Per tests for infection are flawed
Executive summary
Widespread changes in testing behavior and surveillance capacity mean official case counts and some surveillance metrics now underestimate true respiratory-virus circulation; experts and public-health outlets report that home tests and reduced reporting have lowered visibility into COVID-19 trends [1] [2]. Government surveillance systems still provide reliable signals for severe outcomes—hospitalizations and characterized viruses—but those systems are smaller, lagged, and not designed to count every infection [3] [4].
1. Testing has moved out of view: home tests and lower reporting
Public-health communicators and health systems say a large share of diagnostic activity now happens outside formal reporting channels: many people use at‑home antigen tests that are not reported to health departments or choose not to test at all, so "official case counts underestimate the actual prevalence of COVID-19" [1]. News outlets and researchers also note global case reports are likely low because testing has slowed internationally, producing a systematic under‑capture of infections [2].
2. Surveillance still tracks severe disease reliably — but with limits
Systems that monitor hospitalizations and lab‑confirmed severe illness—such as COVID‑NET and FluView—continue to provide dependable measures of burden because they rely on laboratory confirmation within healthcare settings; COVID‑NET counts people hospitalized with a positive lab test within 14 days of admission, giving a stable denominator for severe outcomes [3]. Influenza surveillance similarly reports hospitalization rates and virus characterization data, but these measures are low‑volume and can lag behind rapid changes in transmission [4].
3. Case counts ≠ circulation: positivity and composite signals matter
Because routine case reporting no longer captures most mild and unreported infections, public‑health interpretation shifts to other signals: test positivity where available, hospitalization rates, genomic sampling, and wastewater or sentinel surveillance. Nebraska Medicine emphasizes that when test positivity exceeds 5% transmission is considered uncontrolled, signaling the value of interpreting multiple indicators rather than raw case totals [1] [4].
4. Genomic surveillance and variant tracking remain active but resource‑limited
European and U.S. agencies continue to assess and designate variants of concern and sequence circulating viruses, and CDC and ECDC report ongoing genetic characterization of hundreds of viruses to understand variant proportions [5] [4]. However, reporting gaps and smaller sample sizes can delay recognition of new sublineages, a problem acknowledged in broader critiques of pandemic-era data flows and strained surveillance capacity [6].
5. Media and experts note higher underlying incidence despite low reported counts
Journalistic summaries and scientific commentators point out rising infections even when official counts are muted: outlets cite WHO and researchers saying global reported cases are rising but almost certainly undercount true incidence because testing has slowed, reinforcing that low official numbers are not proof of low transmission [2].
6. What this means for individuals and policymakers
For individuals: testing remains useful when symptomatic because treatments and isolation decisions depend on knowing your status; clinicians and public‑health advice still recommend testing to guide care [7] [2]. For policymakers: reliance on case counts alone is misleading; decisions should weigh hospitalizations, variant surveillance, test positivity, and sentinel systems, and invest in restoring robust, timely data flows that were criticized as weak during earlier pandemic phases [6] [4].
7. Disagreements and unanswered questions in the record
Sources agree testing and reporting gaps reduce case visibility, but they offer different emphases: clinical outlets urge continued individual testing and treatment access [7], while news analyses stress surveillance and data‑system shortcomings [6] [2]. Available sources do not mention precise estimates of what fraction of infections are missed in current U.S. reporting or offer a single authoritative correction factor—those figures are not found in current reporting (not found in current reporting).
8. Bottom line: tests are imperfect measures; use multiple lenses
Tests themselves are not "flawed" in a binary sense—laboratory assays and antigen kits retain diagnostic value—but the public‑health meaning of reported test counts has changed because of who tests and whether results are reported. Interpreters must combine hospitalization metrics, test positivity, sequencing, and sentinel data to understand real circulation, and policymakers should rebuild reporting pathways if they want case counts to again reflect true incidence [1] [3] [4].