The RAPID-ARIED Trial is a pragmatic, single-centre, parallel group, open-label, randomised controlled trial to be conducted in the Accident and Emergency Department of Queen Mary Hospital in Hong Kong. The investigators aim to 1) to evaluate the clinical impact of the routine application of point-of-care polymerase chain reaction (PCR) testing for targeted respiratory pathogens in the emergency department (ED) for adult patients with acute respiratory infections (ARIs) on the hospital length of stay (LOS), antiviral and antibiotic use during influenza seasons or future waves of COVID-19; and 2) to conduct a health economic analysis of such a strategy.

The investigators hypothesise that in adult patients hospitalised from the ED for ARIs during influenza seasons or COVID-19 waves, routine point-of-care PCR test for influenza A&B, SARS-CoV-2 and respiratory syncytial virus in the ED reduces the hospital LOS significantly and cost effectively compared to usual care.

In total, 1,050 adult patients who are intended to be admitted to hospital with ARIs in the ED will be recruited during influenza seasons or future waves of COVID-19 over 36 months from 2025 to 2027.

Participants will be randomised (1:1 ratio) into the interventional group and control group. A nasal swab will be collected. In the intervention group, research staff will perform PCR test using the GeneXpert® Xpress PCR kit in the ED and communicate the test results to the patient and the clinical team. In the control group, all microbiology tests will be determined by the clinical team, with retrospective PCR testing of the nasal swab sample after 28 days.

The primary outcome is the median hospital LOS. Secondary outcomes include antivirals and antibiotics use and administration time, mortality, and quality-adjusted life year, assessed using the EQ-5D-5L questionnaire.

Intention-to-treat analysis (superiority framework) and cost-effectiveness analysis (from healthcare provider perspective) will be conducted.

Study results will provide evidence regarding the optimal PCR testing strategy in the future influenza seasons and COVID-19 waves.

Inclusion Criteria:

• Adult patients aged 18 years or above
• Intended for admission to hospital with acute respiratory illness (defined as a provisional diagnosis of pneumonia, bronchitis, influenza-like illness, acute exacerbation of chronic obstructive pulmonary disease, asthma or bronchiectasis.)
• Respiratory symptoms present ≤10 days before admission to hospital
• No prior treatment with antibiotics or antivirals in the previous 14 days

Exclusion Criteria:

• Refusal of nasal or pharyngeal swabbing
• Refusal of informed consent
• Previously included in the study and re-presentation within 28 days of hospital discharge
• A prior positive test by antigen test or other PCR test for COVID-19 or influenza before ED presentation
• Exposure to FluMist® or other similar live attenuated influenza vaccines within 1 month (because such exposures may lead to a false positive PCR test result with the nasal swab sample).

IPD requires additional IRB approval because of local patient privacy ordinance.

Not applicable because this is an open-label trial.