It is unclear if – after symptom onset of a primary case of coronavirus disease-2019 (COVID-19) in a household – ensuing chains of transmissions among household members occur and if household epidemiology of COVID-19 is modified by the different circulating variants. We analysed data of 52 774 household clusters to investigate the day of symptom onset of ensuing cases in households relative to the symptom onset of the primary case within the household. Irrespective of cluster size or age of the primary case, 95% of all secondary household cases had symptom onset within 14 days after the symptom onset of the primary case. Stratification by variant showed that the mean interval from symptom onset of the primary case to the symptom onset of secondary cases decreased significantly from 4.8 days (wildtype) to 4.5 days (alpha) and 4.0 days (delta). Similarly, the cumulative proportion of 95% of secondary cases occurred within 14 days (wild type), 12 days (alpha) and 10 days (delta). Our findings suggest that during dominant delta circulation – apart from rare individual constellations – a 10-day household quarantine after symptom onset of the primary case is sufficient for household contacts who remain COVID-free.

It is excellent to be able to present this latest achievement in the onward march of remote mapping, the art and science of exploring archaeological sites without digging them. Using a particularly graphic case study in Hungary, the author shows that deposits characterised by geophysical and chemical means can reveal their plans and the emphasis of their activity in some detail. This is not only a rapid and economic means of landscape investigation, but offers striking research results over a broad canvas, indicative of the numerous small dispersed settlements that so often escape the attention of the great excavation campaigns.