While the speedy, effective roll-out of vaccinations is fundamental to South Africa’s economic recovery, the Covid-19 Delta variant has changed the way the disease can be passed on.

To make all indoor spaces as safe as possible, sufficient ventilation to reduce the risk of Covid-19 transmission must be ensured, says ventilation organisation GreenFlag Association chairperson Norman Khoza.

While vaccines dramatically reduce the risk of becoming very sick or dying from Covid-19, vaccinated people exposed to the Delta variant can still become infected, but not show any symptoms or pass on the disease.

“The most effective way to prevent transmission is through providing adequate ventilation in indoor spaces. People should also continue to wear masks, sanitise and maintain physical distancing. Doing all these things dramatically reduces the chance of becoming infected,” he says.

People in indoor spaces are 20 times more likely to become infected with Covid-19 than in outdoor spaces. Improving ventilation in a closed space significantly lowers the chance of catching the virus. Good ventilation means bringing fresh outdoor air into an indoor space and removing stale air out of the space.

South Africa is currently in its third wave of Covid-19 transmissions, fuelled by the so-called Delta variant, which is twice as contagious as previous variants, according to the US Centers for Disease Control.

“GreenFlag Association-affiliated scientists are calling on the owners and managers of public spaces, including public transport, restaurants, shops, workplaces, gyms and even hospitals and vaccination sites, to prevent super-spreader events. The scientists estimate that up to 75% of the Delta variant in South Africa is being spread in public and private transport.”

GreenFlag Association panellist and Fellow Chartered Member of the South African Institute of Safety & Health Dr Garth Hunter studied the spread of Covid-19 in public transport and determined that opening the windows in a vehicle can reduce the transmission of the virus dramatically, with carbon dioxide (CO₂) tests showing that fresh air flushes out the virus-laden air in less than 60 seconds, reducing infection rates by up to 90%.

Using the example of a taxi, measurements show that if one passenger is infected with Covid at the starting point of the journey, up to 80% of the other occupants could become infected by the time they reached the final stop, assuming a duration of ten minutes or more.

The longer the exposure to the contaminated air, the greater the viral load, or dose, the passengers will be exposed to and the greater the chance of infection.

"This scenario also holds true for indoor spaces, such as vaccination centres. Closed-up restaurants, and even hospitals, carry a much higher risk of Covid-19 transmissions than well ventilated or outdoor spaces, says Hunter.

“Health officials must ensure proper ventilation at vaccination sites to prevent its spread.”

“If you have to be indoors or in a vehicle with other people, ensure all windows are open. The more fresh air that circulates through the space, the quicker any airborne virus will be removed from the room,” says Khoza.

“South Africa needs to implement vaccination and understand the role ventilation plays in reducing the transmission of Covid-19. Our message is clear: if we want to beat this pandemic, we need to focus on the double Vs, namely vaccinate and ventilate,” he says.