Implementation and adherence to regular asymptomatic testing in a COVID-19 vaccine trial

Area of Science:

• Vaccinology
• Infectious Diseases
• Clinical Trials

Background:

• Evaluating vaccine efficacy (VE) against asymptomatic infections is crucial for understanding epidemiological impact.
• Regular testing for subclinical infections requires high participant adherence and minimal false positives.
• This study details the implementation and adherence to weekly testing in a COVID-19 vaccine trial.

Purpose of the Study:

• To assess the feasibility and adherence of a weekly asymptomatic testing strategy in a COVID-19 vaccine trial.
• To analyze factors influencing adherence to regular testing protocols.
• To estimate the probability of detecting true and false positive asymptomatic infections.

Main Methods:

• The COV002 trial utilized weekly self-administered RT-PCR swabs to detect asymptomatic SARS-CoV-2 infections.
• Mixed-effects regression models analyzed adherence rates.
• Probabilities of true and false positive infections were estimated based on adherence and testing characteristics.

Main Results:

• Over 356,000 tests were conducted by 10,811 participants during 13 months.
• Median adherence was 75.0%, with a 74.5% probability of detecting asymptomatic infections.
• Adherence declined weekly and was influenced by age, sex, and occupation; higher adherence observed in older adults, females, and non-healthcare workers.

Conclusions:

• The COV002 trial successfully demonstrated the feasibility of a long-term asymptomatic testing strategy.
• Findings provide valuable insights for designing future Phase III vaccine trials where infection is a key outcome.
• This approach can enhance the assessment of vaccine impact on transmission.