A 30 minute rapid test (aka: lateral flow / antigen test) isn't a reliable way to test for Covid. These tests return a high rate of false negatives. You need to

A 30 minute rapid test (aka: lateral flow / antigen test) isn't a reliable way to test for Covid. These tests return a high rate of false negatives. You need to get a lab PCR test if you want an accurate result. Most countries that require Covid tests before travel require a PCR test for that reason.