The current coronavirus pandemic is being treated as the worst for a bit more than a century. Therefore, as a biologist, I cannot sit by while reading so much confused commentary on the current situation. The media is full of confusion; and sometimes even the quoted experts are not being sufficiently clear. Note that I am not talking about the blatant mis-information and moralizing currently appearing on Facebook and Twitter, which is nothing more than personal opinions from often ill-informed people. I am talking about the professional media, who in many cases seem not to understand the topic, at least to date.
To me, the main source of confusion is about the difference between the virus itself and the disease that it causes. They are not the same thing, by any means; and it matters greatly to the discussion, and to how we should react to the pandemic. Sometimes the media are writing about the one and sometimes about the other, even in the same sentence, and even using the same words. How can the general public possibly be helped by this? In this post, I try to remedy this by distinguishing which bit of the discussion refers to which.
I have some background in infectious diseases, so I thought that it might be worthwhile to try to clarify the biology, for readers of this blog. This is a long post, but it will give you something to read while you are in quarantine. It is based on what I have read, and understood, in the professional literature, as well as expert commentary. I offer no personal advice for any of you, just commentary, which you should take on its own merits — I have a PhD not an MD.
The virus
So, to get things clear, the virus is officially called SARS-CoV-2. It is one of several types of coronavirus, some of which have proven difficult for humans over the past few decades (eg. SARS-CoV and MERS-CoV).
The virus has a small genome enclosed by a lipid (fat) layer. There are currently two known strains, meaning that they have slightly different genomes. It is not yet known whether the difference has any important consequences for their infective behavior.
We act as the living host for the virus, and normally it cannot function outside a host. However, the lipid membrane of cornoaviruses allows them to easily survive (inactive) in the outside world — in the case of this new one, for up to 3-5 days on some hard surfaces, like metal, glass or plastic (other coronaviruses can last even up to 9 days).
In order for you to become a host to the virus, you need to get one (or more) into your body through some of your so-called mucous membranes. It cannot get through your skin, but it can get in through your nose, mouth and eyes. So, you can pick it up through the air from someone within about 2 yards / meters of you, if they cough or sneeze, which produces respiratory droplets. Alternatively, if you touch a virus-infected surface, such as a door-handle, a stair-rail, or a trolley in a supermarket, then it will be on your hands. People touch their faces with their hands at least once every 3 minutes or so (on average), in which case you run a big risk of infecting yourself.
You can now see why you are being given instructions to keep away from each other (air transmission), and to wash / disinfect your hands often (surface transmission). Soap, alcohol and even bleach all seem to work to clean your hands. You could also try rinsing your face, when you come indoors. Perhaps the toughest issue for people is the length of time during which a virus-infected surface remains dangerous — regular and thorough cleaning is the only remedy.
The disease
But all of this has nothing to do with the disease. A disease is a reaction by your body to some other organism, be it a virus, a bacterium, a fungus, a plant or an animal. Most disease-causing organisms are harmless to almost all other organisms. That is, each type of virus has only a limited range of hosts in which it can survive; and, even then, many hosts are not actually badly affected.
The primary host, however, can be seriously affected, in many cases. In our case, our response to coronaviruses is a respiratory inflammation, which in its worst form is a type of pneumonia. This pneumonia may even be fatal, especially for people whose lungs have been adversely affected in the past, and are therefore not in prime condition. The same situation is the case of other coronaviruses, like SARS-CoV (causing Severe Acute Respiratory Syndrome) and MERS-CoV (causing Middle East Respiratory Syndrome). In the current pandemic, SARS-CoV-2 causes the disease we have called Covid-19 (the “d” in that name stands for “disease”).
So, it is the disease that is called Covid-19, not the virus. This makes all the difference to understanding what people are talking about in the media. The main point is that being infected with the virus does not necessarily mean that you will develop the disease.
The experts are now beginning to suspect that, in fact, many people do not develop the disease, even after they get the virus. These symptom-free people can still pass the virus on to others, of course; and those others may very well develop the disease. That is, having the virus does not necessarily make you “sick”; but, unbeknownst to them, people should keep away from you.
There is nothing unusual about this situation for infectious diseases. For example, when I was young, my father developed tuberculosis (which is caused by a bacterium). My sister, brother and I were all tested, of course, to check for exposure. My brother’s test indicated that he had acquired the bacterium, but he did not develop the disease; neither my sister nor I had picked up the bacterium.
The current situation
This should help clarify the current media information. All of the data being bandied about in the media refer to the disease (Covid-19), not necessarily the virus. We can tell when people develop the disease, because they have certain symptoms (including fever, cough, shortness of breath). So, the experts can tell us what percentage of the people have developed the disease, and what percentage of those have subsequently died.
At the moment, it seems that roughly 80% of Covid-19 cases are mild (with flu-like symptoms), and the people can recover at home. Another 15% of cases are severe, developing a pneumonia, and often require hospitalization. The remaining 5% become critical patients, often with respiratory failure, septic shock, and even kidney failure; and these people may very well die.
So, getting the disease is unpleasant but not dangerous for most people. The other 20%, on the other hand, will have problems. Fortunately, depending on your age and medical condition, the virus may not be a big issue for you, at all.
Clearly, the most densely populated areas are generally the ones with the biggest infection rates. Person to person spread is much greater when more people live near each other. Spread is also greater when more people are in a small space, such as at public gatherings and workplaces. This may yet turn out to be the most easily spread virus we have encountered.
There are sufficient data to indicate a fairly direct relationship between disease severity and patient age — 70+ years old is the major risk group, with a death rate of c. 20%. Pre-existing medical conditions also seem to be very important for actual survival, notably cardiovascular disease and diabetes, but also lung conditions (eg. from smoking, or asthma) and hypertension (high blood pressure). That is, being older makes you more susceptible to Covid-19, but it is the combination with other medical conditions that will do you in. (Note: given this information, I am on the border of the main pandemic risk group.) It seems that healthy lungs are a key survival characteristic. This benefit cannot exist as we get older, of course, because of all of the colds, flus, etc, that our lungs have previously had to cope with.
On the other hand, what the experts cannot tell us yet is how many people have picked up the virus. It now seems clear that this might well be a large number, far greater than was previously thought (it was originally estimated at 1.5-3.5%). People with only mild, or even non-existent, symptoms seem to exist, especially among the young. In some cases, the symptom-free period is relatively short, but in others it is much longer. So, the reported Covid-19 data are missing three groups of people, of unknown size:
- those who show no symptoms or are only mildly ill (unreported cases)
- those who have been missed, because there hasn’t been enough testing (unreported cases)
- those who are currently incubating the virus but have not yet shown symptoms (pre-clinical cases); this period can be up to 14 days.
In order to get this information, we would have to test a large number of people, irrespective of whether they have ever had symptoms. The medical world is currently over-loaded in most Western countries (where the infections are concentrated), and there is neither the person-power nor the required test kits to do this. Indeed, even the current testing has caused chaos, especially in the USA, which has had a woefully low testing rate (hampered by delayed and faulty test kits), as it requires DNA testing (slow and expensive).
So, it may still be a long time before we could even begin the task of collecting infection data. On the positive side, test kits have now been announced that would allow us to more easily do the required testing. These do not test for the presence of the virus itself, as do the currently used tests. Instead, they test whether your body has reacted to the virus. In response to infectious diseases, we produce antibodies, which help us counter-act the disease-causing organism. These antibodies make us safe from future infections by the same organism. The new tests look for the presence of these antibodies; and this is much more efficient and cost-effective than the current tests. (Note: this is the basis for the tuberculosis test that I mentioned above.)
Some countries have shown a resurgence of infections, after a first boom in Covid-19 cases (eg. Singapore, Taiwan, Hong Kong), which is not an unexpected scenario. The problem is the existence of the three groups of people listed above as currently unreported and pre-clinical cases. There may be many more infected people running around any well-populated country, ready to infect new people when travel restrictions are lifted, and the unexposed people come in contact with the infected ones. So, influenza-like epidemics are known to start with a bad (and dangerous) burst, calm down for a while, and then break out again.
It is for this reason that there are suggestions that the circulation of the virus may last for up to a year, in total, with maybe 80% of people infected, and up to 15% of people hospitalized with the disease. This does not mean that the current disease (Covid-19) situation will continue for a year, but that the virus (SARS-CoV-2) will still be around.
Recent experiences
What can we learn from the pandemic so far, that might tell us how to react now? Different countries have applied different response policies, apparently based on differing cultural traditions and social behaviors. We know some strategies that have worked so far, and some that have not, depending, I guess, on your own cultural expectations.
The Chinese reacted rapidly to the spread of the virus, once they had officially acknowledged that it exists. They were immediately authoritarian, and severely limited personal travel, and this seems to have been effective at restricting long-distance spread — their disease rate is low (compared to many countries), although given the massive size of their population that still means a lot of people developed the disease. For several days now, no new confirmed or suspected cases have been reported in Wuhan or Hubei province, the original epicenter; and all new cases are imported from overseas (ie. no new domestically transmitted infections). China is already waking from its shutdown.
The Vietnamese seem to have succeeded in a similar manner, which was a necessity given their dense population and relatively poor medical system. They even wrote a special jingle for children about the need to wash their hands.
The South Koreans reacted very differently, by instituting a massive testing program. They did this because the main source of their infections was a secretive religious organization (responsible for more than 60% of the national infections), all of whom were compulsorily tested. This was expanded to include a large portion of the rest of the populace, as well (without any lockdown or other authoritarian measures).
The Iranian government, on the other hand, should all be charged with manslaughter. It seems that they officially hid the initial infections because of their potential affect on the turn-out at impending elections. They officially announced the presence of the virus on the same day as they reported the first death, which means that the virus had been circulating in the populace for weeks. Consequently, they are still reporting more deaths per day than almost anyone else.
As for Italy, a Nielsen survey early on reported that <20% of Italians were concerned about the virus and the possibility of a widespread epidemic. So, no-one did anything official until it was far too late. Studies have now clarified why they have had such a problem, and why Spain is now in such a similar situation. It appears to be family structure — the social importance of the extended family, as opposed to the nuclear family of two adults and two children, which is so prevalent elsewhere in the Western world since World War II. In the extended family, grandparents often regularly look after their grandchildren, especially if the parents commute to work. The grandchildren pick up the virus during the day, but do not develop obvious symptoms (they are in the healthy-lung non-risk group, remember). They do, however, bring the virus home to their family, who are not resistant, especially the grandparents.
This explains the disease infection rate, but not the death rate. The latter comes from the fact that Italy also has a large proportion of older people — 25% of the populace are >65 years old (for comparison, it is more like 16% in the USA). This has sadly been a lethal combination: an extended family structure and a large group of people at risk. Spain apparently has the same combination.
Japan is another country with a high proportion of elderly people (28% are >65 years), and has therefore been at great risk. However, they have stuck much closer to the nuclear family structure, as have the Chinese in recent decades. This seems to have helped limit the virus spread locally. Another important point is that older people do not often live alone (c. 10%), so that they do have family support coping with illness (compare with c. 25% in North America).
Germany and the Scandinavian countries have so far fared quite differently. They all have relatively high infection rates but so far quite low death rates. It seems that the infected people have generally not been in the high-risk groups. In the case of Germany, the health system also has more critical-care beds per capita than most other countries, which certainly helps. In the case of the Scandinavians, almost all of the initial infections came from people who went downhill-skiing in Austria and northern Italy, during the school break weeks. These people are likely to be younger, and relatively healthy. It remains to be seen how the situation changes as the virus spreads to other groups within these countries — at the moment, the critical-care patients in Sweden are mostly 50-70 years old, rather than >70.
Other countries have (very belatedly) imposed draconian social measures to limit viral spread, starting with the banning of large group meetings, then the closing of non-essential services — the USA is currently arguing about whether retail alcohol sales constitute essential services. In many places, there is now the banning of personal movement without a compelling reason. (Here in Sweden, limited movement is government advice, but not mandatory, so things seem relatively normal, although very quiet.)
This may be a useful strategy, but it is clear that many people do not understand it. You may have read that in Sydney (Australia) many of the people who had been told to stay away from work went to the beach, instead, because it was a sunny day. The sight of a crowded beach tells you just how little some people understand about a pandemic situation. Keeping 2 yard / meters apart gives everyone 40 sq.ft or 4 sq.m of disease-free space. Your governments are telling you to keep apart from each other, rather than barricade yourself in your home.
Sadly, this is also generating a backlash among some young people. Some of the people <25 years old have realized that most of them have natural resistance to the disease (healthy lungs), and so they are not concerned about getting the virus. They are now asking the obvious question: “why are we being quarantined, as well?” Once again, this question fails to distinguish the virus from the disease — not having the disease is different from not having the virus, which you can then spread it to others. We all know that the young will inherit the Earth, but the obvious answer to their question is: “because you don’t want to give the virus to your parents, and especially your grandparents, and thus inherit sooner rather than later.”
Some countries have had to start asking serious ethical questions. If the number of disease cases overwhelms the national medical system, then it becomes necessary to ask: “what order should people be medically treated, and for how long?”, and “whose lives should we try to save?” This assumes, of course, that the system can save lives from Covid-19 infection, which is not at all certain. A similar thing applies to the economy — lockdowns will drive many organizations bankrupt (particularly in the hospitality and tourism industries) but is intended to slow the virus spread. This assumes, of course, that the lockdown will be effective in the long term.
Possible strategies
The rate of disease spread is related to how many new people are infected by each currently infectious person. For the seasonal flu virus, this is c. 1.3 people, but for SARS-CoV-2 it seems to be higher, c. 2.8, denoting twice the exponential rate of spread. It is this number that it the key to why this has become a pandemic, whereas previous coronavirus outbreaks did not. The ease of infection spread is unprecedented for coronaviruses.
So, what containment strategies might work in the near future?
Closing national borders is unlikely to have as much effect as people might hope. It is far too late to keep the virus out, although it might help keep it in. There are too many exceptions to the closed borders (eg. nationals coming home, goods coming in) for complete containment. However, China is reporting that most of its new cases are among foreigners, not locals, so keeping them under control is not entirely useless.
The obvious downside is that shutting borders merely shuts the virus in, rather than keeping it out — it does not prevent spread within the closed borders. In China's case, the travel restrictions did not help Wuhan, where the virus originated, but did help the rest of the country. The upside is that it can slow the virus spread, so that the health-care facilities do not get overwhelmed — we actually need Covid-19 cases to appear slowly over time rather than all at once. That is, we do not actually want a big pandemic burst, to “get it over and done with”, because the health-care facilities cannot handle that scenario (as we can see in Italy).
In theory, closing schools is probably the single most effective thing that could be done, for families. This is not to protect the children, because they already have their own in-built healthy-lung resistance. Instead, it is to prevent them from picking up the virus from each other, and then bringing it home to their as-yet-uninfected family. Having sick parents is bad enough, but we don't need the kids to find out that they are the ones who made their parents sick in the first place. The practical consequences of closing schools, on the other hand, have been hotly debated, the biggest issue being that the people whose children are at home, instead of at school, may have to stay at home with them, including those who are running essential services (nurses, police, etc). As noted above, the grandparents should probably not fill the child-care role.
Working from home would be a good strategy for adults, if they can do it. This is obvious — you can’t get the virus from people you don’t meet. Try to keep away from public transport, for the same reason, along with live sporting and theatrical events, plus gambling dens. You might also prefer supermarkets where the staff wear gloves, and don’t insist on long queues at the checkout. These changes can lead to you to going stir crazy at home, of course, especially if you cannot get some dedicated personal space; and it can put a strain on your family life. There are now plenty of new online videos offering you advice on how to make it work. Have a wine tasting with your spouse, not an argument; play games with the kids, rather than yelling at them. Do not take up online poker — it is illegal throughout most of the USA.
The virus-testing of health-care professionals (of all sorts, including dentists) should probably be mandatory, and it already is in many places. These people are the ones most likely to get the virus, and also the ones whom we can least afford to have spreading it. Indeed, those people who work on infectious diseases seem to all understand that they will pick up something nasty, sometime in their professional lives. This happened, of course, with Li Wenliang, who was the first person to note the Covid-19 disease, last December, and who then died of it in February.
The common “medical” face masks that you sometimes will probably be useful if you are the one infected, and are trying to not spread the virus via your own respiratory droplets (in surgery, it is the medical staff who wear them, not the patients!). Otherwise, they do not necessarily prevent you from picking up something as small as a virus, even if you wear them properly (which most people don’t). An industrial dust mask will work, but they are too awkward and uncomfortable for long-term use.
Keeping the elderly away from younger people seems like a good idea, especially in aged-care facilities. Being with other older people may actually be okay, funnily enough, because they are the primary risk group, and if they have the virus then they will probably show symptoms, and you can then keep your distance. Sadly, since people are infectious but symptom-free when they first get the virus, you would be relying on the elderly showing symptoms fast (eg. 2 days not 7 days). However, Florida should consider closing its borders — this may actually be the single most effective thing the U.S. government could do for the elderly. Having children checking on retired parents, to see whether they are okay, may actually do more harm than good; use a Skype call, instead. The same thing applies to any sick people that you may know.
There is currently no officially recommended antiviral therapy for treating Covid-19. However, Remdesivir has been an effective pharmaceutical for other coronaviruses, and it is now being formally evaluated for Covid-19. This was originally developed for treating filoviruses, such as the Ebola virus, but it seems to be the best bet compared to all of the HIV and influenza drugs that have tested so far, although Lopinavir, Retonovir, Oseltamivir and Chlorphenamine have apparently also been recommended.
Being out in the open air away from other people will stop you from going stir-crazy, and might very well be safe. Indeed, if doing this is not okay, then we really are in the worst-case situation. A round of golf, during which you touch nothing but your own clubs and balls, and wash your hands when you get home, may do more good than harm for most people.
Hoarding toilet paper and dried beans is embarrassing, but it may indeed be necessary if your government bans you from putting your head outside your own front door. Whether you have health insurance or not does not matter in a national emergency — biology does not care about your social status, only your biological status. Everyone from government officials to Hollywood actors to international athletes to Formula 1 teams can get the virus, and have done.
Do not blame the Chinese, just because the virus happened to arise in Wuhan, in China. After all, the biggest pandemic in history, which killed more people than all of the military and civilian casualties of World War I and World War II combined, came out of the USA. The fact that history has called that disease The Spanish Flu does not hide the origin of the influenza virus in Haskell County, Kansas, in 1918. Viruses can arise anywhere at any time — people who live in glass houses should not throw stones.
Finally, do not panic, and do not prophecy Doomsday. Coronaviruses are usually not re-infectious — once you have produced your antibodies, you are likely to be safe. This has not yet been experimentally shown for the current pandemic, but early tests on the usual test organisms (macaque monkeys) have been positive.
Biologically, the only long-term safety is this form of immunization, which occurs when you are actually exposed to the virus. This leads to what is called “herd immunity”, in which most people are uninfected because they are now immune, so that those people who have not yet been infected are unlikely to encounter an infectious person — they remain safe, too. This is somewhat risky, of course, since it involves us all getting the virus at some stage. However, there is every reason to expect that a much safer immunization procedure will be forthcoming (although not for at least a year).
Great stuff. S/B mandatory reading for all. Thank you.
ReplyDeleteExcellent information. Thank you very much!
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