Really important new study on seroprevalence of SARS-CoV-2 among people living in precarious housing situations (including shelters) in Ile de France. A thread.  https://epicentre.msf.org/sites/default/files/2020-10/High_seroprevalence_of_SARS-CoV-2_antibodies_among_people_living_in_precarious.pdf

This is the first large study of SARS-CoV-2 antibodies in homeless & precariously housed populations. Overall 52% of 818 individuals tested were positive for antibodies. (2/)

They did methodologically sound random sampling in workers’ residences, emergency shelters & from food distribution sites. NB for U.S. folks: workers’ residences generally more crowded than shelters. They looked at 2-5 and 5+ per bedroom. Baths & kitchens shared too. (3/)

Seroprevalence was 88.7% among people living in workers’ residences, 50.5% in emergency shelters, and 27.8 % among individuals recruited from the food distribution sites. (4/)

Most (68%) who were antibody positive reported having no COVID symptoms. In multivariable analyses, level of crowding in the living arrangement was the strongest predictor of having SARS-CoV-2 antibodies. (5/)

Some key points...first, we have liked vastly underestimated the numbers of COVID-19 infections in the homeless population. (6/)

We shouldn’t declare “success” (or even good luck) when what we are observing is undercounting, particularly early in the pandemic when SARS-CoV-2 testing was so limited. This is esp true in NYC where our big COVID peak occurred prior to widespread testing availability. (7/)

We will probably never know the full extent of COVID-19 infections in NYC shelters, nor in homeless populations elsewhere in the U.S. (8/)

Second, yet again we see that crowded congregate settings are strong risk factors for spread of COVID-19. (9/)

Last, most people having been asymptomatic highlights yet again the limitations of strategies focused on symptom screening to try to prevent spread. (End)