Controlling SARS-CoV-2

Controlling SARS-CoV-2

Thoughts on Controlling the Spread of Sars-CoV-2

This chapter extends and Public Advices and Suggestions chapter.

Summarized Transmission to Design Measures

The design of measures relies on transmission models. The dangerous transmission of Sars-CoV-2 is airborne in dry air. A metaphor is to think of the transmission as smoke-like and those heavily infected release a lot of smokes.

Indoor Transmission

Observations: The spread pattern shows that the cases of severe SARS-2 lung infections are high when a lot of dry air is exchanged between people which is the case in badly ventilated indoor rooms either heated (cold climates e.g. winters in Europe) or air-conditioned (very warm/sultry climates e.g. observed in Southern US in summer or regions of Brazil year round).

Explanations: In the air circulates around one breaths each others air. When heating, air-conditioning or the outdoor air is dry, the indoor air is dry. In dry air, tiny aerosol form. Tiny and dry particulates are most likely to be deposited in the deep lungs (chapter Airborne Transmission). The viability of coronaviruses is also highest in dry particulates.

Outdoor Transmission

Observations: On the other hand outdoors during the day, even in many crowded settings around the world (sometimes with masks, sometimes without), no increased spread has been observed (->Spread Analyses). Explanations: Outdoors the viruses get diluted and then either are cleared or decay. Due to decay and clearance there’s no accumulation (->Outdoor is Safer). Outdoors, the main transmission opportunity is droplet transmission in face-to-face situations. Droplet infections are unlikely to cause deep lung infections and therefore severe Covid is less likely (-> Disease Pattering.

Seasonality of Transmission

The spread in dry indoor air of coronaviruses (in fact most respiratory viruses) makes the spread seasonal:

In moderate climate zones, prevention measures (doing Sauna, pay attention to ventilation, vaccinate risk groups) are important in the winter, can be relaxed during the spring, in the summer the risk is low and in autumn care needs to be taken.

I don’t except strict measures to be necessary during Winter 2021 (-> Looking Ahead).

Spread Metaphor

Aerosol transmission behaves smoke like.

Droplet transmissions are micro spites and only happens when spitting into each others mouth is possible (droplet transmission is not important for the transmission of severe Covid). For droplet prevention distancing or plexiglas are enough.

Differences between Individuals

Summed Up

A short summary of recommended measure packages to reduce the Covid.

in work 22.8.

Overall the recommended packages is subjective. While measures to reduce Covid transmissions can be statistically analysed to some extent, the weighting of the society costs is subjective.

Year Round Measures

To prevent high rates of hospitalizations, some base measures can be adequate in risk regions.

Base Measures

Optional Measures

Summer Measures

Winter Measures

Mindset and Strategy to Tackle Covid

Mind set followed here to tackle SARS-CoV-2:

  • communication and explanation
  • knowledge & research
  • self responsibility, independent decisions combined with a circumspect lifestyle
  • Focus on overall life quality. This includes keeping overall health effects in mind: comparing different risks and the number of diseases and deaths caused, long-term damage, life quality cost (which can include economic costs).

Strategy

  • Measures preserving life quality and health of everybody.
  • Keep the spread controllable and react if necessary. E.g. limiting super-spreader situation since they can yield sudden and hard to control explosion in cases.
  • Monitor and estimate overall cases to do predictions and planning.
  • Settings that those who want/need can protect, while those not needing/choosing can go on, go on circumspectly.
  • Avoiding hospital overwhelming. Since it is hard for all the affected: the relatives, the medical staff and the patients. At times when shops, restaurants and bars are open and crowded, risking with a high probability or considering not to admit elderly to hospitals I think is not nice. Everybody has to right for a good treatment.

Reconsidering Strategy, Autumn 2020

In cold areas/times rules need to be tighter, since aerosol transmission is hard to (self-)prevent at least if good masks are scarce. In warm areas windows should be open all the time and air-conditioning should never be used.

Three more points

  1. Trying new paths but step by step and at the risk of falling having a parachute ready and using it early enough. Better walk with the parachute (and being ready for a new journey) than fall cool without. For Covid-19 the parachutes are outdoor days: being outdoors and avoiding all non essential entries to foreign or public indoor settings.
  2. Doing experiments in limited/small settings.
  3. Analyzing missteps can be rewarding, the next antibiotics are to be discovered.

Risk Management

Balancing of Measures

Here the goal is to minimize overall adverse health effects but not a zero-Covid. This includes unhealthy lifestyles motivated by overly strict measures or putting children at risk through vaccination and the unknown long term effects. However a very important goal is the avoid hospital overwhelming.

Regarding overall health, I my opinion, many countries should take measures towards clean air. It causes so many years of life lost and is nearly impossible to self prevent. Many countries have unhealthy levels of air pollution. There are countries - mainly in the Americas and in Africa - that do quite well.

In regions with high air pollution the are more severe Covid cases (Air Pollution in Spread Analyses).

The stringency of measures if given by the following table (Full Stringency Table for all infection rates on the Monitoring Page)

C-Deaths/Million/day Stringency
~.5 if less or not increasing: loose rules, self responsibility
~1 if greater and increasing: Prefer outdoors to indoors, monitoring needed.
~2.5 worrisome if greater and case count increases => tighten the rules, infection risk is increased due to many infected.

C-Deaths/Million/day = number of Covid-19 deaths per million inhabitants per day.

On Balancing of Measures

written in May to July 2020, updates to be done

Hospital Overwhelming

Reasons to avoid hospital overwhelming (with good planning some of the reasons can be overcome):

Individual Protection Measures

Support Immune Protection

Completely avoiding Sars-CoV-2 can be as hard as avoiding dust and smoke. This is hard. Even in laboratory settings virus protection is difficult [Wurtz, Raoult et al, Artika and Ma’roef] and Sars-CoV-1/2 protection is difficult. There have been several cases of infections in labs with Sars-CoV-1 Orellana et al, Lim et al and recommendations for autopsies of Covid-19 fatalities are very strict Finegan et al. Out of labs, once a coronavirus is widespread, complete avoidance is nearly impossible. Sars-Cov-2 is widespread. The best protection available is a good immune system. Vaccines - if once available available in 2021 - just prepare the immune system and do not replace it. So the long-term focus should be to support the overall health of humanity. In tropical regions where Sars-CoV-2 infects less virulent but there are many more infectious diseases overall health should be the main focus - alongside always open windows and no air-conditioners if there are Covid-19 cases.

Proposals for good health:

There are many more good reasons good health - including an intact immune system - is important.

Masks

Mask reduce spread since they mitigate both the infection and spread risk. Masks should be changed frequently but can be reused. To prevent droplet transmission outdoors or in very well ventilated situations any mask helps. To prevent aerosol transmission indoors a good filtration and clean mask is necessary. The filtration of most surgical masks is ok. FFP masks or analog have good to very good filters. A good and dense fit is important, especially for masks with a high filtration. More on the page Masks.

Ventilation

Ventilation reduces the indoor airborne spread, since the virion density in outdoor air is much lower than in indoor air. In sensible locations limits on the CO2 concentration and continuous monitoring ensure good ventilation (the indoor CO2 concentration is e.g. described in Stocker).

Distancing

Airborne transmission - both droplets (reek of alcohol like spread) and aerosol/dry particulates (smoke-like) - can be reduced with distancing. Outdoors or with good ventilation, less distance is required. So if inside 2 meters is good, outdoors likely half a meter is enough. Wind direction is relevant outdoors. Inside, the airflow can have a direction too: e.g. the kitchen hood and the toilet venting draw air.

Large Buildings

Large residential block and office buildings special care needs to be taken, since the transmission risk is increased:

Suggested precaution measures:

Covid-19 Cases and Quarantine

The focus should be on monitoring cases both for disease progression and to figure out and break chains of severe infections.

The strict isolation rules were designed with SARS-1 and it’s prevalence in mind: a few sporadic and severely sick cases. Additionally a droplet and fomites transmission model was assumed, which makes isolation in an indoor room effective. However regarding the aerosol transmission indoor isolation can backfire unless one lives in a single person house.

In my opinion, especially in the case of targeted testing, those living in flats with small living spaces, which already have a greater infection risk, should not have additional penalties, which possibly hinder a healthy recovery and put fellow occupants at risk.

Relaxed rules are important for the health of the infected and the possibly infected and in many situations relaxed rules are more efficient in reducing the spread.

Example Calculation of Spread

Overall in the above scenario the relaxed instruction yield an overall lower spread since more people do testing/are transparent about symptoms.

Suggestions for possibly Infected

Suggestions for Infected

as for Possibly Infected and additionally:

Isolation by Home-Lockdown

To reduce spread isolation by home-lockdown is a radical measure. The more is known about Sars-CoV-2 and its spreading the more fine-grained the measures can be.

Isolation by a stay-at-home-order may be working for people with own houses with gardens but for people living in flats in big buildings (and the majority of people do so in Covid risk regions), permanent home stay can increase transmission opportunities and has adverse health effects since movement is healthy.

General Public Measures

Contact Tracing

to be written

Testing Benefits

To be redone (23.8.21). I opted here back in 2020 for benefit associated testing, it is widespread now in 2021. However not in the sense this was once intended and written back in November 2020:

  • The idea was to have easy accessible tests without ‘punishment’ upon a positive test result and motivation to take tests in sensible situations and not required testing for day-to-day life.

    In Switzerland antigen test are free to obtain in pharmacies (limited number per month) (not any more as of November 21). I consider this a good solution in sensible situations one can do a morning before breakfast test and if both are negative, changes are low for a Covid infection (Covid Diagnosis).

  • In November 2020 the situation was different than now in than in August/November 2021: Suitable immunisation options for risk groups are available and promising treatments options are known, e.g. interferons. Topical methods such as steam inhalation may also be beneficial as proposed in a brainstorming chapter on Topical Treatments.

Often turning up for test is not associated with any benefits, on the contrary if tested positive for Covid in many countries a home isolation rules apply and one needs to disclose contacts and possibly movement history. A different approach is whitelist testing e.g. those who test negative get benefits.

Outdoor Days

Avoiding foreign and public indoor rooms. Prevents aerosol transmission if care is taken in essential buildings (e.g. shops and residential blocks) and public transport. To prevent (the likely less relevant) droplet transmission, masks can be used for face to face talking outdoors. outdoor transmission does rarely cause severe Covid

Home-Lock Down

A general curfew is a radical measure. It reduces contacts and makes it easier to enforce a ban on entering foreign indoor rooms. This measure was mainly used in Winter/Spring 2020 when the information about SARS-CoV-2 was limited and transmission unclear. It has very severe drawbacks compared to outdoor days:

A curfew at night is less radical and was sometimes used e.g. to prevent private parties but in nearly all situations softer measures are more adequate e.g. Reduction of Nightlife.

Temporary Financial Support

written in autumn 2020, as of September 2021 I think closures are hardly ever adequate or necessary.

Some businesses will mainly be closed to break waves (e.g. gastronomy) while other businesses likely are reduced for the foreseeable future such as long distance traveling or large scale events. For the first temporary support helps for the latter enabling better switching of business models is an option. Also some temporarily closed businesses, especially if closed for a longer time period, may not be able to return to the business model e.g. the customer behavior can change.

As noted restrictions are dependent on the local situation and on the weighting/prioritizing of the benefits and costs, so Covid measures vary a lot between different regions.

General Support

Additional to temporary support, general support and enabling for those who need or want to reorganize is adequate. How to take the corona-situation as an opportunity to reform the economical systems on the economics page.

Specific Public Measures

(in work and currently more brainstorming)

This sections discusses measures that can be put in place if Covid-19 increase rapidly. For each measure

Corona Conform Skiing

Summary Corona Conform Skiing

Nowadays (pre-corona) practiced cosy warm (après-)skiing is unsafe. The more outdoor the skiing-experience (including queuing & lifts & gastronomy) is the safer. Good ventilation can make the ski experience more outdoors like. Lowering the maximum crowd density is helps too, especially indoors.

My memories of skiing date back to the early 90s, back then a ski day was mostly outdoors from open-sky lifts to outdoor lunch.

Allowing skiing in some regions first, I consider beneficial, since all can benefit from the experiences gathered. Ideally the situations are closely monitored (e.g. Covid-19 saliva-tests for travellers both on arrival and departure) and all experiences (concepts, monitoring results) are transparently published.

International travelling can be connected to skiing but mostly skiing and international travelling are independent. Generally for travelling I think in place staying in case of an infection is important i.e. test before leave/travel (as of 30.11. not further discussed on this page).

ThinkThrough Two sides:

The points mentioned in skiing associated are known as risk factors for Covid transmission. Accordingly, without (adequate/aerosol) transmission preventions measures many transmissions have been linked to ski resorts in the winter 2020.

Evidence In line with theoretical risk factors (high altitude, sports, dry air in densely populated indoor rooms) - without aerosol protection measures (disinfectants and some droplet preventions were already in place in winter 2020) - many infections occurred in ski resorts.

Experiences In the summer 2020 many mountain locations in the alps were crowded and had running cable cars. To my knowledge no increased Covid-19 incidences and especially no hot-spots were observed.

=> In the summer season, when good ventilation is easy and often practiced and combined with low Covid incidence rates mountain holidays worked well.

Comment Skiing itself is safe but there need to be restrictions on the high risk skiing associated settings.

To keep in mind, high altitude and sports increase the amount of air breathed and thus aerosol transmission.

Reduction of Nightlife

A reduction of nightlife can reach from an early closure of clubs to a complete stay at home order at night.

I recently (Mid October 2020) read in the news, that people clubbing at 6 am in the morning had to go to quarantine because of a positive guest combined with a faulty guest list.

Partying until 6 am and likely drinking a lot is not wanted, since protection measures are hardly followed and the immune system is burdened the next day repairing party-damage and may not fight viruses. This is double bad:

  1. Disease progression: Longer asymptomatic phase and higher viral load.
  2. Feeling unwell the next day(s) is common and so possible Covid symptoms may be attributed to the party night and therefore are not recognized.

Reduce Alcohol Consumption

The history of prohibition dates back nearly as long, as history has been handed down. Full prohibition never really worked. Today many countries have increased taxes. The taxes mostly are high enough to reduce consumption but low enough such that smuggling doesn’t pay off.

Gastronomy

Corona Conform Schooling

As of 6.6.21 in Europe with risk groups vaccinated, protections can be relaxed. Children get only mild Covid anyways. Vaccination for children is strongly discouraged here, the mRNA vaccines are magnitudes of order more risky for children than Covid.

As of 23.8.2021: Good ventilation is the basis. Additional measures depending on the epidemiological and regional situation: Possibly masks. Possibly regular testing with a focus on teachers. Measures tailored to the local situation should work fine since students and teachers normally attend only one (or sometimes two) school(s). Continuity in time (at least a few weeks) helps acceptance and clarity. Schools are places to communicate & explain.

mostly written in October 2020 during a Corona wave peak in Europe.

Measure regarding schools can reach from complete closure to mild measures such as wearing face-masks in breaks.

References

Laboratory Biosafety

Control and Containing Measures

Appendix

Outdoors is Safer

Outdoors is safer because of:

Virion Decay

The virion decay is fast compared to other forms of life since they are fragile and can’t repair any damage. Exposed to disinfectants or soap most virions decay within a minute. Sunlight and high temperatures also render the virions un-infectious with a halflife time of a few minutes. The virions survive longest in dry air without sunlight. Even on cloudy days and towards the evening the virion halflife time is about 10 minutes.

Even our stable DNA in the inner layer of the skin, protected by outer layer of the skin which contains light absorbing melanin (the more light absorbing melanin the less sunlight reaches the inner layer of the skin), a cell membrane and inside the cell nucleus takes damage from exposure to UV. Unlike virions we also have an advanced repair mechanism which often can put things right again.

A detailed description of the coronavirus decay is on the page virion viability.

Virion Dilution

Outdoors there is much more air per person than inside:

Virion Clearance

Virion are cleared from the air by the mechanism below and due to virion decay there’s no accumulation: