{"doi":"10.1093/cid/ciad582","title":"The New Normal: Delayed Peak SARS-CoV-2 Viral Loads Relative to Symptom Onset and Implications for COVID-19 Testing Programs","abstract":"BACKGROUND: Early in the coronavirus disease 2019 (COVID-19) pandemic, peak viral loads coincided with symptom onset. We hypothesized that in a highly immune population, symptom onset might occur earlier in infection, coinciding with lower viral loads. METHODS: We assessed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A viral loads relative to symptom duration in symptomatic adults (≥16 years) presenting for testing in Georgia (4/2022-4/2023; Omicron variant predominant). Participants provided symptom duration and recent testing history. Nasal swabs were tested by Xpert Xpress SARS-CoV-2/Flu/RSV assay and cycle threshold (Ct) values recorded. Nucleoprotein concentrations in SARS-CoV-2 polymerase chain reaction (PCR)-positive samples were measured by single molecule array. To estimate hypothetical antigen rapid diagnostic test (Ag RDT) sensitivity on each day after symptom onset, percentages of individuals with Ct value ≤30 or ≤25 were calculated. RESULTS: Of 348 newly-diagnosed SARS-CoV-2 PCR-positive individuals (65.5% women, median 39.2 years), 317/348 (91.1%) had a history of vaccination, natural infection, or both. By both Ct value and antigen concentration measurements, median viral loads rose from the day of symptom onset and peaked on the fourth/fifth day. Ag RDT sensitivity estimates were 30.0%-60.0% on the first day, 59.2%-74.8% on the third day, and 80.0%-93.3% on the fourth day of symptoms.In 74 influenza A PCR-positive individuals (55.4% women; median 35.0 years), median influenza viral loads peaked on the second day of symptoms. CONCLUSIONS: In a highly immune adult population, median SARS-CoV-2 viral loads peaked around the fourth day of symptoms. Influenza A viral loads peaked soon after symptom onset. These findings have implications for ongoing use of Ag RDTs for COVID-19 and influenza.","journal":"Clinical Infectious Diseases","year":2023,"id":321274,"datarank":0.5775221402565088,"base_score":3.8501476017100584,"endowment":3.8501476017100584,"self_citation_contribution":0.5775221402565088,"citation_network_contribution":0.0,"self_endowment_contribution":0.5775221402565088,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":46,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9632,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2023-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1033286,"name":"Richard Parsons","orcid":"0000-0002-5691-0084","position":1,"is_corresponding":false},{"id":1033954,"name":"Kaleb B. McLendon","orcid":null,"position":2,"is_corresponding":false},{"id":928672,"name":"Adrianna Westbrook","orcid":"0000-0001-9309-6205","position":3,"is_corresponding":false},{"id":337554,"name":"Wilbur A. Lam","orcid":"0000-0002-0325-7990","position":4,"is_corresponding":false},{"id":24174,"name":"Greg S. Martin","orcid":"0000-0002-9684-7593","position":5,"is_corresponding":false},{"id":376971,"name":"Nira R. Pollock","orcid":"0000-0002-6396-2915","position":6,"is_corresponding":false},{"id":377303,"name":"Jennifer K. Frediani","orcid":"0000-0002-4634-0591","position":0,"is_corresponding":true}],"reference_count":25,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T01:07:32.611759Z","pmid":"37768707","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}