Review of 'COVID-19 & informal settlements: is Stay Home safe?'

Dear Authors and Editor,

This paper touches indeed on a very relevant and under-recognized topic – how do people living in poor housing conditions prevent themselves from becoming infected with Covid-19?

This paper is well written and has already undergone a couple of reviews, with a number of points already well addressed. I feel I can only make some relatively minor suggestions here.

The focus on the building, and living conditions within, is enlightening and highlights the near impossibility for people to protect themselves from Covid-19. Nevertheless, it might be helpful to look a bit broader at the community level of informal settings. A study from a refugee camp setting in Bangladesh (Truelove et.al., https://doi.org/10.1371/journal.pmed.1003144) has pointed out that the crowded living conditions would favour a rapid spread of Covid. Another study from the Moria refugee camp on Lesvos, Greece (Gilman et.al., http://dx.doi.org/10.1136/bmjgh-2020-003727) not only came to the same conclusions, but provided epidemiological modelling of a number of interventions to ‘flatten the curve’. Face masks and hygiene measures, if introduced early and with high adherence could have an impact. However, the potentially most effective measures included sectoring of the camp (with prevention of interaction between sectors, dedicating facilities such as toilets and washing facilities to sectors) and elimination and de-centralization of central convergence points (e.g. food distribution lines). This could potentially be an additional strategy in settings such as Mumbai.

Authors may explore sustainable housing designs, providing ventilation and natural light, in a bit more detail – perhaps providing some references to this. There is a number of good examples of this in South-East Asia.

Finally, authors may review the section that includes the lay media references 12 and 13, commenting on Covid-19 spread in India. Since this paper was published it became apparent that scientists and the Indian Government may have misjudged the level of herd immunity in India  (https://www.theguardian.com/world/2021/apr/29/we-are-not-special-how-triumphalism-led-india-to-covid-19-disaster).