Contact Tracing Study

I’m starting to explore Contact Tracing .. a critical part in detecting the spread.

Some learnings from an early release CDC paper titled “COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020” that I came across today. The Abstract:

During January 26–February 10, 2020, an outbreak of 2019 novel coronavirus disease in an air-conditioned restaurant in Guangzhou, China, involved 3 family clusters. The airflow direction was consistent with droplet transmission. To prevent the spread of the virus in restaurants, we recommend increasing the distance between tables and improving ventilation.

Now it’s important to note that this an early release .. but it contains a lot of contact tracing research. Aa few bits from the report .. many of which we’ve already learned:

• COVID-19 is spread by respiratory droplets (visible drops or invisible aerosol).
• It can stay infectious in the droplets.
• The lighter droplets can ‘hang’ in the air.
• Air movement can transmit the lighter droplets.

We also know:

• COVID-19 is incredibly infectious, and may be the most infections in the early stages.
• Human-to-human transmission was proven early.
• The incubation period is long enough to allow someone who has it to travel virtually anywhere on the planet.
• Infected are capable of spreading the virus when showing no symptoms.

This snap from the CDC study:

• A restaurant. Large tables are circles, small circles are people.
• Three feet between tables.
• A1 is the index patient.
• The air in the room is in motion.
• Dates of infection noted.

The report goes into more detail .. describing the AC unit has an intake which explains how air could move back to Table C, infecting two people there.

So, knowing this, we must take into account many aspects of social gatherings:

• Distance apart from each other.
• Duration together (longer exposer time heightens the risk).
• Number of people.
• The physical environment (in this case, air movement is a significant factor)
• Masks .. not to protect us, but to protect others from us.

Lots to learn.

Stay connected. Stay safe. Stay home.