Why are COVID-19 deaths falling even as cases are rising?

Dr Dominique Eggermont, Medical Director, Dubai

 

Besides the increasing dispersion of the virus in our communities, the rising amount of testing could explain why more cases are being uncovered. They tend to be milder, caught earlier, and may even represent the fortuitous finding of an asymptomatic case as  a significant percentage of cases are asymptomatic. 

At first we were tempted to believe that the falling death rate was the result of a so-called Lead Time Bias, where the virus kills its victims several weeks after getting infected, after which it may still take a few weeks for the reporting to be processed and digested for public consumption. 

 

To illustrate this perhaps one should consider having a look at the obituaries-pages in the newspapers (not much reporting lag-time there) and compare the numbers over the past few months to the same period over the last few years.  

 

Today it is abundantly clear that, even though “Deaths” lag “Cases”, the Case Fatality Rate (CFR) and, even better, the Infection Fatality Rate, is less than in the early stages of the pandemic.

 

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Public Health England¹ (PHE) estimates of the CFR over time show that for people aged 80 and over, the average CFR was 29% up to week 18, fell to 17% in weeks 19 to 27, and from mid-July onwards the CFR was 11% – a decrease of 61%. An even larger decrease is seen in the ages 60-79 with the average CFR being 9% in March/April falling to 2% in July/August. 

 

According to Jason Oke, Daniel Howdon, and Carl Heneghan’s analysis of German Data², the fatality rate from COVID-19 has declined in all age groups, and the older age groups drive the overall reduction. The new cases are predominantly in younger people who have a better outcome. 

 

In the early phase of the pandemic, deaths in Germany mirrored cases, but the recent trend is for cases to increase whilst deaths continue to decline. 

 

The UK Government’s COVID-19 dashboard³ shows that cases have risen steadily from their lowest point on July 1st when the rolling seven-day average was down to 574. By 30th August it had more than doubled, to 1,402 a day and yet over the same period the fatality rate had steadily declined from a rolling average of 37.4 per day to 4.6 per day⁴.

 

And so, speculation abounds that the age of those infected is playing a part, that social distancing and the shielding of vulnerable people is having an impact, that there are no more vulnerable people left to die, so on and so forth.

 

The matter most certainly deserves some reflection, and what follows attempts to explain and perhaps even debunk… 

 

Does more testing mean more mild cases are discovered?

PHE figures⁵ show that in March and April, testing was limited almost entirely to hospitalised patients and health care workers, whereas today nearly 90% of new cases are identified in the community through walk-through and drive-in testing. 
 
 
Prof Carl Heneghan at Oxford’s Centre for Evidence-Based Medicine⁶ also suggests that tests have become more sensitive, now able to detect small traces of viral antigenic material in those who had already recovered weeks prior to being tested.

 

Are new patients less likely to die because they are younger?

The CFR for people older than 70 is 100 times higher than for those younger than 40⁷.

 

According to  PHE⁸, more than two-thirds of new cases in the last week of August were people under 40, a figure which is likely to be linked to looser rules on socialising, whereas at the peak of the pandemic, only 28% of cases were younger than 40. 

 

According to Professor David Spiegelhalter the risk of dying from COVID-19 doubles at roughly every six years of age⁹, so the 2,042 people in their 20s who caught COVID-19 in the last week of August were probably unlikely to need treatment and become a fatality.

 

Do social (as in “stay away”) and physical (a personal space issue) distancing measures mean viral loads are lower?

A recent Lancet study¹⁰ found that the amount of virus present when a patient was tested did predict how likely patients were to die.

 

Some research shows that wearing masks and keeping away from other people reduces the amount of virus they are exposed to. 

 

There may indeed be a link between physical distancing and the amount of virulum one is subjected to as, not unlike radiation – another invisible enemy – Dose, Distance, and Duration affect the amount of inoculation. 

 

Some even suggest, speculatively, that frequent small inoculations generate low-level immunisation and that this could be the reason why some people are less sick, even asymptomatic. Whether this confers a lesser quality immunity still remains to be proven. 

 

Are vulnerable people still shielding?

According to the PHE¹¹ data only 374 people over 70 tested positive for COVID-19 in the last week of August compared with 10,770 in the first week of April.

 

Don’t be fooled as people in this age group are still as vulnerable.

 

According to Dr Veena Raleigh, a senior fellow at the King’s Fund¹², an independent charitable healthcare body, most of them are taking care not to get infected.

 

Are there fewer vulnerable people left?

So far 21,775 (and counting) of those who died in the UK were care home residents¹³ yet the total care home population alone is 330,000 and another 350,000 receive care at home - so there are still large numbers at higher risk of serious illness.

 

Do hospitals have better treatments?

From published analysis¹⁴ Oxford Researchers show that in June people with the virus were four times less likely to die in hospital than in April.
 
 
Several factors play a part here as non-invasive devices such as CPAP replaced ventilators, infection control measures improved as hospitals created COVID-19 wards, whilst hospitals and clinicians do better when not overwhelmed.
 
 
Corticosteroids such as dexamethasone and hydrocortisone also contribute to improved recovery by calming the body at times over-reaching immune response which in itself can be the result of genetic predisposition.
 

 

Has vitamin D from sunshine helped?

Some people have been advocating vitamin D as a treatment for respiratory diseases for nearly a century.

 

Researchers now suggest a link between vitamin D deficiency and COVID-19 death rates¹⁵. 

 

A recent study by the University of Chicago last week showed people with vitamin D deficiency were almost twice as likely to test positive for the virus¹⁶ as those with healthy levels. 

 

However, transmission rates soared during summer in the US, so any broader health impact seems limited so let’s just say the jury is still out on that one.

 

And perhaps melatonin also deserves some attention.

 

Antibody testing studies have estimated that about 13% to 17% of Londoners have had the virus, a much higher figure than seen elsewhere in the UK, but much lower than the 65 to 80% that is assumed as the lowest level to be needed to achieve herd immunity. 

 

Are we starting to see herd immunity?

Let’s not forget that the term “Herd Immunity” was first coined with the apparition of vaccines, as there is no such thing as natural herd immunity in nature.

 

Immunity for other respiratory coronaviruses such as the common cold can last for months but then fades, so there is no guarantee that those who have been infected by SARS-CoV-2 will be able to brush off COVID-19 forever. There are increasing reports documenting re-infections – some of these second infections are milder than the original, however some are more severe.

 

Also, herd immunity ought to lead to fewer people becoming infected, rather than hoping for less serious effects of infection.

 

And then, who’s to say that the SARS-CoV-2 will not, upon individuals having been infected, cause cancers to develop later, as is for example already the case with HCV and HPV.

 

Is COVID-19 getting weaker?

Geneticists have discovered that there is some evidence COVID-19 is evolving, but so far there does not seem to be any solid evidence that it is becoming less dangerous – or, thankfully, more deadly either.

 

To conclude we can safely say that this cryptic devil is stretching our capabilities, be it intellectually or otherwise. 

 

Vaccines don’t save lives, vaccinations do, but the vaccine is still a way off, in the hope that it’ll really work, safely.

 

So, in order to keep the fatalities related to COVID-19 low, we have today as first recourse prevention, and subsequently treatment.

 

Find out how we can support you during this pandemic here.

 

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¹National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
²Oke, J: Declining COVID-19 Case Fatality Rates across all ages: analysis of German data, 9 September 2020: https://www.cebm.net/covid-19/declining-covid-19-case-fatality-rates-across-all-ages-analysis-of-german-data/
³Coronavirus (COVID-19) in the UK, 19 October 2020: https://coronavirus.data.gov.uk
⁴Coronavirus (COVID-19) in the UK, 19 October 2020: https://coronavirus.data.gov.uk
⁵National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
⁶Oxford COVID-19 Evidence Service, (n.d.): https://www.cebm.net/oxford-covid-19-evidence-service/
⁷Coronavirus (COVID-19) in the UK, 19 October 2020: https://coronavirus.data.gov.uk
⁸National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
⁹Spiegelhalter, E: How much 'normal' risk does Covid represent? 21 March 2020: https://medium.com/wintoncentre/how-much-normal-risk-does-covid-represent-4539118e1196
¹⁰Pujadas, E: SARS-CoV-2 viral load predicts COVID-19 mortality, 6 August 2020: https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30354-4/fulltext
¹¹National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
¹²Raleigh, V: UK’s record on pandemic deaths, 4 September 2020: https://www.bmj.com/content/370/bmj.m3348.full.print
¹³Care homes in England had greatest increase in excess deaths at height of the COVID-19 pandemic, 30 August 2020: https://www.stir.ac.uk/news/2020/august-2020-news/care-homes-in-england-had-greatest-increase-in-excess-deaths-at-height-of-the-covid-19-pandemic/
¹⁴Oke, J: Declining death rate from COVID-19 in hospitals in England, 24 June 2020: https://www.cebm.net/covid-19/declining-death-rate-from-covid-19-in-hospitals-in-england/
¹⁵Northwestern University: Vitamin D levels appear to play role in COVID-19 mortality rates, 7 May 2020: https://www.sciencedaily.com/releases/2020/05/200507121353.htm
¹⁶University of Chicago Medical Center: Vitamin D deficiency may raise risk of getting COVID-19, study finds, 3 September 2020: https://www.sciencedaily.com/releases/2020/09/200903133007.htm
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