Research in action: Voluntary Isolation Centres: Crucial to Reducing Household Transmission of COVID-19

During the pandemic, households were a frequent site of COVID-19 transmission. Early on, studies found that up to 17% of people living with an infected family member also got the virus. As more contagious variants appeared, this number rose to 31% between mid-2020 and early 2021, despite public health recommendations to self-isolate, test, and wear mask. Many people, particularly in crowded or multi-generational homes, struggled to isolate effectively, particularly before vaccines became widely available. To help with this issue, many places around the world, including Canada, established voluntary isolation centers. These centers offered a supported environment for individuals who tested positive for COVID-19 but were not able to isolate at home, helping to reduce household spread. In September 2020, Toronto Public Health opened the Toronto Voluntary Isolation Centre (TVIC).

A new study co-authored by Public Health Ontario (PHO) researchers, Drs. Kevin Brown, Kevin Schwartz, and Nick Daneman, as well as Ana Cecilia Ulloa, Sarah A. Buchan, and Rachel Laxer, aimed to understand how well isolation centers reduce the spread of COVID-19 in households. Here’s a more detailed look at the findings and public health implications.

Why is this study important?
This study addresses the gap in available evidence on the effectiveness of isolation facilities and support services, in preventing the spread of COVID-19. Before vaccines were widely available in 2021, there weren’t many proven ways to stop the virus from spreading in homes, aside from testing, self-isolation, and wearing masks. The paper provides evidence to support public health leaders in using a voluntary isolation centre model to reduce the spread of COVID-19 within household. In the context of a future pandemic, making sure they are available to everyone who needs them could have a big impact on controlling the spread of disease.

Key findings
The study focused on households with cases showing symptom onset between September 12, 2020, and March 15, 2021, before vaccines were available to the public. To determine the effect of the isolation centre on household transmission of COVID-19, the researchers tracked households where someone infected with COVID-19 used the Toronto Voluntary Isolation Centre (TVIC) and compared them to similar households (in terms of age, gender, household size, neighbourhood, etc.) where people self-isolated at home. Researchers monitored how many other people in the household became infected within 28 days, using a statistical model to understand the differences between the two groups. Here’s what the researchers discovered:

• Households that used a voluntary isolation center saw a 50% lower risk of COVID-19 transmission compared to similar households that followed routine self-isolation guidance.
• The use of the isolation centres was particularly effective when:
• First cases quickly checked into the isolation centre (within 2 days of developing symptoms)
• Households were from neighborhoods with more household crowding
• Households were larger in size

Future directions
Future studies could examine the barriers to using isolation centres and explore how to make them more accessible and appealing during the initial stages of a future pandemic, especially to populations at higher risk.

Public health implications
This study suggests that voluntary isolation centres are an effective public health tool that should be included in future pandemic preparedness planning. During a pandemic and prior to the availability of vaccines, public health should focus on making isolation centres more available, especially for high-risk households, and ensure that cases are quickly identified, tested, and referred to these centres with strategies to encourage their use. PHO provides expertise, support and resources for the prevention and control of infectious diseases.