This study provides the first empirical evidence to our knowledge of the responses the public have to COVID-19 swab test results. It suggests that the public have a higher degree of trust and confidence in positive swab test results than negative when they are not given any other information accompanying the result. The experimental wording that we created for this study appeared to boost their trust in and assessment of quality of positive test results, but did not change their lower ratings of negative results. The wording used by the UK’s National Health Service, which does not include any cues of uncertainty in the result, was more likely to lead people to definitive (100% or 0%) answers to questions about the meaning of the result. The wording used by New Zealand’s Ministry of Health, which is more explicit about the reliability of the tests, appears to lead people to be more cautious about recommending that a test participant with a negative test (but still symptomatic) no longer needs to self-isolate.