The Coronavirus Calendar (CoronaCal): a simplified SARS-CoV-2 test system for sampling and retrospective analysis

Area of Science:

• Virology
• Epidemiology
• Biotechnology

Background:

• The COVID-19 pandemic highlighted the need for accessible and scalable methods for disease surveillance.
• Traditional diagnostic methods can be resource-intensive and may not capture real-time epidemiological trends effectively.

Purpose of the Study:

• To develop and validate a novel biological diary system, CoronaCal, for community-based collection and storage of serial saliva samples.
• To assess the feasibility of using ordinary printer paper as a medium for preserving viral RNA for diagnostic analysis.
• To correlate the presence and levels of SARS-CoV-2 RNA in saliva with self-reported symptoms.

Main Methods:

• CoronaCal diaries were distributed to community volunteers during the COVID-19 outbreak in New York.
• Volunteers collected daily saliva samples on paper and self-reported symptoms.
• SARS-CoV-2 RNA was extracted from the paper samples and detected using quantitative polymerase chain reaction (qPCR).

Main Results:

• SARS-CoV-2 RNA was detected in samples from all symptomatic individuals (9/9) with reported COVID-19 symptoms or exposure.
• No SARS-CoV-2 RNA was detected in samples from one asymptomatic individual.
• SARS-CoV-2 RNA remained stable on paper for up to 70 days at room temperature and for an additional four months when frozen, indicating RNA stability.

Conclusions:

• Saliva sampling on paper using the CoronaCal method is a viable approach for studying the natural history and epidemiology of COVID-19.
• The CoronaCal system is non-invasive, inexpensive, easy to implement, and scalable for widespread use.
• This method offers valuable insights into infection dynamics at both individual and population levels.