N.P.

О тестах:

COVID-19: точная интерпретация диагностических тестов - статистическая точка зрения

Такаши Асаи

https://link.springer.com/article/10.1007/s00540-020-02875..

If we assume that 10,000 people in Japan (prevalence of approximately 0.008%) are currently infected with the disease, and if the entire population is tested for COVID-19 using RT-PCR (with a relatively high sensitivity of 0.9 and specificity of 0.95), the theoretical distributions would be summarized, as shown in Table 3. The PPV is calculated to be 0.14%. This means that almost all people with positive test results are not infected with COVID-19.

RT-PCR is a useful diagnostic test for COVID-19, but we should adjust testing policy based on the prevalence of the disease, and should correctly interpret the test results, to establish preventive and treatment strategies, and to end the pandemic of COVID-19.

https://www.sciencedirect.com/science/article/pii/S2666634...

However, diagnostic tests are not perfect, as all tests have false positives and false negatives. As a consequence, test results cannot state definitively whether a disease (or virus) is or is not present.