COVID-19 has caused hundreds of millions of infections and hundreds of
deaths, and even though vaccinations are increasing, the mutation of the
virus makes the pandemic even difficult to control. Existing manual,
operator and Bluetooth-based technologies for epidemiological
investigation and close contact tracing suffer from high cost, low
accuracy, and difficulty in scaling up. Viruses such as Delta variants
have a greater ability to survive and spread, making many of the
existing human-human close contacts tracing less effective. Also, it is
easy to overlook the fact that there is still a large segment of the
world's population that does not have access to the Internet and is
proficient in using smartphones, which makes the performance of smart
device-based tracing much less effective. Inspired by Health Code and
Tracetogether, which have been widely accepted in China and Singapore,
we propose a LoRa and blockchain-based contact tracing method LBTrace,
which is low-power, lightweight, and operation-free. The experimental
results demonstrate the high stability and accuracy of our proposed
method, which can be used as a complement to existing methods to help
some governments effectively control COVID-19 and future outbreaks under
certain emergency conditions.