The Pandemic Initial document prepared May 14th. Some minor updates added June 23rd 2020. It seems obvious that the virus cannot be eliminated in the world population until effective vaccines are developed - its propagation must be managed to allow a controlled spread of the virus whilst allowing economies to function. To put the virus into context, the death rate in Europe will be about 20% more than the last severe flu season (2017/18). Initial responses to the spread of the virus have used periods of social distancing and stay at home orders to reduce case and death rates especially amongst the at risk older population and to avoid overwhelming the hospital and healthcare systems. In Washington, the Governor’s action and the response of Washingtonians have diminished cases and most importantly the hospitalization and death rates. These rates have reduced greatly in May and June and have not followed the dire estimates from some models and emergency hospitals were not needed. Indeed, the use of masks, hand washing and social distancing may be allowing more asymptomatic/low illness severity spread of the virus. It has also been encouraging to see no spikes in cases following recent street protests. Indeed, it is becoming clear that we have to focus on hospitalization and death rates, not just case rates. In Washington State, the normal average daily death rate is about 150 persons per day. The current COVID-19 death rate of 5 to 10 persons per day is a small perturbation on that number (see chart in Reference 1). At the peak of the outbreak in Washington the COVID-19 death rate was ~40 per day and we may still see short-term fluctuations or statistical corrections that might approach that level on top of a falling rate. The death rate is now at the level where other effects of the stay at home policy, such as fear of seeking medical attention, may add or subtract from the death rate. For instance, the reduction of traffic may reduce traffic related deaths, fear of may increase the suicide rate and deaths from drug overdose may increase, and untreated heart attacks and reduced rates of cancer diagnosis and childhood vaccination may cause longer term rises in illness and morbidity. As the economy reopens, continued use of age appropriate social distancing, face masks, frequent hand washing, temperature measurement combined with testing, contact tracing and self-isolation of those testing positive will be needed to control outbreaks as we are likely far from herd immunity. These measures may also help reduce the viral load that occurs in an inadvertent infection. The viral load experienced in an infection seems to be important in determining the severity of the disease (see the German epidemiological study by Prof Hendrick Streeck in Reference 2). The infection with low doses of virus may also be allowing symptom-free spread of the virus. Hence, the important parameters to monitor in testing and contact tracing may not be just the number of infections in an outbreak but also take into consideration the number of hospitalizations associated with an outbreak. Even as the economy opens up, it will remain important throughout to isolate the elderly and those adults with underlying health conditions known to increase hospitalizations and mortality. To open the economy requires switching to a more local control of outbreaks via testing and contact tracing. This seems to have been successfully used by other countries to confine outbreaks, whilst allowing significant economic activity. Additionally, the development and use of antiviral drugs (e.g. Gilead Science’s drugs Remdesivir) and some steroids would help reduce the time patients with COVID19 stay in the hospital and death rates and hence reduce pressure on health care systems. The psychological effects of the pandemic can also not be underestimated, with some forecasts predicting an extra 70 thousand addition suicides in 2020 due to fears of the pandemic, the economic fall out and the stress of being confined at home. – see https://www.ecowatch.com/coronavirus-mental-health-drugs-suicide- 2645952573.html?rebelltitem=5#rebelltitem5 https://www.statnews.com/2020/04/30/suicides-two-health-care-workers-hint-at-covid-19-mental- health-crisis-to-come/ (in case hyperlinks fail to open, please copy and paste links into your web browser) https://www.sciencemag.org/news/2020/06/cheap-steroid-first-drug-shown-reduce-death-covid- 19-patients Despite the fact that in the US we are still close to the peak of infections with rates still upwards of 20,000 per day and recently risen to 30,000 per day as a few states reopened before going through a peak, the overall hospitalization and death rates from the virus are still falling – see Reference 3 for a copy of page 13 of the weekly updated CDC report that shows the mortality rate for pneumonia, COVID-19 and influenza for May 2nd reported on May 14th – see also the Covibes or Worldometer data for June 23rd. This graph may indicate a seasonality to the spread of the virus, or some mutation in the virus to a less severe illness, or a reduction of the number of possible cases due to natural or acquired immunity from infections by other types of corona viruses of a portion of the population and to symptom-free spread of the disease or a combination of these, perhaps, with other unknown factors. The numbers of people who are naturally immune and the numbers of symptom- free infections remains unknown though the data from the Diamond Princess indicates that only about 25% or so of the population are vulnerable. To obtain these vital numbers will require reliable tests for antibodies from randomly chosen samples of a population. Knowing these important numbers will allow close estimation of how many people will need to be infected to achieve some level of herd immunity/reduced illness response to the virus if they are re-infected. In predicting the number of cases in an outbreak, there are many models being used that have had varying success (some greatly overestimating cases and deaths) in predicting the course of the outbreak. Models must estimate many parameters imprecisely and are difficult to get right. However, there seems to be an almost universal epidemiological curve that can be fitted to any outbreak, even when different forms of social distancing are in place, as long as the methodology of measuring an outbreak remains consistent during the outbreak. See Reference 4 for a link and reproduction of some of the curves for the US from the CoVibes web site created by Dr Patrick Tam. We think this will be useful to decision makers. For instance, the curves for the US predict a total of about 125 to 150 thousand deaths as the epidemic recedes - more details in Reference 4 below. Children and COIVD-19 We are fortunate indeed that children are the least at risk from this highly contagious disease. The Swiss research strongly suggests that children under 10 are not easily infected and may have low numbers of receptors for the virus (Reference 5) and are allowing brief contact between grandparents and children. Additional, very detailed research in Iceland (Reference 6) that can detect the direction of infection, shows that adults can infect children but it is extremely rare for children to infect adults. Other countries are opening up their schools or, like Sweden, never closed their schools for under 16’s. As cases are falling in Sweden it seems like the mingling of children at school is not resulting in a huge spread of the disease amongst staff and parents. In our own state, childcare has been open since the stay at home order – due to the fear at the time of overwhelming the health cares system, the Governor needed to keep essential workers attending their jobs in the healthcare system and other essential systems such as communications and the internet, software. Thus childcare was kept open even though the risk to children was low but it was unknown whether they would be silent super- spreaders. The risk taken has paid off. With all the reasonable and suitable precautions in place, childcare centers do not seem to be associated with outbreaks in childcare workers and families. Indeed, with younger children it is hardly possible to maintain social distancing suggesting that class sizes may be more flexibly sized in the future than initially thought. All this suggests that schools, especially those for ages 12 and under, are at low risk for COIVD-19 illness amongst staff and pupils, and are not significant sources of spread of the corona virus, whether the virus activity is low or high in the rest of the population. The key to safety at schools would seem to lie with keeping adults observing appropriate distancing. Thus, keeping staff in small groups with masks and social distancing and preventing parents from mingling with staff and each other would be most important. A recent article in the Lancet, concludes that school closings do little to reduce COVID-19 deaths compared with other social distancing measures - see Reference 7. Here is a quote from one of the authors of the scientific article:- “Data on the effects of school closures on COVID-19 are limited as the pandemic is still under way, but researchers at University College London said evidence from flu epidemics and outbreaks caused by other coronaviruses suggests their impact on the spread of the disease will be small. “We know from previous studies that school closures are likely to have the greatest effect if the virus has low transmissibility and attack rates are higher in children.