There are different approaches countries consider and decide how to combat COVID-19. Obviously there are only few "case studies" with real experiences, so it is too early to say which method is best.

In general there are 4 main approaches that one can consider:
Also, it needs to be noted that a country can change its strategy such as starting with "lockdown" and then move to "extensive testing and isolate" scenario to buy time and to get sufficient test facilities up and running. We explain below each of the approaches.

Showing differences in approaches between late reaction, complete lockdown and extensive testing with isolation

1. Do nothing

Doing nothing and to not consider anything to combat the virus is the approach countries take at early stages or who do not believe it is a danger to its population. And in some cases business and economic interests supercede peoples' wishes.  

In this case the virus may continue to grow with a daily fatality rate of 1.35 (see Formula of Fatality Rate based on China and Italy early stages). It may stop till it reaches a state where no more people infect each other that is estimated between 50-70% of infected people, the so-called (herd or group immunity threshold). 

As in this scenario number of infections will grow rapidly and may overwhelm the healthcare system, that is not only a risk to the ones getting infected heavily, but also to all other medical urgencies such as operations, baby deliveries etc. 

2. Lockdown

Lockdown is the approach China used, and even they engaged it very late, it shows results. The lockdown timeline in China is around 55 days, but if lockdown is enabled earlier on, it could erradicate the virus within 4 weeks.

The lockdown needs to be very strict. Just closing schools and restaurants does not seem to significantly lower the exponential infection and fatality rate. Even an informal lockdown does not seem to work efficiently from the existing data sets publicly available. 

The only way to lower the infection and fatality rate with this method is to do an enforced lockdown at the moment. People can go to supermarkets and pharmacies, bring children between divorced parents and most urgent jobs (such as medical and enforcement personnel) are still in place, but all other people stay at home. China enforced use of masks and also quarantine all infected people in hotels, isolated from their families to avoid spreading the illness to more people.

The number of fatalities is slowing down after approximately 3 weeks. Once number of infections and fatalities slow down to single digit numbers, then the country can start opening up again slowly. It needs to keep a serious check at any incoming ports/airports/roads and may even need a quarantine for all incoming people till a vaccin is found or world situation stabilizes.

3. Extensive Testing and Contain 

Another strategy certain countries such as South Korea does, is doing extensive testing and isolate people who are tested positive. In cases where there are larger communities or locations involved, they can put a specific lockdown for those areas.

This does not involve a complete lockdown of the economy, but assumes the following conditions:
1. There are sufficient number of tests available
2. People still need to take precaution when going out, and take social distancing
3. All borders need to be protected as well to avoid incoming new cases.

The very first condition is very important for this scenario as if not all cases can be isolated, then this can turn quickly into an uncontrolled explosion of infections.

The strategy has worked in South Korea and lowered the number of new infections and fatalities. However, this strategy could take more time to stabilize than a full lockdown.

South Korea #Fatalities since 11 March 2020
Formula to calculate #Fatalities with full lockdown*

*Formula as defined in COVID-19 Fatality Rate Formula based on Existing Datasets

Based on the early experiences from China and South Korea when they were both stabilizing, it looks like this scenario is approximately 35% slower in time than the full lockdown approach. But it must be said that current existing data sets are too small to confirm this final conclusion.

Germany is doing both extensive testing and lockdown and its fatality rate is one of the lowest in the world with stands currently at 1.40% (4 April 2020).

4. Herd Immunity 

Some countries are trying herd or group immunity. This strategy is based on the fact that if a certain part of population already has been infected and healed, in this case the young ones and economically most active, then the virus cannot spread anymore and will erradicate as well. 

It assumes the following conditions:
1. the virus does not have fatal impact on the young and economically active people that are exposed,
2. People cannot get re-infected again,
3. The vulnerable patients are strongly protected during this period, 
4. Still, to avoid scenario 1, it needs to slow down physical movements to avoid overloading healthcare system, but if done well, it gets the country immune if the threshold level is reached. 

In this case, for instance, children can still play with others in small groups, and people can still go out, but measures need to put in place to slowdown the exponential growth of the virus such as:

  • social distancing encouraged
  • public events banned
  • school closure ordered and 
  • case based self isolation mandated.

The UK estimates that between 50-70% needs to be infected to get this group immunity. If the conditions are well met, it may work, but this approach has not yet been proven with this specific virus. 

To get to that level of infections in a controlled manner, not to overload #beds available, for a large popluation, it could take a longer period. In case of a population of 10 million people, you need at least 5 million (50%) infected. Assuming that 1% needs to be on Intensive Care (IC) 2 weeks each and there is a maximum capacity of 2,000 available IC beds , that calculates to 1 year to maintain that situation to get that level.  

The UK on 23rd of March did a headturn to go from this approach to a full lockdown approach. Sweden is taking this approach.

Imperial College did research what different measures countries took to avoid high infection rate and shows the different approaches countries took.


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