How effective are infection control techniques at reducing COVID-19 transmission?

Infection control measures like handwashing, wearing masks, protective clothing or gloves, are widely endorsed as a means of curbing the spread of COVID-19. But just how effective are they at reducing transmission of the virus?

UTS Research Professor and respiratory disease expert Professor Brian Oliver says that there are several important things to keep in mind in answering this question.

“Firstly, none of these measures present a silver bullet,” he told Hospital + Healthcare.

“There is no magic anti-viral mask out there. Although N95 respirators (aka P2 masks) come in different varieties for a number of purposes, none are designed specifically for pandemics. Even if they were, they would only need to be 95% effective to satisfy safety tests.”

Secondly, the efficacy of these measures can be compromised drastically when used imperfectly, Oliver said.

“It is unlikely that a patient wearing a mask would wear it 100% of the time. Most patients remove their masks to eat, answer the phone or to sneeze into a tissue,” he said.

Fomites released from sneezing and coughing onto surfaces are believed to be the primary route of transmission of the COVID-19 virus. They can live on solid surfaces for up to three days and penetrate handkerchiefs onto skin. This is why regular handwashing is believed to be one of the most effective infection control methods.

However, the efficacy of handwashing also depends on user behaviour, Oliver explained.

“A lot of people simply don’t wash their hands often enough, or for a sufficient duration. Everybody needs to wash their hands before touching their face, including their mouth, skin and eyes.

“To remove fomites from your skin, at least a 20-second wash, in warm water, is recommended. You need to really lather up the soap with exaggerated movements that cover all the surface area of your hands, wrists and underneath your fingernails,” he said.

Oliver said that all types of soaps are effective at killing or removing fomites. Antibacterial soaps are not superior to others, since COVID-19 is not a form of bacteria.

However, he warned that hand sanitiser gels can be less effective when applied to greasy or dirty hands.

“Grease on your fingers acts as a barrier, which the hand sanitiser struggles to penetrate. Using soap and water to clean greasy or dirty hands would be a better alternative,” he said.

Although no infection control method is 100% effective, Oliver emphasised we should persist with these techniques.

“A typical, healthy person would need to be exposed to 1000 virus particles to be infected with the common cold. If we reduce the number of particles through these infection control techniques, we can reduce the number of people contracting the virus,” he concluded.

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