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

## TL;DR

The paper introduces a simple, low-cost method for collecting and storing saliva samples on paper to study SARS-CoV-2 and track symptoms over time.

## Contribution

The novel contribution is a scalable, non-invasive system for community-based SARS-CoV-2 sampling and symptom tracking using ordinary paper.

## Key findings

- SARS-CoV-2 RNA was detected in all nine symptomatic or exposed individuals but not in one asymptomatic person.
- RNA remained stable on paper for up to 70 days at room temperature and four months when frozen.
- The method is easy to implement, inexpensive, and suitable for large-scale community studies.

## Abstract

To develop a biological diary (CoronaCal) that allows anyone in the community to collect and store serial saliva samples and chart symptoms on ordinary printer paper.

Diaries were analyzed for the presence of SARS-CoV-2 RNA using established polymerase chain reaction (PCR) procedures. CoronaCal diaries were distributed to volunteer subjects in the community during the peak of the COVID-19 outbreak in New York. Volunteers collected their own daily saliva samples and self-reported symptoms.

SARS-CoV-2 RNA extracted from CoronaCals was measured using qPCR and RNA levels were correlated with reported symptoms. SARS-CoV-2 RNA was detected in CoronaCals from nine of nine people with COVID-19 symptoms or exposure to someone with COVID-19, and not in one asymptomatic person. CoronaCals were stored for up to 70 days at room temperature during collection and then frozen for up to four months before analysis, suggesting that SARS-CoV-2 RNA is stable once dried onto paper.

Sampling saliva on simple paper provides a useful method to study the natural history and epidemiology of COVID-19. The CoronaCal collection and testing method is easy to implement, inexpensive, non-invasive and scalable. The approach can inform the historical and epidemiological understanding of infections in individuals and populations.