-covid-19)-version-2.2.
4. World Health Organization. Household transmission investigation protocol for 2019-novel coronavirus (COVID-19) infection. Geneva: WHO; 2020 [cited 10 Jul 2022]. Available from: https://www.who.int/publications/i/item/household-transmission-investigation-protocol-for-2019-novel-coronavirus-(2019-ncov)-infection
5. World Health Organization. Coronavirus disease (COVID-19) technical guidance: The Unity Studies: Early Investigation Protocols. Geneva: WHO; 2020 [cited 10 Jul 2022]. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/early-investigations