Tag Archives: South Africa

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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My favourite South African Wines…

ThelemaA visit to the Cape Province of South Africa last week in order to help select wines for the Athenaeum provided a great opportunity to learn something about  recent changes in the wine industry in the Cape and to taste some of the really excellent wines that are now being produced there.  It is some 40 years since I last visited Stellenbosch and Paarl, and it is great to see the quality of wines now being made in the region.

Thanks to Stuart and George who arranged the itinerary, and the hospitality of many amazing wine makers, we had the privilege of tasting nearly 200 wines from Stellenbosch, the Cape Peninsula, Franschhoek and the hinterland of Hermanus.  While this represented only a small fraction of the many wines now being made in South Africa, it did highlight three significant things for me:

  • First, the quality of the wines has improved very dramatically indeed over the last 15 or so years.  There are without doubt now some really excellent wines being made in South Africa, and they are very good value indeed, with many of the best wines being priced at under ZAR 250 (£15) a bottle.  We scarcely tasted a poor bottle, and it was difficult to choose those that I preferred best for my list of favourite wines below!
  • Second, South African wine makers have definitely learnt and understood the importance of terroir. Given my geographical wine “upbringing” in Burgundy, I have always argued that the physical environment has a very important role in determining the character of a wine, and it is good to see the increasing differentiation that now exists in the planting locations of different grape varieties in the Cape area.  Many of the wines we tasted emanated from some of the cooler vineyard locations, higher up on the mountain slopes, in windier locations, and closer to the sea.
  • Third, South Africa’s vineyards have to be amongst the most beautifully situated in the world, with many of them being in very picturesque locations, as I hope the pictures below illustrate.  Whilst leafroll virus is a serious problem for grape-growers, it does have the merit of turning vines a beautiful red colour in the autumn!

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Despite the pleadings of my colleagues, I am still not convinced by many of the Chenin Blanc wines we tasted, perhaps with the exception of some of the sweet dessert wines.  I’m sure that some of my reticence stems from tasting too many rough Steen wines when I was younger!  While I recognise that modern good quality Chenin Blanc wines are indeed being made, I simply don’t particularly like them, finding the astringent flavours that I encountered in my youth all too often still to be present.  Likewise, I have to confess not really to liking wines made from the Pinotage grape.  All too often they too retain bitter flavours, and I found many of those we tasted to be rather unbalanced and poorly structured – with one delicious exception!

So, to conclude, my favourite wines, in alphabetical order of producers were:

  • 4Buitenverwachting (with MD Lars Maack)

    • 2009 Christine – excellent open fruity nose; 14.5% alcohol; rich, rounded, soft tannins; red fruit flavours; 45% Cabernet Franc contributes to tobacco and chocolate flavours (with 45% Cabernet Sauvignon and 10% Merlot); well balanaced and good length
  • Chamonix (with Wine-maker Gottfried Mocke)

    • 2011 Pinotage – a very unusual wine made in a similar style to Ripasso, combining fresh wine refermenting with air dried grapes; half-picked very young and undergoes carbonic maceration; other half desiccated and refermented with first picking; grown at 440 m 9on Greywacke soils; 14.5% alcohol; kept mainly in one-year-old Pinot Noir barrels; dark red with complex green and dark fruit flavours; very soft tannins.
    • 2012 Chardonnay Reserve – 13.5% alcohol; 14 months in 228 l French oak; 30 year old vines which show character and personality; 80% barrel fermented with 20% in 600 l concrete eggs, which enable wine to be oxygenated and the lees stay in suspension for longer than using other fermenters; high acidity early grapes are put into concrete, with later pickings going into barrels; always goes through malo-lactic; tries to pick fruit at lower sugar levels to make wines more in a Burgundian style; 65% new oak used for this vintage, which remains very evident; need to keep for some time.
  • 5Cape Point (with Wine-maker Duncan Savage)

    • 2011 Late Harvest Noble 8 – only made when conditions are right, with some 2000 half bottles being produced in 2011; 160 grams residual sugar; 10.5% alcohol;  Sauvignon Blanc and Semillon botrytised blend; rich balanced fruit flavours; good length; acidity balances out the rich fruit; dried apricot flavours.
  • Delheim (with Viticulturist Vic Sperling)

    • 102009 Vera Cruz Shiraz – we had the last bottle in the cellar sadly; produced from bush vines; 14.5% alcohol; rich, intense fresh red fruits on the nose; fruity flavours of plums and jam; good length and complexity; their Vera Cruz wines are only made in years when the fruit is good enough; a powerful wine to be kept for a while.
    • 2013 Edelspatz Noble Late Harvest – botrytised Riesling from Simonsberg Mountain; good acid balance; not overly rich; classic slight petrol nose, but well structured and luscious flavours of honey and apricots.
  • Glenelly (with Wine-maker Luke O’Cuinneagain)

    • 12012 Oaked Chardonnay – light golden colour; blanche toasted 500 l barrels designed to keep as much natural fruit flavour as possible; fresh with good fruit expression; distinctive pear flavour, with slight citrus touches; richer and softer than their unoaked Chardonnay; good structure and depth.
    • 2010 Syrah – designed to be like a northern Rhône wine; 100% whole bunch fermented; purple-red colour; very clean, with slight smell of bacon; white pepper and floral aromas; relatively low alcohol at 13.9%; soft tannins, but needs time to develop.
  • Klein Constantia (Wine-maker Matthew Day)

    • 22013 Sauvignon Blanc – made with free-run juice from grapes from across the property; very pale in colour; up-front nose of gooseberry and blackcurrant leaves; 4 months in steel on lees; fresh in mouth, with balanced acidity on edge of tongue; quite light and eminently drinkable
    • 2008 Vin de Constance – classic dessert wine made from Muscat de Frontignan grapes, left to dry on the vine; good rich flavours of candied orange, with other fruits including a slight pineapple taste; good depth and length; balanced acidity.
  • Meerlust (with Chris Williams, Cellar Master)

    • 62012 Pinot Noir – a serious wine; lovely rich nose; has been made since 2004 on coolest hilltops, which catch the breeze being only 3 kms from the sea; vines grown on decomposed granite; picked at 4-6 tonnes per hectare; vinified in small batches, some with natural fermentation; has an interesting liquorice nose; quite soft tannins; needs keeping for several years.
    • 2009 Rubicon – excellent Bordeaux blend style wine (69% Cabernet Sauvignon, 20% Merlot, 10% Cabernet France and 1% Petit Verdot); very rich and intense rich blackcurrant fruit flavours; complex; good length; well structured; definitely for keeping.
  • Newton Johnson (with Bevan Newton Johnson, MD)

    • 32012 Family Vineyards Pinot Noir – really good wine, clean, well structured, medium length, and rich complexity of Pinot flavours resulting from use of grapes from three adjacent vineyards (20% from Mrs. M, 30% from Block 6, and 50% from Windansea); first made in 2008/9; red fruit rather than vegetal.
    • 2012 Windansea Pinot Noir – Pinot Noir from a single vineyard which has more clay than adjacent ones, giving a deeper colour; a bit closed and more restrained than the fruitier more open Mrs. M and Block 6; well structured with good acid balance; excellent finesse; red and black berry fruits.  A really excellent wine.
  • Spier
    • 21 Gables Sauvignon Blanc – hand harvested; made from grapes grown in Durbanville near the Atlantic on red gravel and clay soils; nose of new mown hay; acidity clearly felt at edge of tongue; but well structured; rich complex flavours of gooseberry and slight asparagus; 13.5% alcohol.
  • Thelema (with Cellar Master Gyles Webb)

    • 82011 Cabernet Sauvignon “The Mint” – made from the first Cabernet Sauvignon vines they planted, with eucalyptus trees nearby, which give the wine a distinctive minty nose and flavour; mid-red colour; well-balanced and good structure; will be long-lived.
  • Vergelegen (with Wine-maker Andre van Rensburg)

    • 2011 Merlot – the first 100% Merlot wine made at Vergelegen since 1998; although Andre sees himself mainly as a Cabernet Sauvignon producer, he believes they have the environment to produce excellent Merlot; lovely soft nose and very gently tannins; still a bit young, and lacking a bit in length, but overall very pleasant.
    • 72010 DNA – Cabernet Franc does well at Vergelegen, but the yield needs to be reduced down to around 4 tonnes per hectare; aim is to pick the fruit as late as possible; mid-red, quite intense colour; 65% Cabernet Franc, Merlot 21% and Cabernet Sauvignon 13%; fantastic high notes on nose; very soft tannins; not as strong a smoky nose as I would have expected with this amount of Cabernet Franc; wine is designed to be fruity rather than green.  Wine is made in recognition of Andre’s respect to Cheval Blanc, with the DNA often being thought of as being similar to terroir.  Others might think that it is short for “Dickhead ‘n Arsehole”!  Incidentally, the label is not a fingerprint, but rather the contours of a hill!

Finally, I have long appreciated the work that Charles Back has done at Fairview, and particularly his BootLeggerscommitment to social change in the region.  In 1997 he helped establish The Fairvalley Workers Association, which aims to help workers at Fairview to have their own land, and he was also the driving force behind the Fairvalley wine brand that is owned by the Workers Association, with profits from the sale of their wines (made using cellar facilities at Fairview, and FairTrade certified) being used to support community development initiatives.  Being in South Africa enabled me to access further wines that it is difficult to get in the UK, and so I particularly enjoyed the opportunity to explore the shelves of Bootleggers in Fourways Crossing and purchase additional wines, including some of Fairvalley’s remarkably good value 2009 Cabernet Sauvignon, which was delicious with boerewors, as well as  a bottle of Fairview’s 2010 Goat-Roti (Syrah/Viognier blend) that went especially well with barbecued fillet steak!

For those looking for somewhere quiet and relaxing to stay while exploring the vineyards of the Cape, I thoroughly recommend Majeka House, just outside Stellenbosch, which also houses the excellent Makaron Restaurant!

 

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Jordan Wine Estate, Stellenbosch

It is some 40 years since I was last in Stellenbosch – and how it has changed!  Today, I had the privilege of being introduced to the wines of Jordan Wine Estate by Gary and Kathy Jordan – in the company of some good friends.  It is great to see the impact that UC Davis has on far-flung parts of the world, and also to meet wine-makers who combine expertise in geology and economics to produce some really very good wines!  Terroir is definitely alive and well here.  Sadly, I’m not yet able to share the flavours of the wines virtually, but I hope that the images below capture something of the beauty of this part of South Africa, as well as the care and attention to detail that marks out wine-making at Jordan Wine Estate!  Have to say that I particularly enjoyed the 2011 Cobblers Hill – and the lunch!

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