{"id":1704,"date":"2021-11-23T08:30:00","date_gmt":"2021-11-23T13:30:00","guid":{"rendered":"https:\/\/covidqanda.org\/?p=1704"},"modified":"2021-11-23T08:30:00","modified_gmt":"2021-11-23T13:30:00","slug":"has-pcr-testing-improved-over-time","status":"publish","type":"post","link":"https:\/\/covidqanda.org\/?p=1704","title":{"rendered":"Has PCR testing improved over time?"},"content":{"rendered":"\n

Note: Happy Thanksgiving!\u00a0 Q&A will return on Tuesday, November 30th.\u00a0 In the meantime, if you have questions, please send them along.\u00a0\u00a0<\/em><\/p>\n\n\n\n

Question:<\/span><\/strong>\u00a0How sensitive and specific are the COVID tests today (I’m more curious about the PCR tests) compared to the beginning of the pandemic? If I recall correctly, it was estimated in March last year that around 1\/3 of negative tests were possibly false negatives and there were all kinds of issues with them, including CDC having problems with their own tests.\u00a0<\/p>\n\n\n\n

Answer:<\/span><\/strong>\u00a0You’re right to recall that the original PCR test that CDC developed at the beginning of the pandemic\u00a0was\u00a0deeply flawed<\/a>, so much so that it had to be recalled in mid-February 2020.\u00a0 This huge mistake stalled the U.S. pandemic response, leaving us blind to COVID spread in the early months.\u00a0 Later in 2020, we\u00a0learned<\/a>\u00a0that the original CDC test could fail up to 33% of the time.\u00a0 Since that January\/February 2020 debacle, however, COVID PCR tests have been known for their\u00a0accuracy<\/a>.\u00a0 Systems may have improved to increase throughput and to reduce testing time, but I’m not aware of improvements in PCR test sensitivity or specificity, which\u00a0have been very high<\/a>.\u00a0 The main thing that continues to change is COVID-19 incidence– as incidence increases, false positivity rates decrease and false negativity rates increase.\u00a0 I’ve included herein a\u00a0table I made last year<\/a>\u00a0to show how false negative\/positive rates depend on incidence (Table 1).\u00a0\u00a0<\/strong>And for more on sensitivity\/specificity, see\u00a0Q&A of 11\/6\/20<\/a>.<\/p>\n\n\n\n

Table 1. False negative and false positive results depend on the true level of incidence.<\/strong><\/p>\n\n\n\n

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Note: Happy Thanksgiving!\u00a0 Q&A will return on Tuesday, November 30th.\u00a0 In the meantime, if you have questions, please send them along.\u00a0\u00a0 Question:\u00a0How sensitive and specific are the COVID tests today (I’m more curious about the PCR tests) compared to the beginning of the pandemic? If I recall correctly, it was estimated in March last year […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[6,46],"tags":[121,248,249],"class_list":["post-1704","post","type-post","status-publish","format-standard","hentry","category-testing","category-trends","tag-false-negative","tag-sensitivit","tag-specificit","has-post-thumbnail","fallback-thumbnail"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/covidqanda.org\/index.php?rest_route=\/wp\/v2\/posts\/1704","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/covidqanda.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/covidqanda.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/covidqanda.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/covidqanda.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1704"}],"version-history":[{"count":1,"href":"https:\/\/covidqanda.org\/index.php?rest_route=\/wp\/v2\/posts\/1704\/revisions"}],"predecessor-version":[{"id":1706,"href":"https:\/\/covidqanda.org\/index.php?rest_route=\/wp\/v2\/posts\/1704\/revisions\/1706"}],"wp:attachment":[{"href":"https:\/\/covidqanda.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1704"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/covidqanda.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1704"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/covidqanda.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1704"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}