# Comparative Performance of COVID-19 Test Methods in Healthcare Workers during the Omicron Wave

## TL;DR

This study compares the effectiveness of different COVID-19 testing methods in healthcare workers during the Omicron wave, finding that PCR tests, especially saliva-based ones, are the most reliable.

## Contribution

The study provides a systematic comparison of multiple testing methods against a gold standard during the Omicron wave, including saliva-based PCR.

## Key findings

- PCR tests, particularly saliva PCR, showed the highest sensitivity for detecting SARS-CoV-2.
- Nasal rapid antigen tests had lower sensitivity compared to PCR but offered convenience and accessibility.
- Oropharyngeal rapid antigen tests were the least sensitive among all tested methods.

## Abstract

The COVID-19 pandemic presents unique requirements for accessible, reliable testing, and many testing platforms and sampling techniques have been developed over the course of the pandemic. Not all test methods have been systematically compared to each other or a common gold standard, and the performance of tests developed in the early epidemic have not been consistently re-evaluated in the context of new variants. We conducted a repeated measures study with adult healthcare workers presenting for SARS-CoV-2 testing. Participants were tested using seven testing modalities. Test sensitivity was compared using any positive PCR test as the gold standard. A total of 325 individuals participated in the study. PCR tests were the most sensitive (saliva PCR 0.957 ± 0.048, nasopharyngeal PCR 0.877 ± 0.075, oropharyngeal PCR 0.849 ± 0.082). Standard nasal rapid antigen tests were less sensitive but roughly equivalent (BinaxNOW 0.613 ± 0.110, iHealth 0.627 ± 0.109). Oropharyngeal rapid antigen tests were the least sensitive (BinaxNOW 0.400 ± 0.111, iHealth brands 0.311 ± 0.105). PCR remains the most sensitive testing modality for the diagnosis of COVID-19 and saliva PCR is significantly more sensitive than oropharyngeal PCR and equivalent to nasopharyngeal PCR. Nasal AgRDTs are less sensitive than PCR but have benefits in convenience and accessibility. Saliva-based PCR testing is a viable alternative to traditional swab-based PCR testing for the diagnosis of COVID-19.