A large increase in testing with the introduction of at home rapid testing could explain why case numbers appear to be climbing. Although, these cases tend to be milder, caught earlier, and may even be representative of asymptomatic cases, as we know its estimated a significant portion of cases are asymptomatic.
It was initially hypothesised that the falling death rate was the result of a 'Lead Time Bias', where there is a large gap between symptoms and fatalities, making survival time appear longer.
It is clear now that despite these caveats, the Case Fatality Rates (CFR) and the Infection Fatality Rates are fewer than in the early stages of the pandemic.
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Public Health England¹ (PHE) estimates of the CFR's for people aged 80 and over, the average CFR was 29% in week 18, fell to 17% in weeks 19 to 27, and from mid-July onwards the CFR was 11%. A decrease is seen in the age group of 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 this virus has declined in all age groups. The older age groups drive the overall reduction. The new cases are predominantly in younger people who have a better outcome.
In the early stages of the pandemic in Germany, deaths mirrored cases, but the more recent trend is for cases to increase whilst deaths 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 the 30th of August it had more than doubled to 1,402 a day. 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.
The matter most certainly deserves some reflection to extract key learnings and debunk speculation and misinformation.
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 nearly 90% of new cases are now identified in the community through walk-through and drive-in testing.
Professor 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.
Do Social and Physical 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 viral load they are exposed to. The three D's, Dose, Distance, and Duration also impact 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 present fewer symptoms, even asymptomatic. Whether this results in a differing quality of immunity 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.
According to Dr Veena Raleigh, a senior fellow at the King’s Fund¹² (an independent charitable healthcare body) most of this group are taking care not to get infected.
Are There Fewer Vulnerable People Left?
So far 21,775 of those who have died in the UK were care home residents¹³ yet the total care home population alone is 330,000. Another 350,000 receive care at home, so we can deduce that there are still a large number of individuals at high risk of serious illness.
Do Hospitals Have Better Treatment?
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, resulting in hospitals and clinicians being less overwhelmed.
Corticosteroids such as dexamethasone and hydrocortisone also contribute to improved recovery by calming the body at times of extreme immune response which in itself can be the result of genetic predisposition.
Has Vitamin D From Sunshine Helped?
Some people have been advocating for vitamin D as a form of 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, its important to also consider that transmission rates soared in the US during summer, contradicting this study.
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 65-80% 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 introduction of vaccines, as there is no such thing as natural herd immunity in nature. Herd immunity should lead to fewer people becoming infected, but not necessarily to less serious infections.
Immunity for other respiratory viruses such as the common cold can last for months but then fade, 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 and some more severe.
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 more or less dangerous.
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National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
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Oke, 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/
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Coronavirus (COVID-19) in the UK, 19 October 2020: https://coronavirus.data.gov.uk
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Coronavirus (COVID-19) in the UK, 19 October 2020: https://coronavirus.data.gov.uk
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National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
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Oxford COVID-19 Evidence Service, (n.d.): https://www.cebm.net/oxford-covid-19-evidence-service/
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Coronavirus (COVID-19) in the UK, 19 October 2020: https://coronavirus.data.gov.uk
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National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
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Spiegelhalter, E: How much 'normal' risk does Covid represent? 21 March 2020: https://medium.com/wintoncentre/how-much-normal-risk-does-covid-represent-4539118e1196
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Pujadas, 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
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National COVID-19 surveillance reports, 23 April 2020: https://www.gov.uk/government/publications/national-covid-19-surveillance-reports
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Raleigh, V: UK’s record on pandemic deaths, 4 September 2020: https://www.bmj.com/content/370/bmj.m3348.full.print
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Care 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/
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Oke, 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/
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Northwestern 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
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University 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