Background Research on SARS-CoV-2 transmission within households and other close settings using serological testing is scarce. Methods We invited COVID-19 cases diagnosed between February 27 and April 1, 2020, in canton of Vaud, Switzerland, to participate, along with household members and other close contacts. Anti-SARS-CoV-2 IgG antibodies were measured using a Luminex immunoassay. We estimated factors associated with serological status using generalized estimating equations. Results Overall, 219 cases, 302 household members, and 69 other close contacts participated between May 4 and June 27, 2020. More than half of household members (57.2%, 95%CI 49.7-64.3) had developed a serologic response to SARS-CoV-2, while 19.0% (95%CI 10.0-33.2) of other close contacts were seropositive. After adjusting for individual and household characteristics, infection risk was higher in household members aged 65 or more than in younger adults (aOR 3.63, 95%CI 1.05-12.60), and in those not strictly adhering to simple hygiene rules like hand washing (aOR 1.80, 95%CI 1.02-3.17). The risk was lower when more than 5 people outside home were met during semi-confinement, compared to none (aOR 0.35, 95%CI 0.16-0.74). Individual risk of household members to be seropositive was lower in large households (22% less per each additional person). Conclusions During semi-confinement, household members of a COVID-19 case were at very high risk of getting infected, 3 times more than close contacts outside home. This highlights the need to provide clear messages on protective measures applicable at home. For elderly couples, who were especially at risk, providing external support for daily basic activities is essential.

Among women delivering in a public hospital, tobacco and alcohol consumption during pregnancy was important and significantly influenced by the habits and attitude of close relatives. The involvement of relatives in health promotion interventions should be addressed.

Health professionals are increasingly urged to act to protect individuals and populations against the negative effects of climate and environment change on health. However, the amount of evidence supporting initiatives to that end is unknown. We explored the literature examining the awareness, preparedness, and role of healthcare professionals to inform about the impact of climate change on health on the one hand, and literature about the effectiveness of interventions mediated by health professionals aiming at reducing the environmental impact of human activities on the other hand. We included 137 articles published between 2000 and 2020, mostly in general medical and nursing journals. The typical article was a perspective, commentary, or other special article aimed at alerting readers about the impact of climate and environment change on health. We identified 22 studies, of which only two reported interventions. Despite increasing efforts of health professionals to address climate and environment change and related health risks, health literature supporting such efforts remains scarce, and studies assessing the effectiveness of interventions are lacking. We need appropriate evidence to indicate which interventions should be prioritized, considering that the association of health issues with climate and environment change could constitute an effective lever for change.