Practising 3Ws reduces infection rates dramatically

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

25 October 2020

Since January this year, health authorities the world over have been repeating the 3Ws song on a daily basis. The 3Ws are the three simple actions that protect from contracting Covid-19. They are: (1) Wash your hands regularly, (2) Wear a mask whenever you’re outside your house, and (3) Watch your distance from other people – stay at least 1m away from them.

The question is: how effective are these simple actions in protecting against the disease. I have seen several studies attempting to measure the risk reduction factors of each of these measures. Washing hands at least five times daily reduces the infection rate by about 40 per cent.

That is, when two groups are compared – one that washes hands five times daily versus another one that does not – then, after a period of time, the number of infections in the first group is 60 per cent that of the second one.

 Wearing a mask is even more effective. The infection rate among people who wear the masks is just 25 per cent of those who don’t. And the chance of infection when you are one metre away is only 20 per cent compared to staying at close proximity.

When these three protective actions are combined, the net effect is dramatic. It is 60 per cent of 25 per cent of 20 per cent. That is 0.6 x 0.25 x 0.2 = 0.03. In other words, when you observe these three measures, the chances of getting infected are just 3 per cent of not doing them at all.

That is, you will reduce the probability of infection by 97 per cent. So, if you ever doubted whether the 3Ws can help you, the numbers are clear.

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Positivity rate” is the new catch phrase in the fight against Covid-19. But what is it and what does it tell us about the disease?

Positivity rate is simply the proportion of tested individuals who turn out to have the disease. If, say, 500 people are tested and 100 are found to be positive, then the positivity rate is 20 per cent.

As to what it tells us about the spreading of the disease is still a mystery to me! The only thing I can read out of this number is how well the authorities are targeting their test subjects. But that has nothing to do with the prevalence of the disease!