Still many unanswered pandemic questions
As predicted, we are in the middle of a second wave of COVID-19.
As of Dec. 23, the world has seen more than 78 million confirmed cases and 1.7 million deaths.
One of the few successes to emerge has been the creation of COVID-19 vaccines in record time. But vaccination will not provide immediate relief.
There are many unanswered questions about the efficacy of the vaccines. For instance, vaccine studies mostly tracked how many of the individuals that were vaccinated became sick. It is not known if the vaccinated individuals can still carry the virus asymptomatically; vaccinated people don’t show symptoms, but some may continue to have the virus in the nose and throat that can replicate and spread. We also don’t know about the chances of reinfection or long-term immunity.
Infection with COVID-19 comes with a risk of death and puts strain on our health-care system, but there is also a risk of long-term health effects. The bottom line is we cannot let our guard down: we need to continue wearing masks, keep our physical distance, wash our hands, and avoid crowds and indoor events in poor ventilated areas.
As the weather grows increasingly colder, reducing our options for outdoor activities and gatherings, we need to consider how the disease spreads indoors and the importance of ventilation.
AVOIDING CROWDED INDOORS
The evidence for aerosol transmission is overwhelming. Three of the most important factors that determine the risk of exposure are proximity to people, duration of the exposure and air quality. When the three are combined, the risk is higher, as seen in numerous super-spreader events.
COVID-19 spreads through inhalation of the virus. An infected person breathes out aerosols that can remain suspended in the air for up to three hours. Transmission indoors can be about 20 times higher than outdoors.
We should think about SARS-CoV-2, the virus that causes COVID-19, spreading like cigarette second-hand smoking in a closed space. The amount of particles inhaled close to the source is higher, but, with time, the smoke will fill the whole room and everybody will breathe the contaminated air.
Indoor transmission by aerosols has been recognized by the U.S. Centers for Disease Control and Prevention and the Public Health Agency of Canada. The World Health Organization recommends avoiding indoor spaces whenever possible and ensuring proper ventilation in the fight against COVID-19. We need to take these recommendations seriously.
My research team is interested in different aspects of indoor ventilation. We are combining building information modelling and indoor viral spread models to study different strategies to return to indoor gatherings and address potential future outbreaks.