The Problem with Assessing Covid-19

The Covid-19 outbreak has taken the world by surprise but it is a previously expected risk. Nature has been shouting warnings at us for decades with nobody listening. Those who claim it is a hoax or not a problem are still doing so, and no amount of figures to say otherwise will ever convince them. Their decision is made, and they’re always going to stick to it whatever happens. As far as they’re concerned all figures produced will be fake. But for those trying to figure out what is happening the problem is trying to work out some reasonable guidelines to see how we are doing.

We are still at the start of the outbreak for most countries, but how do we assess how things are going? The simple answer would be to calculate who has died from the disease against the number of recorded infections, but this simple ratio doesn’t allow for a continuing set of new infections, and would only be accurate when all things are finished, maybe in 10 years time. So how can we get a handle on the situation?

An estimate can be garnered from working out the timeline of infections.

A rough guide to a typical Covid-19 infection is:

Day 0              Infection

Day 4-12        Felling slightly off

Day 13-21      Feeling normal


Day 0              Infection

Day 4-5          Noticing you have an infection.

Day 6-21        Recovery

But in cases of serious illness from it:

Day 0              Infection

Day 4-5          Noticing you have an infection.

Day 6-18        Hospitalisation

Day 19-30      Recovery


Day 0              Infection

Day 4-5          Noticing you have an infection.

Day 6-24        Hospitalisation

Day 25-50      Recovery

For cases of mortality:

Day 0              Infection

Day 4-5          Noticing you have an infection.

Day 6-10        Hospitalisation

Day 11-13      ARD

Day 14-18      Death


Day 0              Infection

Day 4-5          Noticing you have an infection.

Day 6-12        Getting worse

Day 13-18      Death

If we think of the disease as a set of processes in a factory, and the part we are interested in as the number of deaths as defective items, we have a number of inputs, outputs, storage areas, and production lines.

The inputs:

Day 0 the raw materials arrive. Our inspector doesn’t notice all of them, some being under tarpaulins, and they can’t be bothered of have time to look underneath. On day 4-5 somebody comes along and puts them through the first part of the process.

One of the lines is fed, and the stuff goes through without even being inspected at any point. The second line the inspectors record the numbers going into the system on day 5, re-routing the items either to the normal, hospital, or ignored lines recorded on day 6. On the hospital line the operators route the items to the normal hospital route and go onto the normal route, or the ARD route on days 11-13.

The outputs

The unnoticed items come out at the end on about day 21.

The normal items come out at the end on about day 21.

The ignored line ends in either leaving the system around day 11-17 and recorded 12-18, or finishing on day 21.

On the normal hospital line they end that line on days 19-25, going back onto the normal line ending on days 21-50. The ARD line then mainly leaves the system on days 14-18 and are recorded on days 15-19.

The items are constantly going into and leaving the system at various rates of increase depending on social restriction damping the inputs, and levels of awareness giving more inspection.

So how do you assess what is going on at any stage?

The best way of doing this is probably using a 5-day range. Shorter than 5 days and the numbers won’t be that significant for time, longer than this and the numbers will be warped too much by additional inputs and outputs to be assessed as they are at the moment always arriving and leaving.

So, a 5-day input will start at day 0, only becoming noticeable by records at day 5. The course of the illness takes about 21 days, so that group will leave the records in the system normally 16 days later, unless there are major complication when they will leave early around day 16, recorded on day 17.

So, if you are at day 21 the majority will have left the system, mortality being recorded mainly at 4 days before.

So, if you are at a date x then the calculation would be:

Mortality in this area = Total mortality at date x-4, minus the date recorded x-4-16, the total mortality that ended in the previous period.

Divided by:

Cases falling into this area = Total number of cases at date x-16, minus the date recorded x-16-21, the total number of cases that ended in the previous period. You will then need to multiply by 21/16 to compensate for the differing cycle lengths.

You are still going to have an overlap of values as the virus infection length is 21 days and the mortality overlap length is 16 days, two separate cycles, which you can’t normally cater for in pure date calculations, but the difference is 5 days of variation, hopefully not a really significant figure.

So, as of 29/10/2020 the total world numbers of cases is 43,323,453, but 16 days prior to this on the 13/10/2020 it was 38.348,128, and 21 days prior to that on 22/09/2020 it was 31,749,508, so for the last period the number was 6,601,620 cases.

The current mortality is 1,182,541, but 4 days ago on 25/10/2020 it was 1,158,810, 16 days prior on 09/10/2020 being 1,071,176, giving 87,634 deaths. Multiply by 21 and divided by 16 for the equalisation of the different length cycles, total cases being over 21 days and total mortality being over 16 days:

This would give 87,634/6,601,620*21/16=1.74% general current mortality.

For the UK, as of 29/10/2020 the total numbers of cases is 965,340, but 16 days ago on the 13/10/2020 it was 634,920. 21 days prior on 22/09/2020 it was 403,551, so for the last period the number was 231,369 cases.

The current mortality is 45,955, but 4 days ago on 25/10/2020 it was 44,896, 16 days prior on 09/10/2020 being 42,679, giving 2,217 deaths.

This would give 2,217/231,369*21/16=1.26% UK general current mortality.

It’s hard to work out the cycles of virus as it rapidly expands into new areas and lockdowns will dampen the figures, so early figures from each country will be variable between when in those states in the society, quite haphazard, but the potential range for mortality for the world seems to be between 1.74-10%. If the UK with a median age of about 40.6 is an example, then the potential range can be between 0.75%-10%, which seems to be 0.75% for being in total lockdown, and up to 10% if there was no lockdown or restriction.

Because of the cost and logistics involved with new antiviral drugs and treatments they are not really regarded as something that can alter the effect substantially, vaccines possibly having a similar damping effect to lockdown and restrictions, but their effectiveness or not is still to be tested in the field and an unknown quantity, ignoring the scientific hype and marketing. Typical costs for a lot of these new drugs are in the tens of thousands of dollars per course, some being over a million. For 7.8 billion people who might need them at some time in their life it works out to quite a lot. All of the ‘quick fix’ cheap remedies have quite often come down to being little different to placebos when looked at objectively, and some actually causing more problems than they cure, possibly leaving the door open for other viruses and bacteria to have a go. Strengthening one area while weakening another is not a good practice, and all drugs have an effect, possibly quite undesirable over time, especially if used long-term, a case that may become necessary with this new virus.

If the vaccines don’t deliver what is promised, then it’s likely that everybody in the world will eventually get the disease at some time, probably when the economies can no longer support the lockdowns, so may be in the worst shape to provide support for it. With the numbers still increasing local quick and dirty lockdowns will give time, but it may be robbing peter to give to paul, especially if things don’t go according to plan. So it’s really a question of balance, realising the problem may not quickly go away, managing a poor situation as best as can be done, rather than reacting in panic to each what is a predictable event. You can fence yourself in, but you can’t fence the world out.

Hopefully the vaccines will deliver, but if they don’t in the way they are intended and it gets worse, or becomes just a fact of modern life lasting for decades, what is plan B?

Looking at the common cold, where 14% of colds are caused by the older 4 strains of coronaviruses, we keep on catching them, so the new ones, Covid-19, SARS and MERS are likely to be similar but with different characteristics. Covid-19 crept under the radar, and we can only hope that the others won’t take advantage of it, spreading in disguise, things like measles progressively on the increase due to the anti-vax movement. But if the immunity damping ability of measles turns out to be a fact, then we may be in for a long hard dangerous haul.

As of today, 15/11/2020, in the world there have been 54.6 million cases, increasing at +2.7% per day, and 1.32 million deaths. The UK is now reporting 1.37 million cases and 52,000 deaths. It has an estimated 475,000 known active cases. So about 0.7% of the world is known to have been infected so far, 2% of the UK according to the approximate official estimates. As of 15/11/2020 there have been 35.3 million tests returned in the UK, about 32.6 antigen tests and 2.66 million antibody tests, 1.37 million, 3.9%, or 1 in 26 testing positive, 96.1%, 25 out of 26 people testing negative. At 80% accuracy that gives a figure between 18,500 and 29,000 new cases in the UK a day. World Mortality based on the approximate official estimate of known cases is 2.4%. but UK mortality based on estimates of approved recorded figures is 3.8%. About 30% of known cases are still active in the world, 35% in the UK. My estimate of the likelihood of data for the UK would be about 78,000 deaths and 3.4 million cases, but the mortality range could be anything from 51,000-145,000, 2 million unnoticed or undetected, so a mortality rate of about 2.3%.

Mortality, if you backtrack the infective period over the deaths that are likely to have resulted from that period from recorded cases it gives a recent average of 1.91% for the world and 1.24% for the UK, the current figure being 1.85% for the world and 1.7% for the UK, various conditions such as lockdowns affecting the figures, but a 2% mortality figure would be a good guideline to work from as it has the largest sample numbers and the longest term. If you do the same for the US figures the average is 1.74% and the current figure is 1.48%.

The average for deaths in the UK is 82, similar to the median figure, which suggests most of the people dying are very elderly, but this signifies that half who die are below this age and half above, but the proportions in different countries are as below show a potential for varying results dependent on the current characteristics of a community:

UK DeathsUS DeathsMexico Deaths
Under 553%5%38%
Under 606%8%51%
Under 6510%12%63%
Under 7015%16%77%
Under 7524%21%86%
Under 8037%23%93%
Under 8555%27%97%
Under 9077%40%99%
90 and over100%100%100%

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