This is a trimmed down version of my last article with just the cites from the Imperial college paper to show that in the UK we are indeed using a simulated flu pandemic to guide UK policy and that it differs in almost every detail from the real disease. I know this is hard to understand or believe. But please check my cites carefully and you will see they do.
Before I go any further, if you are in the UK, be sure to protect yourself. This disease is not airborne (except for certain medical procedures). For details see my
First the background. You may not know that we in the UK are ignoring the WHO's advice. Allyson M Pollock, professor of public health at Newcastle university put it like this:
Case finding, contact tracing and testing, and strict quarantine are the classic tools in public health to control infectious diseases. WHO says they have been painstakingly adopted in China, with a high percentage of identified close contacts completing medical observation. In Singapore, Vietnam, and South Korea meticulous contact tracing combined with clinical observation plus testing were vital in containing the disease ....
The reasons why tracing was stopped, against WHO recommendations, have not been published. It seems to be connected to a shift from “contain” to “delay” in the government’s action plan, when contact tracing was replaced rather than supplemented with other control measures.
So - yes that is what happened, we moved from the contain to the delay phase. But why is the UK's "delay phase" policy so radically different from the WHO recommendations?
The reason is that the new policy is based on a simulated flu pandemic that ignores real world data. Most of the parameters are for flu, not for this novel coronavirus.
I am using their paper published on 16th March which is the very paper that publishes the UK policy and it's rationale.
Text: UK stands resolute on COVID-19 but policy comes from table for a SIMULATED flu pandemic with almost no input from not real world data
Read the paper itself and this is what it says:
We modified an individual-based simulation model developed to support pandemic influenza planning to explore scenarios for COVID-19 in GB. The basic structure of the model remains as previously published. Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand (16th March 2020)
The previous paper is: Strategies for mitigating an influenza pandemic [Imperial college model]
One third of transmission in household, one third in schools and workplaces, remaining third in the community.
With the parameterization above, approximately one third of transmission occurs in the household, one third in schools and workplaces and the remaining third in the community.
WHO: 78-85% of transmission in China was in households, and the secondary attack rate within families is only 3–10%, i.e. you have only a 10% or less chance of being infected by another contact in the same family.
In China, human-to-human transmission of the COVID-19 virus is largely occurring in families. … Among 344 clusters involving 1308 cases (out of a total 1836 cases reported) in Guangdong Province and Sichuan Province, most clusters (78%-85%) have occurred in families … preliminary studies ongoing in Guangdong estimate the secondary attack rate in households ranges from 3-10%. Report of the WHO-China Joint Mission
If you look at other data such as the data from Singapore, then contact tracing suppressed the outbreak, with almost no spread in the community.
Spread through schools
We predict that school and university closure will have an impact on the epidemic, under the assumption that children do transmit as much as adults, even if they rarely experience severe disease
Infections in schools were not a factor in Wuhan as the schools were closed for the Chinese New Year holiday, and the school holiday was extended during the lockdown. However they found no example of a child infecting an adult.
"The Joint Mission learned that infected children have largely been identified through contact tracing in households of adults.Of note,people interviewed by the Joint Mission Team could not recall episodes in which transmission occurred from a child to an adult." Report of the WHO-China Joint Mission
The Singapore schools and universities were not closed and they didn’t do a lockdown. They are are going to close schools now, from 8th April but they ramped all the way down from 1000 cases a day to below 100 a day without needing to do this.
This doesn't suggest that schools are driving the spread.
The WHO get asked about this from time to time in the press briefings and continue to say that the extent of transmission via schools is unknown. The Imperial College team's assumption that children do transmit as much as adults does not yet seem to have support from data.
AFAIK there have been no cases of major outbreaks started through schools or universities but many cases of large transmission clusters started in hospitals, care homes, prisons and of course cruise ships.
Doesn't model spread in hospitals, prisons or care homes
The WHO - China joint mission did however find that some of the spread prisons, hospitals and long-term living facilities.
"There have been reports of COVID-19 transmission in prisons (Hubei, Shandong, and Zhejiang, China), hospitals (as above) and in a long-term living facility. The close proximity and contact among people in these settings and the potential for environmental contamination are important factors, which could amplify transmission."
This has continued to be a significant driver, especially for new outbreaks. Outbreaks of COVID-19 have often started in health care systems
Dr Bruce Aylward talks about all this here:
If your health system goes down you can't run your response early days of Ebola in West Africa it was one of the big big challenges we had and it's a common thing when emerging disease nobody knows It enters through the healthcare system remember that's where a virus is going to enter often because they come in looking for care and and all of a sudden boom it blows up
...
Most healthcare workers got infected in the community not in the health care system.
This is not discussed in the paper
Asymptomatic spread
They assume a third of cases are sufficiently asymptomatic they won't know to self isolate
We assume that symptomatic individuals are 50% more infectious than asymptomatic individual
We therefore assume that two-thirds of cases are sufficiently symptomatic to self-isolate (if required by policy) within 1 day of symptom onset, and a mean delay from onset of symptoms to hospitalisation of 5 days.
In the WHO - China report however, asymptomatic spreading was rare and was not a major driver of the spread
Asymptomatic infection has been reported, but the majority of the relatively rare cases who are asymptomatic on the date of identification/report went on to develop disease. The proportion of truly asymptomatic infections is unclear but appears to be relatively rare and does not appear to be a major driver of transmission.
In Singapore, anyone with mild symptoms resembling COVID-19 who asks for treatment anywhere in Singapore has been automatically tested for COVID-19 since the 28th January. Most of the cases they find belong to known clusters or they are imported cases from other countries.
As of April 6th the WHO continue to see no evidence that asymptomatic transmission is driving the spread:
What we know from reports, what we know from published literature is that the predominant way in which transmission is occurring is amongst symptomatic individuals and these are people that can be very early on in symptoms, even when they start to feel a little bit unwell. This is supported by some data that attempts to catch a virus from individuals who are symptomatic.
We also know that it's possible that people can transmit in the few days before they become symptomatic or in their pre-symptomatic phase. There have been some studies that have come out and we learned about this when we were on mission in China back in January or early February, that there are individuals that can shed virus one to three days before they develop symptoms.
However it's very important to note that even if you are pre-symptomatic or even if you don't have any recognised symptoms you still have to transmit through droplets, you still have to have these infectious particles that come out of your nose and your mouth. So while we know that that is possible we do not believe that it's a major driver of transmission.
WHO Covid-19 transcript 6th April: Presymptomatic and asymptomatic spread
They do think it's possible that there are large amounts of unrecognized transmission, but this is likely not asymptomatic. They expect these to be mild cases that are missed by current surveillance strategies.
We've also seen modelling estimates that suggest that there're large numbers of unrecognised transmission and I used unrecognised on purpose because I'm not saying asymptomatic. I'm saying that we may be missing people who are out there who are infected but we're missing them because of current surveillance strategies. That is certainly possible in many parts of the globe.
WHO Covid-19 transcript 6th April: Presymptomatic and asymptomatic spread
Airborne transmission:
Transmission events occur through contacts made between susceptible and infectious individuals in either the household, workplace, school or randomly in the community, with the latter depending on spatial distance between contacts.
The latest advice of the WHO as of 29th March continues to be that airborne transmission has not been reported.
According to current evidence, COVID-19 virus is primarily transmitted between people through respiratory droplets and contact routes.
In an analysis of 75,465 COVID-19 cases in China, airborne transmission was not reported.
In the context of COVID-19, airborne transmission may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed …
See my
- The coronavirus COVID-19 is NOT AIRBORNE
Case isolation periods
This is where all this is turned into policy, based on their simulated flu pandemic
Text: UK stands resolute on COVID-19 but policy comes from table for a SIMULATED flu pandemic with almost no input from not real world data
[First two interventions]
Case isolation in the home
Symptomatic cases stay at home for 7 days, reducing non-household contacts by 75% for this period. Household contacts remain unchanged. Assume 70% of household comply with the policy.
Voluntary home quarantine
Following identification of a symptomatic case in the household, all household members remain at home for 14 days. Household contact rates double during this quarantine period, contacts in the community reduce by 75%. Assume 50% of household comply with the policy.
WHO recommend that mild cases found at home should be separated from the rest of the household in hospitals. If this is not possible because of the burden on the health system, then they can be separated in temporary wards in stadiums, community centers etc. If this also is not possible then they can isolate at home but this requires careful clinical judgement and assessment, and the patients and household members need to be educated on how to do it, and provided with on going support.
In cases in which care is to be provided at home, if and where feasible, a trained Health Care Worker should conduct an assessment to verify whether the residential setting is suitable for providing care; the Health Care Worker must assess whether the patient and the family are capable of adhering to the precautions that will be recommended as part of home care isolation (e.g., hand hygiene, respiratory hygiene, environmental cleaning, limitations on movement around or from the house) and can address safety concerns
The patient and carer both need to wear clinical masks and know how to use them. This is the one situation where the WHO say that members of the public should wear medical masks.
To contain respiratory secretions, a medical mask should be provided to the patient and worn as much as possible, and changed daily. Individuals who cannot tolerate a medical mask should use rigorous respiratory hygiene;
Caregivers should wear a medical mask that covers their mouth and nose when in the same room as the patient. Masks should not be touched or handled during use. If the mask gets wet or dirty from secretions, it must be replaced immediately with a new clean, dry mask.
As for isolation then the WHO recommend that isolation continues for as long as there are any symptoms (so, that’s including a cough of course) and for an additional 14 days after the symptoms resolve (i.e. until your cough and other symptoms completely disappear) or until there are two negative PCR tests 24 hours apart:
For mild laboratory confirmed patients who are cared for at home, to be released from home isolation, cases must test negative using PCR testing twice from samples collected at least 24 hours apart. Where testing is not possible, WHO recommends that confirmed patients remain isolated for an additional two weeks after symptoms resolve and monitoring should continue for the duration of home care.
WHO Director-General's opening remarks at the media briefing on COVID-19 - 16 March 2020Detailed advice here: Home care for patients with COVID-19 presenting with mild symptoms and management of their contacts
The UK isolation periods can’t be reconciled with real world data. SARS patients were infectious for up to three weeks, and the virus was detected up to a month after symptoms started.
For SARS coronavirus, viral RNA is detectable in the respiratory secretions and stools of some patients after onset of illness for more than 1 month, but live virus could not be detected by culture after week 3
Understanding COVID-19: what does viral RNA load really mean?
It is similar for COVID-19 - patients shed virus for a long time. Through to death for those that die. They shed virus for over a month for those that survive.
Duration of viral shedding ranged between 8 and 37 days. The median duration of viral shedding was 20·0 days (IQR 17·0–24·0) in survivors, but continued until death in fatal cases. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study
For more background and details, see my
Herd immunity assumption and mismatch with data from SARS
The Imperial college policy modeling is done on the basis of herd immunity as a central hypothesis.
Although the UK has said it is not the aim to develop herd immunity in the entire population, the working assumption behind their modeling is that the virus can be slowed down through developing sufficient immunity in the population to slow down its spread, combined with physical distancing. This is of course based on all the previous assumptions of a third of the infected population being asymptomatic spreaders as well as being immune and their assumptions about how it is transmitted.
On recovery from infection, individuals are assumed to be immune to re-infection in the short term. Evidence from the FluWatch cohort study suggests that re-infection with the same strain of seasonal circulating coronavirus is highly unlikely in the same or following season (Prof Andrew Hayward, personal communication).
This is the basis for their modeling of the effects of the interventions. Their model is that if you do nothing, then at the peak of infection in mid May, over 250 intensive care unit beds will be needed for every 100,000 in the population. The aim of the policies currently adopted is to reduce this to less than 100 intensive care units per 100,000 of population which still way overwhelms the current critical care unit capacity, which is why they are urgently building all these new hospitals; we need many times the current number of intensive care unit beds to treat them all.
The blue curve there is the result of applying all the current policies, but doesn’t include the effect of isolating everyone at home or some of the other major policies the UK has done in addition to the recommendations in this paper.
Herd immunity is central to this prediction and their strategy. They explain:
The aim of mitigation is to reduce the impact of an epidemic by flattening the curve, reducing peak incidence and overall deaths (Figure 2). Since the aim of mitigation is to minimise mortality, the interventions need to remain in place for as much of the epidemic period as possible. Introducing such interventions too early risks allowing transmission to return once they are lifted (if insufficient herd immunity has developed); it is therefore necessary to balance the timing of introduction with the scale of disruption imposed and the likely period over which the interventions can be maintained. In this scenario, interventions can limit transmission to the extent that little herd immunity is acquired –leading to the possibility that a second wave of infection is seen once interventions are lifted.
However this is a novel coronavirus and this is not known. Our experience of short term herd immunity for the four coronaviruses that have adapted to humans over thousands of years may not match what happens with the three novel coronaviruses that have recently leapt to humans.
What’s more SARS had a perverse reaction to reinfection. It had antibodies that could actually make the disease worse on reinfection like Dengue fever.
In rare cases dengue can be very serious and potentially life threatening. This is known as severe dengue or dengue haemorrhagic fever.
People who've had dengue before are thought to be most at risk of severe dengue if they become infected again. It's very rare for travellers to get it.
The belief is that low levels of antibodies cannot neutralize or kill the invading viruses. But they do bind to them and effectively usher them into susceptible cells, where the viruses then replicate.
Scientists solve a dengue mystery: Why second infection is worse than first - STAT
SARS is one of the very few viruses that have this immune system backfiring.
Since the 1960s, tests of vaccine candidates for diseases such as dengue, respiratory syncytial virus (RSV), and severe acute respiratory syndrome (SARS) have shown a paradoxical phenomenon: Some animals or people who received the vaccine and were later exposed to the virus developed more severe disease than those who had not been vaccinated (1). The vaccine-primed immune system, in certain cases, seemed to launch a shoddy response to the natural infection. “That is something we want to avoid,” says Kanta Subbarao, director of the World Health Organization Collaborating Centre for Reference and Research on Influenza in Melbourne, Australia.
This immune backfiring, or so-called immune enhancement, may manifest in different ways such as antibody-dependent enhancement (ADE), a process in which a virus leverages antibodies to aid infection; or cell-based enhancement, a category that includes allergic inflammation caused by Th2 immunopathology. In some cases, the enhancement processes might overlap. Scientific debate is underway as to which, if any, of these phenomena—for which exact mechanisms remain unclear—could be at play with the novel coronavirus and just how they might affect the success of vaccine candidates.
News Feature: Avoiding pitfalls in the pursuit of a COVID-19 vaccine
This has caused problems with vaccine development for SARS. An early candidate vaccine caused the immune system to attack the lungs, and this was solved by a new approach where only one spike from the SARS virus was used to trigger antibodies.
When SARS, also a coronavirus, appeared in China and spread globally nearly two decades ago, Hotez was among researchers who began investigating a potential vaccine. In early tests of his candidate, he witnessed how immune cells of vaccinated animals attacked lung tissue, in much the same way that the RSV vaccine had resulted in immune cells attacking kids’ lungs. “I thought, ‘Oh crap,’” he recalls, noting his initial fear that a safe vaccine may again not be possible.
But his team revised their approach. Instead of producing the whole spike protein of the virus, they built just a tiny piece of it—the piece that attaches to human cells, called the receptor-binding domain. Subsequent animal tests showed that this strategy did provide the desired protection without the unwanted immune enhancement. With funding from the NIH, Hotez’s team continued on to manufacture the vaccine and were ready for clinical trials.
News Feature: Avoiding pitfalls in the pursuit of a COVID-19 vaccine
So the “herd immunity” not only might not protect against reinfection.
There is a possibility that can’t yet be ruled out that the antibodies make reinfection more deadly.
Details here:
No sign of anyone doing anything improper here - but how do we move on?
In all this, there were no political motives as far as I can see. Boris Johnson followed the advice of his chief medical officer who was advised by the Scientific Advisory Group for Emergencies who in turn were influenced by the modelers. The modelers in turn were supremely confident in their model, as is often the case for modelers. They were all doing their best, and I see no sign of anyone doing anything improper here. It's more an issue with the framework or system than any individual. See UK Government is resolute about tackling COVID-19 in my previous article.
There doesn't seem any point in trying to assign blame. There may be things to examine later on about how this could happen, and to prevent it happening in the future, but for now the priority is, what do we do next?
If the real life disease had been the same as their simulated flu this might have been the only way to tackle it. And we'd get through it. But if the WHO are right, we can do so much better than that.
Whether it's succeeded in delaying things a bit or not, we still have to find a way out of our lockdown.
Exiting from a lockdown
The WHO say that once you raise a lock down you have to have an alternative method to suppress the infection, namely the test finding, case isolation, contact tracing etc.
Dr Mike Ryan put it like this:
Once you raise the lock-down you have to have an alternative method to suppress the infection. The way to do that is active case finding, testing, isolation of cases, tracking of contacts, quarantining of contacts and strong community education and participation and ownership around normal physical distancing, hygiene and giving communities the power to control infection by in effect managing their own physical distance, managing their own capacities to support the response.
In that situation, if you've strong public health capacity, if you've got a community that's mobilised and empowered and if you've strengthened your health system then you're potentially in a position to start unlocking or unwinding the lock-down.
COVID-19 virtual press conference -6 April, 2020
For more details see the rest of his reply at 00:34:29
Protecting yourself
The WHO who fight 200 epidemics a year run safe and they recommend these precautions and use them themselves to stay safe in China and in Wuhan for the big WHO-China report. WHO's Maria van Kerkhove, and Bruce Aylward who both did a 9 day study of China visiting the worst hot spots in Wuhan followed these precautions and didn't get it.
You can stop it by thorough hand washing before you touch your eyes nose or mouth and by keeping a physical distance of 1–2 meters from anyone talking, sneezing or coughing. This is not so effective for flu or some colds as they are airborne. However this method is very effective for COVID-19. This protects you and also protects others who could otherwise be infected through you in a transmission chain. You need to practice these things until they become an automatic sequence like tying your shoelaces or brushing your teeth. This is how Bruce Aylward put it when interviewed by W5 in Canada:
This is a respiratory disease at the end of the day which means it can move very easily from me too you well not right now cuz you're too far away [1 meter away]
If your population knows how to protect itself you're gonna be very successful with this disease.
If I'm washing my hands, if I'm [doing] proper respiratory hygiene avoiding the others social distancing and know what to look for not just in myself but in others I'm going to be safe, or quite safe. There's no such thing as zero risk but you can really reduce the risk. I spent two weeks nearly three weeks in the epicenter of the biggest outbreak in history. I'm fine.
For details see my
Proposal for urgent data driven public examination of scientific evidence base
In my previous article I proposed an urgent data driven public examination of the scientific evidence base to understand why our policy is so different from the WHO and try to establish what our priorities are now during the lockdown. See Public evidence based science debate on basis of UK policy
My longer article is here, and perhaps after reading this you may be interested in more details:
If I have made any mistakes in any of this please don't hesitate to say.
Comments