COVID-19 estimated test detection windows for IgG, IgM and nasal PCR tests

by nonzerosum1 min read11th May 2020No comments

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Coronavirus
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I spent a while looking for this information online and found it hard to come by, so I've compiled my research conclusions. These numbers are based on the best information I could find, but please comment with any critique or improvements.

Background info

There are two types of COVID tests. Molecular tests and serological tests.

Molecular tests are the nasal swab tests, also referred to as PCR tests.

Serological tests are the antibody tests, which can be done by a blood drop or a draw of blood.

How soon would you test positive for covid? How soon after exposure would a covid test be positive?

  • Nasal swab PCR test: you'd likely test positive around 3-4 days after you catch it (but can be anywhere from 1-12 days after)
  • Antibody IgG test: 10-28 days after catching it (i.e. wait till 28 days after expected exposure to be more confident)
  • Antibody IgM test: 7-14 days after catching it

Will you test positive for covid if you're asymptomatic?

  • You can test positive for covid while being asymptomatic.
  • If you caught it, on average you'd develop symptoms 5 days after exposure, but it can be anywhere from 2 days to never.
  • You'd most likely test positive via nasal swab 3-4 days after getting it.

Overall (average) timeline

  • Say you're exposed to COVID-19 on day 0.
  • You'd become contagious on day 2.
  • You'd test positive via nasal swab on day 3 or day 4 (but can be anywhere from day 1-12).
  • You'd develop symptoms on day 4 (but can be anywhere from 3-14 days or never).
  • You'd test positive on an IgM antibody test on day 10 (can be anywhere from 7-14 days).
  • You'd test positive on an IgG antibody test on day 21 (but can be 10-28 days).
  • Your symptoms would likely last a total of 1-2 weeks in a mild case, or 6+ weeks in a more severe case.
  • You'd no longer be contagious 10-14 days after your last symptom resolves.

Some references: https://www.health.harvard.edu/diseases-and-conditions/if-youve-been-exposed-to-the-coronavirus, https://notadoctor.substack.com/p/are-covid-19-symptoms-changing-and, https://allcarefamilymed.com/covid19-antibody-test, https://jcm.asm.org/content/early/2020/05/07/JCM.00941-20

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