{"doi":"10.1101/2022.04.08.22273571","title":"Risk and severity of SARS-CoV-2 reinfections during 2020-2022 in Vojvodina, Serbia: a population-level study","abstract":"<h4>Background</h4> Data on the rate and severity of SARS-CoV-2 reinfections in real-world settings are scarce and the effects of vaccine boosters on reinfection risk are unknown. <h4>Methods</h4> In a retrospective cohort study, registered SARS-CoV-2 laboratory-confirmed Vojvodina residents, between March 6, 2020 and October 31, 2021, were followed for reinfection ≥90 days after primary infection. Data were censored at the end of follow-up (January 31, 2022) or death. The reinfection risk was visualized with Kaplan-Meier plots. To examine the protective effect of vaccination, the subset of individuals with primary infection in 2020 (March 6-December 31) were matched (1:2) with controls without reinfection. <h4>Findings</h4> Until January 31, 2022, 13,792 reinfections were recorded among 251,104 COVID-19 primary infections (5.49%). Most reinfections (86.8%) were recorded in January 2022. Reinfections were mostly mild (99.2%). Hospitalizations were uncommon (1.8% vs . 3.70% in primary infection) and COVID-19 deaths were very rare (n=20, case fatality rate 0.15%). The overall incidence rate of reinfections was 5.99 (95% CI 5.89-6.09) per 1,000 person-months. The reinfection risk was estimated as 0.76% at six months, 1.36% at nine months, 4.96% at 12 months, 16.7% at 15 months, and 18.9% at 18 months. Unvaccinated (OR=1.23; 95%CI=1.14-1.33), incompletely (OR=1.33; 95%CI=1.08-1.64) or completely vaccinated (OR=1.50; 95%CI=1.37-1.63), were modestly more likely to be reinfected compared with recipients of a third (booster) vaccine dose. <h4>Interpretation</h4> SARS-CoV-2 reinfections were uncommon until the end of 2021 but became common with the advent of Omicron. Very few reinfections were severe. Boosters may modestly reduce reinfection risk.","journal":"medRxiv","year":2022,"id":6540,"datarank":0.12483502980788012,"base_score":0.6931471805599453,"endowment":0.6931471805599453,"self_citation_contribution":0.10397207708399181,"citation_network_contribution":0.02086295272388831,"self_endowment_contribution":0.10397207708399181,"citer_contribution":0.02086295272388831,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":1,"citers_with_citation_signal":1,"citers_with_endowment":1,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.1558,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-04-11","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":60523,"name":"Cleo Anastassopoulou","orcid":"0000-0001-7666-9198","position":1,"is_corresponding":false},{"id":60524,"name":"Zagorka Lozanov-Crvenković","orcid":"0000-0002-6188-2348","position":2,"is_corresponding":false},{"id":60525,"name":"Vladimir Vuković","orcid":"0000-0002-9561-7825","position":3,"is_corresponding":false},{"id":60526,"name":"Nataša Dragnić","orcid":"0000-0003-2938-3378","position":4,"is_corresponding":false},{"id":60527,"name":"Vladimir Petrović","orcid":"0000-0002-2052-6232","position":5,"is_corresponding":false},{"id":60528,"name":"Mioljub Ristić","orcid":"0000-0002-6923-189X","position":6,"is_corresponding":false},{"id":60529,"name":"Tatjana Pustahija","orcid":"0000-0002-6115-6709","position":7,"is_corresponding":false},{"id":60530,"name":"Zoran Gojković","orcid":"0000-0002-2659-3743","position":8,"is_corresponding":false},{"id":60531,"name":"Athanasios Tsakris","orcid":"0000-0003-0656-4715","position":9,"is_corresponding":false},{"id":148,"name":"John P. A. Ioannidis","orcid":"0000-0003-3118-6859","position":10,"is_corresponding":false},{"id":60522,"name":"Snežana Medić","orcid":"0000-0002-5778-9861","position":0,"is_corresponding":true}],"reference_count":34,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-03-01T18:20:47.508186Z","pmid":null,"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":[]}