Tag Archives: Climate

On ageing populations, “development” and Covid-19

There is increasingly clear evidence that older people are more likely to die from Covid-19 than are younger people: on 17th February,  the China CDC weekly report showed that among the cases known in China by then, the ≥80 age group had the highest case fatality rate at 14.8% (with the 70-79 age group being 8% and the 60-69% age group being 3.6%); and in early April, the WHO Regional Director for Europe highlighted that over 95% of Covid-19 deaths occurred in those over 60, with more than 50% in those aged 80 years or older.  In the UK, the Office for National Statistics (ONS) reported in mid-April that mortality from Covid-19 increased consistently with age, with only about 13% of deaths being of people under 65.  Significantly, though it noted that men had a death rate double that of women; more recent ONS reports have also shown that (when taking into account age) Black men and women were more than four times as likely to die from Covid-19 then were those of White ethnicity, and that such differences in mortality were partly a result of socio-economic disadvantage.  These data are stark, and are as yet still not fully explained.  As people grow older, they generally have greater comorbidities, and it may be the impact that Covid-19 has on these other health problems that is more significant than age itself.

However, this is an important reminder that Covid-19 is primarily an old-people’s disease.  It is striking to recall that in 1951 life expectancy at birth in England and Wales was only 66.4 for men and 71.5 for women; in 1901 the figures were 48.5 and 52.4 respectively (ONS, 2015).  Put simply, people born 70 years ago were not expected to live to the age at which most people are now dying from Covid-19.  This has important ramifications, and raises very difficult questions.  Have people, perhaps, become over expectant about longevity?  Will Covid-19 temper our aspirations to live for ever?  Will it be a check on the ambitions of companies such as Novartis, Alphabet and Illumina to extend life well beyond 100 years (CNBC, 2019)?  Is the main problem of Covid-19 that most people living in the richer countires of the world have become too cosy in their expectations of living to a ripe old age?

Implications for Europe and north America: too many old people

Thought experiments can be a helpful means of highlighting challenging issues.  Suppose, for example, that there had been no lockdowns in Europe and North America.  It seems very likely that substantial numbers of elderly people would have died already (see projections by epidemiologists at Imperial College which suggested that without mitigation strategies Covid-19 would have resulted in 40 milllion deaths globally in 2020).  If a vaccine or cure is not found, then it still seems likely that large numbers of elderly people will indeed die in Europe at an age well short of what they and their families have grown accustomed to expecting.

However, think of the impact that this will have on the economy and health services.  Once large numbers of elderly people have died, national pension bills will fall, the burden on health services will be reduced, the percentage of people within the economically productive age range will increase, and the economic vitality of their countries will be revitalised.  If Covid-19 (or its successors) become an everyday part of life, the economic “burden” of older people will be dramatically reduced.  It is scarcely surprising that rumours  circulated about the intentions of UK government policy in early- to mid-March.  As Martin Shaw noted at the time, it had been credibly reported that the “Government’s strategy was ‘herd immunity, protect the economy and if that means that some pensioners die, too bad’; or as summed up even more succinctly by a senior Tory, ‘Herd immunity and let the old people die’”.  Whilst the government strenuosly denied this, there is a realistic logic to the idea that letting large numbers of old people die would have clear economic benefits, and would avoid the very considerable costs that are accruing as a result of economic shutdown.

I should stress that this is definitely not a scenario that I would want to encourage or endorse, but in the early part of May, the balance of popular opinion (or the influence of the business community and mainstream media in the UK) does seem to be swinging towards a view that the costs of lockdown are too high to continue to protect the elderly, especially in those countries where there have already been very high death rates (as in Belgium, the UK, France, Italy, Spain and the USA).  Yet, the 20th and latest Imperial College Covid-19 report  concludes for Italy that “even a 20% return to pre-lockdown mobility could lead to a resurgence in the number of deaths far greater than experienced in the current wave in several regions”.

Implications for Africa and South Asia: youthful countries

The real purpose of this reflection, though, is to consider the implications of the above arguments for some of the economically poorest countries in the world.  Data about Covid-19 infections and deaths in Africa and Asia are likely to be even less reliable than they are in Europe, and the countries in these continents are in any case much earlier in their encounters with Covid-19 than are those of Europe.  Recent reports, for example, suggest that the real number of deaths related to Covid-19 may be many times the number that are currently reported (see The Guardian‘s recent report on Somalia).  Nevertheless, we do have relatively accurate data about the demographic structures of most countries in the world.  The chart below therefore shows the relationships between current density of Covid-19 deaths and the percentage of population aged ≥65 for a sample of countries.[i]

Screenshot 2020-05-08 at 08.33.35

This graph is striking, but difficut to interpret (and can be misleading), mainly because most countries in Africa and Latin America are only at an early stage in their Covid-19 outbreaks.  We simply do not know how many deaths they are likely to witness, and few models have yet been published that predict the likely outcomes.   However, with the very notable exceptions of Japan, Greece and Germany, it re-emphasises that high percentages of Covid-19 deaths are mainly found in those countries that have more than 15% of their populations aged ≥65.  Even Brazil, where the death rate is currently growing rapidly, is still nowhere near at the level of mortality that has occurred in Europe and the USA.  The quite remarkable achievement of Greece, with only 147 deaths by 7th May, is also highly noteworthy because despite a fragile health service and an elderly population it has managed to achieve something that most other European countries have been unable to do.  Most commentators suggest that this is mainly because it imposed a dramatic lockdown even before the first deaths were recorded.

Most countries of the world have intiated lockdowns, and these are having particularly significant impacts on the poorest and most marginalised who can least afford it. An obvious question therefore arises: if Covid-19 mainly affects the elderly, should countries with young populations (such as most of those of Africa, Asia and Latin America) follow the “older” countries in imposing strict lockdowns that will have damaging effects on their economies and the livelihoods of those who can least afford it?  Put another way, are the mitigating actions of European and North American countries, where more than 15% of their populations are ≥65, relevant to economically poorer countries with less than 10% of their populations in this age group?

It is far from easy to answer this.  Perhaps the very small numbers of people reportedly dying in Africa at present is only because the coronavirus has not yet gained a grip, and any loosening of the mitigating measures would unleash the pandemic at a scale similar to that seen in Europe.  The WHO, for example, has warned  that the Covid-19 pandemic might kill as many as 190,000 people in Africa in the year ahead (Al Jazeera, 8th May), with many more dying subsequently.  This may well be true, but there is at least a chance that the youthful populations of Africa will be better able to deal with Covid-19 than have done the older populations of Europe.  It must, though, be emphasised that many younger people who are infected with Covid-19 do indeed have serious illnesses, and some die.  We also do not yet know the long-term health impacts of this coronavirus.  Moreover, the evidence that socially disadvantaged people are also more likely to die than their more affluent neighbours further suggests that the poorest and most marginalised in these countries may well have higher death rates.

As I have illustrated elsewhere, there is some (but by no means conclusive) evidence that environmental factors may also play a role in limiting the spread of Covid-19.  If the environments of Africa and South Asia are indeed not particularly conducive to the spread of Covid-19, then their youthful populations might not need to endure the very tight lockdowns imposed in many European countries. That having been said, the rapidly increasing number of infections and deaths in Brazil (with 121,600 cases and 8,022 deaths as of 7th May), which has physical environments and climates similar to many parts of western and southern Africa, does not bode well for the future spread of Covid-19 in Africa.

Conclusions

In conclusion, there remains much that is unknown about how Covid-19 spreads and who it affects most damagingly.  The evidence from Japan, Greece and Germany shows that even when countries do have a high percentage of elderly people, it is still possible to contain and limit the spread of Covid-19, thereby preventing very large numbers of deaths.  The abject failures of governments in countries such as the UK and Belgium to manage the pandemic and save lives likewise indicate how not to respond to the pandemic.  The governments of African and South Asian countries, with their youthful populations who appear less likely to suffer severe symptoms, may well therefore have an advantage over their European counterparts.  If they can draw lessons about what has worked and what has failed, then they are also in a good position to bounce back swiftly from the economic harm caused by economic and social lockdowns.

 


[i] The selected countries included the ten most populous countries in the world (in descending order of total population, China, India, USA, Indonesia, Pakistan, Brazil, Nigeria, Bangladesh, Russia, Mexico), a selection of European countries with mixed trajectories (listed alphabetically, Belgium, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, Switzerland), and a diverse sample of African (alphabetically, DRC, Egypt, Kenya, Rwanda, South Africa, Tanzania), and other (alphabetically, Iran, Japan, South Korea, Turkey) countries.

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The influence of environmental factors on Covid-19: towards a research agenda

Considerable attention was paid in the early days of the Covid-19 pandemic to its spatial distribution in the hope that environmental factors might be found to play a key role in influencing its spread in two ways: by restricting it to a narrow band of countries with specific environmental factors; and hoping that a rise in temperature in the summer would kill it off.

  • Researchers at Maryland University (Sajadi, M.M. et al., 2020) thus used maps of the early stages of Covid-19 to suggest that it spreads more easily in cold, damp climates, and that its highest incidence would be between latitudes 30-50 N.  At the time, I suggested on 3rd April that there were too many anomalies for this to be valid, that it was only based on limited data (where the coronavirus had spread by early March 2020) and that it was necessary to understand better the actual physical processes involved.  However, the idea that there might be environmental factors that will control Covid-19 still persists.
  • Likewise, in the early days of the pandemic there was much optimism that the new coronavirus might act in similar ways to some of its predecessors and be seasonal in character, waning in the summer months when it gets warmer.  Again, this was in part based on the timing of its outbreak (in China in December 2019 ) and its rapid spread through Europe with an approximately similar timing to seasonal flu.  However, many experts were cautious about this possible scenario (see Jon Cohen in Science, 13th March 2020, and Alvin Powell in the Harvard Gazette, 14th April 2020).

Nevertheless, the much more rapid spread of Covid-19 in Europe and North America than in Africa and South Asia has led some to continue to argue that the devastating impact of lockdown in countries nearer the equator, particularly on the lives of some of the poorest people living there, may be un-necessary if this pattern can indeed be explained by environmental factors.  The lockdown has already been partially rolled back, for example, in countries such as Pakistan (with some factories reopening on 12th April , and congregational prayers at mosques durong Ramadan being permitted from 21st April) and South Africa (with initial steps being taken to reopen the economy on 1st May).  Clearly, the rate and distribution of the spread of Covid-19 is influenced by many factors, including government policies (with the UK performing especially badly, see my recent post),  demographic characteristics (with the elderly being particularly vulnerable), population distribution (spreading slower in sparsely settled areas), characteristics of the several strains and mutations of the Sars-Cov-2 coronavirus (summary in EMCrit), and the inaccuracy and unreliability of reported data about infections and deaths (see my comments here).

The role of environmental factors remains uncertain, despite a considerable amount of research (see systematic review by Mecenas, P. et al., 2020 – thanks to Serge Stinckwich for sharing this) which has sought to draw conclusions from the distribution of cases in parts of the world with different climates, and has suggested that cold and dry conditions helped the spread of the virus whereas warm and wet climates seem to reduce its spread.  A more recent study by Jüni et al. (8th May 2020) has claimed that epidemic growth has little or no association with latitude and temperature, although it has weak negative associations with relative and absolute humidity.  Unfortunately, very few studies have yet sought to do experimental research that actually measures the survivability and ease of spread of Sars-Cov-2 under different real-world environmental conditions.  Moreover, if as appears likely, most infections actually occur indoors, it is not the external climatic conditions that will influence rates of infection but rather the artifical environments created indoors through heating and ventlaltion systems that will be of most significance in influencing its spread.

Two related approaches to this challenge are necessary: identifying its survivabililty in a range of different environments (and surfaces), and analysis of the effect of different environments on the distance that it can be spread by infected people.

Research on the survivability of Sars-Cov-2 in different contexts

Several reported studies have explored the stability of the new coronavirus on different surfaces.  In a widely cited study, van Doremalen et al. (13th  March 2020) suggested that the stability of HCov-19 (Sars-Cov-2) was very similar to that of Sars-Cov-1 (the SARS outbreak in 2003), and that viable virus could be detected as follows:

  • in aerosols up to 3 hours after aerosolization
  • up to 4 hours on copper
  • up to 24 hours on cardboard and up to 47-72 hours on plastic and stainless steel.

This important study has subsequently been used as the standard estimate for the survivability of the coronavirus.  However, it was undertaken in the USA under very specific relatively humidity (for aerosols at 65%; for surfaces at 40%) and temperature conditions (for both at 21-23o C) (See also more recently, van Doremalen et al. 16 April 2020).  A rapid expert review of Sars-Cov-2’s survivability under different conditions (Fineberg, 7th April 2020) notes that the number of experimental studies remains small, but that elevated temperatures seem to reduce its survivability, and that this varies for diffferent materials.  Nevertheless, Fineberg emphasises that laboratory conditions do not necessarily accurately reflect real-world conditions.  In referrring to natural history studies, he also emphasises, as noted above, that conflicting results have emerged because such studies are “hampered by poor quaity data, confounding factors, and insufficient time since the beginning of the pandemix from which to draw conclusions” (p.4).

If a better understanding of Sars-Cov-2’s survivability in different parts of the world is to be gained, it is therefore essential urgently to undertake real world studies of its viability on similar surfaces in various places with different temperature and humidity profiles.

The dispersal distance of Sars-Cov-2

The standard advice across many countries of the world is that people should maintain a minimum distance of 2 m (in some countries 1.5 m) between each other to limit the spread of Covid-19 (see, for example, Public Health England).  This is double the WHO’s advice for the public, which is to “Maintain at least 1 metre (3 feet) distance between yourself and others. Why? When someone coughs, sneezes, or speaks they spray small liquid droplets from their nose or mouth which may contain virus. If you are too close, you can breathe in the droplets, including the COVID-19 virus if the person has the disease“.  The 2 m figure was adopted early by some CDCs, and appears to be more of an approximate early guess (based on the previous Sars-Cov-1 outbreak) that has taken root, rather than an accurate scientifically based figure.

Since then, more rigorous research has been undertaken, much of which suggests that 2 m may not be enough. Setti et al. (23rd April) thus note that Sars-Cov-2 has higher aerosol survivability than did its predecessor, and that a growing body of literature supports a view that “it is plausible that small particles containing the virus may diffuse in indoor environments covering distances up to 10 m from the emission sources”.  They also conclude that “The inter-personal distance of 2 m can be reasonably considered as an effective protection only if everybody wears face masks in daily life activities”. A particularly interesting laboratory based study a month previously by Bourouiba (26th March 2020) provides strong evidence that the turbulent gas clouds formed by sneezes and coughs provide conditions that enable the coronavirus to survive for much longer at greater distances: “The locally moist and warm atmosphere within the turbulent gas cloud allows the contained droplets to evade evaporation for much longer than occurs with isolated droplets“.  She concludes that the “gas cloud and its payload of pathogen-bearing droplets of all sizes can travel 23 to 27 feet (7-8 m)”.  Furthermore, another study by Blocken et al. (9th April) noted that the 1.5 m – 2 m distance was based on people who were standing still, and that there could be a potential aerodynamic effect for people cycling and running.  For someone running at 14.4 km/hr the social distance in the slipstream might be nearer 10 m.

Such studies have been controversial (for a summary, see Eric Niiler in Wired, 14th April), but they highlight that in practice:

  • the “safe’ distance between people is unknown;
  • there is little strong scientific evidence for the 1 m – 2 m recommendations for social distancing; and
  • this distance is highly likely to vary in different environmental contexts.

Not enough conclusive reseach has yet been undertaken on the extent to which environmental factors, such as humidity, pressure, altitude, wind and temperature actually affect how far Sars-Cov-2 will disperse, and at what infectious dose (see Linda Geddes, NewScientist, 27th March 2020, where viral load is also discussed; see also ECDC, 25th March 2020).  It seems likely, though, that dispersal will indeed vary in different conditions, and thus in different parts of the world.  We just don’t yet know how great such variability is.

The latest systematic review published in The Lancet, and cited in The Guardian (2nd June 2020) sugggests that distance does matter, and that not only is 2 m safer than less than 1 m, but also that face masks can indeed reduce substantuially the risk of infection.

Towards a research agenda

This post has emphasised that we actually know remarkably little with certainty about how Sars-Cov-2 physically survives and disperses in different environmental contexts.  This has hugely important ramifications for the spread of Covid-19 in different parts of the world, and thus the mitigating policies and actions that need to be taken.  If, for example, Covid-19 does not survive in hot humid conditions, and is also dispersed over shorter distances in such circumstances, then it might be possible for governments of countries where such conditions prevail not to have to impose such stringent social distancing requirements as those that have been put in place in Europe.

Urgent experimental research is therefore required in real-world environments on:

  • the survivabililty of Sars-Cov-2 in a range of different physical environments (and surfaces), and
  • the effects of different environments on the distance that it can be spread by infected people.

A standard protocol and methodology for such research should be created that could then be used collaboratively by scientists working in different parts of the world to address these crucial issues.  Contrasting environments that would warrant the earliest such research (given the high number of economically poor countries therein) would include: high altitude savanna (as in the Bogotá savanna, and the much lower montane Savanna of the Angolan scarp), tropical and subtropical savanna (as in parts of Brazil and Kenya), tropical rainforests (as in Indonesia and Brazil), semi-arid and arid landscapes (as in much of northern and south-west Africa, the Arabian peninsula, and parts of South Asia).  It is also very important to undertake such resaerch both in urban and rural areas, and indoors as well as outside.  If scientists can indeed co-operate to provide a swift answer to the questions raised in this post, then it would be possible to provide much more tailored advice to governments concerning the mitigating measures (including the use of masks) that they should be taking to protect the highest number of people while also maintaing essential economic activity.

[Updated 8th May, 12th May, 30th May 2020 and 2nd June]

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Filed under Africa, Asia, Covid-19, Geography, India, Pakistan