Virus Simulator

Dyson's new CoVent ventilator system. Image courtesy of Dyson. Ventilators are devices that are part of intensive care unit beds. They push air in and out of a persons' lungs when they are unable to breathe for themselves. With Covid-19 attacking airways and lungs, they are a vital part of the battle to keep critically ill patients alive long enough to recover. When the UK government is warning about swamping the NHS, a large part of this is running out of ventilators. Before the Covid-19 pandemic, the UK had around 8000 ventilators. That is 6.6 per 100,000 people. If you have tried the simulator on this web page, this is the number used to asses if the virus has overwhelmed the health service. The reason why the UK changed it's strategy from a single moderate social distancing effort, to multiple lockdowns over the next 12-18 months is to avoid overwhelming ventilator capacity. New ventilator order The government has just placed a new order for 10,000 ventilator

Photo by Kat J on Unsplash When most of us think of the risks from Covid-19, we think about catching the disease and ending up in hospital. This risk is real and serious, whether you are a young fit 20-something or older with underlying health conditions. For some people, there are further risks, both from the disease itself, and from the actions we take. The UK government recently released advice specifically aimed at domestic abuse safe accommodation . Multiple families can live in the same accommodation, so it is important that staff at such accommodation take great care to avoid bringing the infection in. There is also a need to assess how isolation can occur if someone does show Covid-19 symptoms. It may be that only one family needs to isolate themselves, or the entire accommodation might need to be isolated. Expected increase in incidents The police have said that they expect a significant increase in domestic abuse cases. With families required to isolate, and with

Reproduction number tells us how rapidly a virus spreads or declines. The reproduction number, (sometimes Rn or R0 for short) is a key value describing how rapidly a virus spreads or declines. It is the average number of new people that a carrier will infect. If this number is exactly one, then every carrier gives the disease to one other person before they recover. That person goes on to give it to one other person before they recover, then they give it to one other person before they recover and so on. This would mean that the disease was stable and neither spreading, nor dying out. If Rn is bigger than one, then more people are catching the disease than are recovering. The disease will spread exponentially if it is left unchecked, like branches on a tree one splitting into two and splitting again. Conversely if Rn is less than one, more people are recovering from the disease than are catching it and the disease is declining. What determines reproduction number? Reproduction

Exponential growth occurs like branches on a tree. Each branch grows more branches, which grow more branches, so the rate of growing branches gets faster every year. People often assume that exponential growth is rapid growth. This isn't necessarily the case. Something can grow fast, but not exponentially, or something can grow slow and exponentially. Exponential growth means that size of something is multiplied by a number in any given time. This compares to steady growth where the size has a number added to it in a given time. For example, if you have a garden and hate mowing your lawn, you may think your grass grows fast. Every week it grows by 2 centimetres. Although this is fast it is not exponential - it is always growing at the same speed. Every week, 2 centimetres. Imagine instead, if you had exponential grass, which doubled in length every week. If it starts of at 5 millimetres tall, then in the first week it only grows 5 millimetres - slower than our normal grass

The experts use computer simulations to predict how a pandemic or epidemic will spread through the population. But for most people, the idea of a computer simulation being used to make decisions that affect all our lives, seems very distant. It’s potentially difficult to understand how these simulations relate to the real world and hard to decide if they are giving useful predictions. I feel like the best way to understand something is to have a go. So that's what I have done, and I thought I would give anyone else who wishes, the opportunity to have a go as well. So I have coded up my own small simulation of a spreading virus. You can download it here! Download it to your laptop or PC and just double click it to get going. Unfortunately I’ve never written apps for phones, so there isn’t an app version - you will need a laptop or PC. What this is and what this isn’t This is what scientists refer to as a toy model. This means it is a simulation that captures some of the basi