{"doi":"10.1093/aje/kwad059","title":"COVID-19 Vaccine Safety Surveillance in Early Pregnancy in the United States: Design Factors Affecting the Association Between Vaccine and Spontaneous Abortion","abstract":"In the Vaccine Safety Datalink (VSD), we previously reported no association between coronavirus disease 2019 (COVID-19) vaccination in early pregnancy and spontaneous abortion (SAB). The present study aims to understand how time since vaccine rollout or other methodological factors could affect results. Using a case-control design and generalized estimating equations, we estimated the odds ratios (ORs) of COVID-19 vaccination in the 28 days before a SAB or last date of the surveillance period (index date) in ongoing pregnancies and occurrence of SAB, across cumulative 4-week periods from December 2020 through June 2021. Using data from a single site, we evaluated alternative methodological approaches: increasing the exposure window to 42 days, modifying the index date from the last day to the midpoint of the surveillance period, and constructing a cohort design with a time-dependent exposure model. A protective effect (OR = 0.78, 95% confidence interval: 0.69, 0.89), observed with 3-cumulative periods ending March 8, 2021, was attenuated when surveillance extended to June 28, 2021 (OR = 1.02, 95% confidence interval: 0.96, 1.08). We observed a lower OR for a 42-day window compared with a 28-day window. The time-dependent model showed no association. Timing of the surveillance appears to be an important factor affecting the observed vaccine-SAB association.","journal":"American Journal of Epidemiology","year":2023,"id":359153,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":10,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9316,"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":624519,"name":"Jacob L. Haapala","orcid":null,"position":1,"is_corresponding":false},{"id":339235,"name":"Heather S. Lipkind","orcid":"0009-0001-9846-7965","position":2,"is_corresponding":false},{"id":371262,"name":"Malini B. DeSilva","orcid":"0000-0003-3705-1672","position":3,"is_corresponding":false},{"id":710256,"name":"Jingyi Zhu","orcid":"0009-0008-1725-5305","position":4,"is_corresponding":false},{"id":371264,"name":"Matthew F. Daley","orcid":"0000-0003-1309-4096","position":5,"is_corresponding":false},{"id":360570,"name":"Darios Getahun","orcid":"0000-0003-3610-8841","position":6,"is_corresponding":false},{"id":360572,"name":"Nicola P. Klein","orcid":"0000-0003-1777-4814","position":7,"is_corresponding":false},{"id":623220,"name":"Kimberly K. Vesco","orcid":"0000-0001-9934-6383","position":8,"is_corresponding":false},{"id":371265,"name":"Stephanie A. Irving","orcid":"0000-0001-7437-6797","position":9,"is_corresponding":false},{"id":360573,"name":"Jennifer C. Nelson","orcid":"0000-0002-2782-2050","position":10,"is_corresponding":false},{"id":720984,"name":"Joshua T.B. Williams","orcid":"0000-0001-6811-5611","position":11,"is_corresponding":false},{"id":371267,"name":"Simon J. Hambidge","orcid":"0000-0002-7535-0668","position":12,"is_corresponding":false},{"id":361179,"name":"James G. Donahue","orcid":"0000-0002-5594-7715","position":13,"is_corresponding":false},{"id":1109781,"name":"Candace C. Fuller","orcid":"0000-0002-8902-1435","position":14,"is_corresponding":false},{"id":360574,"name":"Eric Weintraub","orcid":"0000-0003-0375-0504","position":15,"is_corresponding":false},{"id":443017,"name":"Christine K. Olson","orcid":null,"position":16,"is_corresponding":false},{"id":360566,"name":"Elyse O. Kharbanda","orcid":"0000-0003-1806-6502","position":17,"is_corresponding":false},{"id":360567,"name":"Gabriela Vazquez‐Benitez","orcid":"0000-0002-6226-3207","position":0,"is_corresponding":true}],"reference_count":32,"raw_metadata":null,"created_at":"2026-07-19T01:13:52.889556Z","pmid":"36928091","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":[]}