The predictions for the spread of SARS-COV-2 have been modelled over and over in different given scenarios. The Washington Post had a good visual simulator There are some pretty amazing graphics that have helped us all understand how movement of people is likely to affect outcomes and the disease spread of Covid-19.
What do some of the words and phrases actually mean?
Pandemic is not a word used lightly. It means a disease that has spread across a wide population of people – across continents or worldwide. Other pandemics in history have been the 1918 flu, smallpox, TB, 2009 H1N1 (swine flu).
The important thing to know about a disease is how quickly it spreads and how harmful it is.
Flatten The Curve
Flattening the curve is not to prevent people getting Covid 19, this cannot really be prevented now.
Why can’t it be prevented?
- You can be contagious without symptoms
- You can be contagious with very mild symptoms
- Children are experiencing few symptoms but are passing on the virus
- The virus is persisting on surfaces for long periods of time.
What is an incubation period ?
The time it takes from contracting a virus to exhibiting symptoms.
For SARS-COV-2 it’s 2-14 days.
During the incubation period you can shed the virus and infect other people.
Why we keep seeing: #socialdistancing
Social distancing will mean that the healthcare system, which in the UK already runs to capacity (think of the headlines about waiting lists, hours on an ambulance, sleeping in corridors), has time to cope with the rapid influx of unwell people that need hospital support. It literally means putting distance between people – working from home, exercising at home, online shopping. It’s been highlighted by the cancelled six nations matches, the cancelled marathons that people have trained so hard for. It means hardship from loss of earnings, loss of customers, lack of business, in some cases – loneliness. It also gives hope. Hope that with mitigating spread, suppressing the outbreak, acting as a community , that things can flourish again.
Even if 80% of the population have mild symptoms, the 14% with severe illness or 6% with critical illness – needing ventilators, intensive care support will result in a collapse of the NHS.
Doctors will have to make impossible decisions about who gets to be ventilated, so like in Italy, parameters will be drawn up to aid in this – age, comorbidities (other illnesses).
Here we are just talking about Covid-19. People will still need emergency operations, thrombolysis for their heart attacks, treatment for asthma attacks, antibiotics for sepsis caused by urinary tract infections, there will be no capacity for this either. Patients will be experience this to as a health service that doesn’t have the capacity to care for them.
It seems we can stem this tide though. We can get off one curve and onto another – that’s what all this talk of flattening this curve and social distancing is about. This is why it’s so important. The fewer people moving around the better. Some people will have to leave their homes. But, those of us that can socially distance really should – regardless of age. We need to come together in a different way, and understand what ‘it takes a village’ really means. We all have things to offer, a video lesson to a kid thats not in school now on how volcanoes are formed, or a recipe showing someone that doesn’t really cook what they can do with some garlic, tin tomatoes and a tin of sardines..
We can still support our local businesses who have innovatively started dropping shopping and food to our homes, our gyms that are programming home workouts for us and offering to loan us kit to use at home. Self isolating/social distancing comes at tremendous economical cost, no doubt, but there seems to be little alternative. How will the people with no homes to go to cope? What impact on the thousands of people that require social care for activities of daily living, the short term scenario is pretty bleak for many.
The report highlights suppression strategy scenarios for the UK showing intensive care unit (ICU) bed requirements. The black line shows the unmitigated epidemic. Green shows a suppression strategy incorporating closure of schools and universities, case isolation and population-wide social distancing beginning in late March 2020. The orange line shows a containment strategy incorporating case isolation, household quarantine and population-wide social distancing. The red line is the estimated surge ICU bed capacity in GB. The blue shading shows the 5-month period in which these interventions are assumed to remain in place. (B) shows the same data as in panel (A) but zoomed in on the lower levels of the graph. (Source: WHO collaborating Centre / MRC GIDA / J-IDEA)
Home isolation of cases – staying at home for 7 days if you have symptoms – cough, temperature, breathlessness that doesn’t require medical attention.
Home quarantine – all household members of those with symptoms of the disease remain at home for 14 days from the start of those symptoms
Social distancing – a broad policy that aims to reduce overall contacts that people make outside the household, school or workplace by three-quarters.
The graphic and terms above are from a report written by the MRC Centre for Global Disease Analysis at Imperial College London – : Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand. It suggests that in a first scenario -slowing the spread, which involves combining home isolation of cases, with home quarantine and social distancing in the over 70’s we could reduce demand on the NHS by two thirds and reduce deaths by half.
However, it goes on to say that even with this package of disease mitigation, the impact on the NHS would still be overwhelming, estimating 250,000 deaths.
It is thought that even greater measures are required – social distancing of the entire population, home isolation of cases, household quarantine of family members, and added school and university closure. Tightening and relaxation of these rules would be in response to the disease progress.
What is the R Nought (R0) ?
SARS-COV-2 has an R0 of between 1.5 and 3.5. It’s thought that one infected person infects between 2-4 others.
The formal definition of a disease’s R0 is the number of cases, on average, an infected person will cause during their infectious period.
- If R0 is less than 1, each existing infection causes less than one new infection. In this case, the disease will decline and eventually die out.
- If R0 equals 1, each existing infection causes one new infection. The disease will stay alive and stable, but there won’t be an outbreak or an epidemic.
- If R0 is more than 1, each existing infection causes more than one new infection. The disease will spread between people, and there may be an outbreak or epidemic.
It only applies when :
- no one has been vaccinated
- no one has had the disease before
- there’s no way to control the spread of the disease
Some framework for understanding this:
The R0 for measles is – 18-20
The R0 for 1918 “spanish flu” – 1.4-2.8
The R0 for H1N1 ( swine flu) in 2009 – 1.2-1.6
R0 is basically how easy it is to spread the disease. What it does not take into account is how harmful it is. As per the graphic in my last post, Covid -19 is easily spread and relatively harmful.
Covid-19 currently has a mortality rate of between 0.6-2%
Seasonal flu has a mortality (death) rate of 0f 6-20 times less than this.
Narrowing down these figures is going to be helpful, but it requires time. These figures also only related to deaths in people we know were tested and positive for the virus.
Death rates rise rapidly for people with coexisting illnesses- especially hypertension (high blood pressure), Type1 or Type 2 diabetes, up to 8%.
Given what we know today, this is our call to arms. If we allow Covid-19 to out run our healthcare resources it may not be the virus that causes our demise. If you’re having one last drink in the pub before the “lock down” you’re missing the point entirely.
Woeful under swabbing of everyone, including healthcare staff with symptoms, gives us a skewed idea of disease progress. But, again, other countries , the pandemic models and what our experts are telling us are from where we must take our lead.
We, all of us will be affected by these days to come, we will all experience loss. The Stoics would tell us to learn from the past, to turn obstacles into ways to progress. These are decisions that are no longer to be made by us. I would tend to agree.
“The chief task in life is simply this: to identify and separate matters so that I can say clearly to myself which are externals not under my control, and which have to do with the choices I actually control. Where then do I look for good and evil? Not to uncontrollable externals, but within myself to the choices that are my own…”
— Epictetus, Discourses, 2.5.4–5