Anyone who has read even briefly into written human history is going to be aware that it is as much defined by our epidemics and pandemics as by any of our technical and societal achievements. This post is essentially a quick range over the history of pandemics and epidemics with links and some focus on COVID-19.
The effects of pandemics is apparent in the written accounts of the Plague of Justinian which winnowed the Eurasia and Africa for from the 6th century and variations repeating to the early 20th century Or the undocumented plagues that repeatedly decimated or destroyed civilisations in the Americas prior to European invasions. Or the plague disasters that followed the colonial empires spreading regional diseases on a grand scale keep reverberating in indigenous populations to the present day.
Most of the diseases that have been common through human history have had their impacts constrained with the awareness of the sources of epidemic diseases, the introduction of better sanitation, the long slow history of developing vaccines, and effective preventative medical treatments.
But through the 20th century, at least in developed world, the ever-present dread and awareness of epidemics that was still residual during my childhood in the 1960s has dissipated. My grandparents lived in aftermath of the 1918 influenza pandemic. My parents grew up as the polio epidemic was attacking their classmates. During my childhood there were continuous mini-epidemics of various infectious diseases from mumps to measles.
Our generations saw the effect of the introductions of vaccines and the loss of knowledge about epidemics in our society diminished.
As an example in my life, diphtheria was a disease that well known to my grandparents and parents. But it was disease that I had no idea about. The vaccine was introduced into NZ in 1941 for children under 7 well after the 1921 epidemic. This graph from a 2016 post by Helen Petousis-Harris at Te Pūnaha Matatini “If only there had been a vaccine” displays clearly why I wasn’t aware of it – I was born in 1959.
When I’ve talked to my younger relatives and colleagues, their ignorance of the dangers of diseases that were worried the hell out of my parents when I was growing up is just scary as hell. They simply don’t feel the fragility of the clean water systems that we depend on to stave of outbreaks of diseases like cholera, or why using antibiotics blithely for viral diseases or milk production is a stupid idea, or why using vaccines isn’t an individual choice like what brand of cellphone you like.
This ignorance has been particularly apparent to anyone who has spent time online looking aghast at the deliberate spreading of misinformation by anti-vaxxers over the last decade. Instead of the ever-present dangers of re-emerging diseases, recent generations seem to be more invested in the fantasies of the zombie apocalypse rather than the more mundane concerns about rubella or measles.
Virtually all of the epidemics that have a potential of flaring into pandemics now appear to be emerging infectious diseases especially those noted as being ‘novel’ or previously unknown to our medical histories.
Emerging infectious diseases are infections that have recently appeared within a population or those whose incidence or geographic range is rapidly increasing or threatens to increase in the near future. Emerging infections can be caused by:
- Previously undetected or unknown infectious agents
- Known agents that have spread to new geographic locations or new populations
- Previously known agents whose role in specific diseases has previously gone unrecognized.
- Re-emergence of agents whose incidence of disease had significantly declined in the past, but whose incidence of disease has reappeared. This class of diseases is known as re-emerging infectious diseases.
The World Health Organization warned in its 2007 report that infectious diseases are emerging at a rate that has not been seen before. Since the 1970s, about 40 infectious diseases have been discovered, including SARS, MERS, Ebola, chikungunya, avian flu, swine flu and, most recently, Zika.
With people traveling much more frequently and far greater distances than in the past, living in more densely populated areas, and coming into closer contact with wild animals, the potential for emerging infectious diseases to spread rapidly and cause global epidemics is a major concern.
To that list, we can now add severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the virus strain that causes COVID-19. This is probably a well established viral disease in bat populations that has recently made the jump to humans via an immediate species.
Inter-species crossover has been a common theme in novel infectious diseases. HIV probably crossed over from chimpanzees in the early 20th century. MERS is probably a crossover from camels. Ebola probably also from bats via infected apes. Avian flus mostly from from birds and swine flu mostly from pigs as their names indicate.
The issue with novel diseases is that when they do managed to have an inter-species crossover that allows for a successful intra-species infection in humans, they are sometimes extremely infectious. Frequently they’re so infectious that they are self-limiting.
Ebola is like this. When it gets into a susceptible population with poor medical support with social hygiene and customs that facilitate immediate transmission, the outbreaks burn themselves out fast. That is because the association between caring for patients or grieving for the dead becomes obvious within a short period to survivors.
This is a self-limiting strategy for the disease. To date Ebola has had limited success infecting anyone outside of central Africa despite a number of infected travellers, particularly in 2014.
The 2003 SARS outbreak was contained primarily because the number of people with mild symptoms were low. It also did not have a . This made isolation of the infected, the containment and testing of people that were associated with, and the eventual eradication of the disease feasible. But there was also a healthy dose of just luck as a World Health Organisation after-action-review made clear:-
The rapid containment of SARS is a success in public health, but also a warning. It is proof of the power of international collaboration supported at the highest political level. It is also proof of the effectiveness of GOARN in detecting and responding to emerging infections of international public health importance. At the same time, containment of SARS was aided by good fortune. The most severely affected areas in the SARS outbreak had well-developed health care systems. Had SARS established a foothold in countries where health systems are less well developed cases might still be occurring, with global containment much more difficult, if not impossible.
Although control measures were effective, they were extremely disruptive and consumed enormous resources — resources that might not have been sustainable over time. If SARS reoccurs during an influenza season, health systems worldwide will be put under extreme pressure as they seek to isolate all those who fit the clinical case definition until diagnosis can be ascertained. Continued vigilance is vital.
This chapter has illustrated how quickly a new disease can threaten global health. Thankfully, not all diseases move at such speed; but some are more stealthy and more lethal.
The SARS epidemic was contained within 12 months. Which in retrospect was somewhat unfortunate. Most of the advanced efforts to get an effective vaccine or treatment against SARS were shelved as the epidemic was being contained or in the decade following in a classic case of failing to be actively proactive after a scare.
There are a number of vaccines that were developed. Many of which had issues with the effect of the vaccine causing over-energetic responses in test subject’s auto-immune systems and increased symptoms. Unfortunately excessive auto-immune responses are also the main cause of fatalities with both SARS and COVID-19.
The COVID-19 is in many ways similar with the 2003 SARS outbreak as this Lancet article “Can we contain the COVID-19 outbreak with the same measures as for SARS?” but has some differences that make it far more stealthy.
Clear differences are emerging, such as in transmissibility and severity pyramids; COVID-19 has a higher transmissibility than SARS, and many more patients with COVID-19 rather than SARS have mild symptoms that contribute to spread because these patients are often missed and not isolated.
Mild symptoms with COVID-19 are really really problematic for containment because of the viral shedding as this quotation from the Lancet article makes clear (my italics).
Isolation was effective for SARS because peak viral shedding occurred after patients were already quite ill with respiratory symptoms and could be easily identified. Although asymptomatic or mildly symptomatic patients have been reported for SARS,35 no known transmission occurred from these patients. By contrast, preliminary evidence from exported COVID-19 cases suggest that transmission during the early phase of illness also seems to contribute to overall transmission;36, 37 therefore, isolation of more severely ill patients at the time of presentation to health-care facilities will be too late. The effectiveness of isolation and contact tracing methods depends on the proportion of transmission that occurs before symptom onset. Pre-symptomatic transmission will also make temperature screening less effective.38
In other words, with COVID-19 you can be infected with few or even no symptoms and still infect others as a carrier. With SARS it could be contained because people who had it were symptomatic and infectious or non-symptomatic and apparently not infectious. What is also known is that people who have gotten over the disease can also shed viruses for some time afterwards. The European CDC says in their discharge criteria
SARS-CoV-2 virus can initially be detected 1–2 days prior to symptom onset in upper respiratory tract samples; the virus can persist for 7–12 days in moderate cases and up to 2 weeks in severe cases (WHO mission to China Report) . In faeces, viral RNA has been detected in up to 30% of patients from day 5 after onset and up to 4 to 5 weeks in moderate cases. The significance of faecal viral shedding for transmission still has to be clarified .
In the absence of a vaccine or preventative treatment, the mild symptomatic infection and potentially long shedding periods mean in most places containment is likely to fail as strategy.
If we know someone has had the virus, they can potentially leave their home without risk of being re-infected, which would help countries get moving again. However, the accuracy of the tests has yet to be established. “The one thing that’s worse than no test is an inaccurate test,” Chris Whitty, the UK’s chief medical adviser, said on 25 March. Someone wrongly told they have already had covid-19 could go out and get infected.
The antibody response to the coronavirus may be delayed compared with other infections. The tests can be used only 14 days or more after people develop symptoms, says Adams.
This also means antibody testing will be of limited use for tracing the contacts of infected people – which many think is crucial for controlling the outbreak – because health authorities will be weeks behind.
Plus a positive antibody test doesn’t indicate where people are in the virus shedding cycle. Currently only a swab test taken by trained personnel and sent to lab for analysis will do that.
Which makes Boris Johnson’s enthusiasm for the antibody test (even assuming it works as advertised) as being ‘game-changer’ ridiculous. It serves more as an indication of his habit of being a dangerously ignorant idiot. The New Scientist article ends with a better informed and thought through analysis..
On the plus side, many groups are working on faster genetic tests and on antigen tests that can detect the virus in, say, saliva. Testing widely for both active infections and past infections should be a highly effective combination.
Of course to make that work for getting people back into the workforce, we’d probably need to bulk-order bracelets to allow confirmation for people who can be out and about because they neither get nor infect with the virus. I’d imagine that in NZ that being required to carry infection status identity will, in itself, cause some debate.
However in New Zealand we have what Jacinda Ardern describes as a “reasonable” chance of doing a containment strategy. Closed borders apart from those kiwis and their spouses and dependents still able to make it back, a slowly increasingly strict isolation policy for arrivals, and a lock-down for 4 weeks make it possible.
My background as a part-time army medic and as a lifelong student of the history of epidemics makes me want to get somewhat draconian.
For travellers arriving, our continuing primary disease vector, we should use the isolation model that Taiwan has been using. Ensure that people in isolation have food delivered and don’t have to leave. If they are in a hotel or home then require active tracking the GPS of phones, and regularly and randomly auto-poll that phone to make sure that the owner is next to the phone. One article I read on Medium which I can’t find now described the wakeup call that one taiwanese arrival got when their cellphone battery ran out of power and they had police banging on their door shortly afterwards.
If people don’t follow the common sense rules for isolation to prevent the spread of infection, then I’m sure that we can find an island and a tent to drop them on for a month until the court has time to deal with them. At the very least it will prevent them to be being a stupid danger to others.
I’d suggest that the same happens to the owner or manager of businesses who self-deem themselves to be ‘essential’. Not only are they putting customers in danger, but presumably they’re also pressuring employees to do it as well.
The biggest problems for NZ with our current strategy is to prevent issues with community transfer during and after the release of the lockdown. This would result in lockdowns extending or resuming in areas – often far wider than local areas.
So far I’m not optimistic that a single national lockdown will be completely effective because people seem to be taking some very liberal interpretations of what a household ‘bubble’ means. There are anecdotal reports of household bubbles joining up so that their kids can play together. Or kids playing games in parks. Its going to be interesting see how this plays out in the coming weeks. Each of these effectively widen out any lockdown to quarantine outbreaks.
Hopefully someone has started to do location tracking on cellphones to find out what are actual ‘local’ areas as evidenced by actual aggregate movements.
If our containment strategy does work and community spread is eliminated. Then the big question is – how we reconnect to rest of the world?
We’d wind up with a small number of immune people and most people being susceptible. At the very least, we’d need to have border antibody and live virus tests before people boarded and a rapid retest on arrival. Validation of the error rates on combinations of tests will determine the risk levels. Otherwise tourists, business travel, and returning kiwis will require 14 days quarantine.
Our tourist industry will be hanging out for a vaccine in NZ. Realistically before we can start up Hobbiton we’d require a largely immune population.
As importantly, before we restart our tourism industry or to allow kiwis to fly offshore again, we’re going to need to have a very close look at how we deal with the next ‘novel’ disease. I, for one, have absolutely no real interest in dying for tourism.
Basically we are trying to do with our containment strategies is to avoid the modern analogue in a covid-19 Italy and elsewhere of “bring out your dead”. This was the defining civic characteristic of past pandemics.
In Italy, as the fatalities of covid-19 overwhelm the funeral systems we get the military being called in to transport the dead.
At least it is a bit more civilised and dignified than the black humour of Monty Python’s depiction of the same task in a medieval plague.
Anything is better than that.