Household transmission of the Delta COVID-19 variant in Queensland, Australia: a case series

Abstract

Household transmission plays a key role in the spread of Covid-19 through populations.In this paper, we report on the transmission of Covid-19 within households in a metropolitan area in Australia, examine the impact of various factors and highlight priority areas for future public health responses. We collected and reviewed retrospective case report data and follow-up interview responses from households with a positive case of the Delta Covid-19 variant in Queensland in 2021. The overall secondary attack rate (SAR) among household contacts was 29.6% and the mean incubation period for secondary cases was 4.3 days. SAR was higher where the index case was male (57.9% vs. 14.3%) or aged ≤12 years (38.7% vs. 17.4%) but similar for adult contacts that were double vaccinated (35.7%) and unvaccinated (33.3%). Most interview participants emphasized the importance of clear, consistent and compassionate health advice as a key priority for managing outbreaks in the home. The overall rate of household transmission was slightly higher than that reported in previous studies on the wild Covid-19 variant and secondary infections developed more rapidly.While vaccination did not appear to affect the risk of transmission to adult subjects, uptake in the sample was ultimately high.

Does COVID-19 Vaccination Protect Contact Persons? A Systematic Review

“…This assumption is supported by the finding that those who encouraged their families and friends to get vaccinated are more likely to accept a COVID-19 vaccination [82]. The presence of symptoms may also be relevant for a secondary transmission from index cases, as symptomatic infections have been described to increase transmissibility from the index cases [83]. Finally, the behavior may be different between households of vaccinated and unvaccinated index cases.…”

COVID-19 isolation/quarantine rules in home care patients

“…Previous studies reported a poor adherence to self-isolation rules and the need for a better information about isolation/quarantine protocols from public health officials [7]. Home health care workers care for played an important role in supporting patients with confirmed and suspected COVID-19 who remain at home [8,9].…”