Visualizing the Chain of SARS-CoV-2 Infection in Luxembourg

Context: The SARS-CoV-2 positive cases had an unabated near-exponential rise in a matter of days across almost all of Europe, starting at some point in October 2020, and eventually topped 2 to 4 times the maximun cases recorded in individual countires (first wave), and Luxembourg was no exception. These recent high numbers with the ‘background data’ during first wave may have an interesting outlook, one being to find the ‘chain-of-infections’ and if it has deviated from the first-wave or not. It is NOT about finding the first cases but if we could manage to compartmentalize the recent cases into different variables, like ‘sectors’, ‘age-groups’, ‘regions (for bigger countries)’, etc. and then make a chart of daily cases across these variables, theoretically it is possible to check if there was a ‘chain-of-infections’ between the variables or not.

Data: We have limited data for different variables available publicly and to test the theory, here we have used the variable ‘age-groups’ (Luxembourg resident population) and them plotted against the weekly number of positive cases (Mon-Sun). Since the ‘age-groups’ are made up of different ‘size’ (number of people in each age-group), we normalized the cases by per 1,000 of each age-group for comparison purposes.

Assumptions: Before the observations are presented below, please note that certain assumptions are necessary but may not be 100% accurate. First assumption would be that every week the number of tests done are evenly distributed (pro-rata) amongst all age-groups. While, if the number of tests in each groups is available, then we could have normalized the number of tests and had a more accurate assumption, but without this data, we have to assume that the tests were evenly distributed amongst the age-groups. A second assumption would be that majority of each age-group ‘socializes’ with the same age group. Without this assumption, it would be hard to follow the chain within the same age-group and which slowly progresses to other age-groups.
Both these assumptions are critical for the abservations below.

Observations: Following a sudden increase in cases in 14-20 Sep. 2020, the chain continued through 10-19y olds and progressed to other age-groups. A second chain emerged in parallel in the 80y or older people and more-or-less had a different pattern than the rest of the population. This is easy to understand as these cases are mostly in the old-age care and nursing homes, who have limited social interactions with the rest of the population, but once contracted, the infections speard through the care-facilities quickly.

These two observations are interesting, especially in the view that the old-age care and nursing homes are now under constant vigilance and the care-givers are more informed about the situation and can intervene quickly. Hence we anticipate that the situation would not detoriate in the old-age care and nursing homes as during the second wave (Oct-Dec 2020).

In light of the recent emergence of SARS-CoV-2 variants deemed ‘highly-transmissible’ (first cases detected in Luxembourg as early as Dec 2020), the latest data for 1-7 Feb 2021 show the new cases are mostly driven by very young (0-19y) age group – common space would be education and care-centers, and (30-49y) age-group – mostly made up of economic professionals, with he social dynamics being similar as during the second wave.

In short, social distancing would play a bigger and critical role during the current crisis due to the ‘highly-transmissible’ variants compared to other hygiene measures (masks, disinfectants, etc.).

If you are using a smartphone or a small-display, please rotate the device to ‘landscape view’ for better visualization

Following text is an ‘OPINION’ and should be interpreted with CAUTION!

It would be highly recommended to create a ‘communication campaign’ for everyone but also targetted for 15-30y olds to limit social interactions and how individual ‘actions’ translate into ‘ripple-effects’ in the current crisis. It would also be important to create new ideas and spaces for social-interaction as alternate options for young individuals and professionals (temporary and open space food, music, entertainment, events, etc.), both as a sense of normalization and as a lifeline to the economic-sectors.

In contrast, the child-care facilities like nurseries and primary education would remain a challenge in foreseeable future due to practical reasons, and therefore new and innovative ideas are required for a sustainable model. Due to the high transmissibility, ‘RNA sequencing’ for varaint dterminaton is not practical (time constraint) and would probably need to rely on rapid-antigen test for quick and immediate intervention (quarantine for individual and first degree of contacts)

first published : 28.11.2020
data updated: 11.02.2021

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