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We estimated vaccine effectiveness (VE) against severe COVID-19 during October 2021, using Slovenian surveillance data. For people fully vaccinated with any vaccine in age groups 18–49, 50–64, ≥ 65 years, VE was 86% (95% CI: 79–90), 89% (85–91), and 77% (74–81). Among ≥ 65 year-olds fully vaccinated with mRNA vaccines, VE decreased from 93% (95% CI: 88–96) in those vaccinated ≤ 3 months ago to 43% (95% CI: 30–54) in those vaccinated ≥ 6 months ago, suggesting the need for early boosters.


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  1. National institute of Public Health (NIJZ). Cepljenje proti COVID-19 v Sloveniji. [Vaccination against COVID-19 in Slovenia]. Ljubljana: NIJZ. [Accessed: 2 Dec 2021]. Slovenian. Available from: https://app.powerbi.com/view?r=eyJrIjoiYWQ3NGE1NTMtZWJkMi00NzZmLWFiNDItZDc5YjU5MGRkOGMyIiwidCI6ImFkMjQ1ZGFlLTQ0YTAtNGQ5NC04OTY3LTVjNjk5MGFmYTQ2MyIsImMiOjl9
  2. Klavs I, Serdt M, Učakar V, Grgič-Vitek M, Fafangel M, Mrzel M, et al. Enhanced national surveillance of severe acute respiratory infections (SARI) within COVID-19 surveillance, Slovenia, weeks 13 to 37 2021. Euro Surveill. 2021;26(42):2100937.  https://doi.org/10.2807/1560-7917.ES.2021.26.42.2100937  PMID: 34676822 
  3. National institute of Public Health (NIJZ). Elektronski register cepljenih oseb in neželenih učinkov po cepljenju. [Electronic Registry of vaccinated individuals and adverse events following vaccinations]. Ljubljana: NIJZ. [Accessed: 2 Dec 2021]. Slovenian. Available from: https://www.nijz.si/sl/elektronski-register-cepljenih-oseb-in-nezelenih-ucinkov-po-cepljenju-erco
  4. Seppälä E, Veneti L, Starrfelt J, Danielsen AS, Bragstad K, Hungnes O, et al. Vaccine effectiveness against infection with the Delta (B.1.617.2) variant, Norway, April to August 2021. Euro Surveill. 2021;26(35):2100793.  https://doi.org/10.2807/1560-7917.ES.2021.26.35.2100793  PMID: 34477054 
  5. Lopez Bernal J, Andrews N, Gower C, Gallagher E, Simmons R, Thelwall S, et al. Effectiveness of Covid-19 vaccines against the B.1.617.2 (Delta) variant. N Engl J Med. 2021;385(7):585-94.  https://doi.org/10.1056/NEJMoa2108891  PMID: 34289274 
  6. Tenforde MW, Self WH, Naioti EA, Ginde AA, Douin DJ, Olson SM, et al. Sustained Effectiveness of Pfizer-BioNTech and Moderna Vaccines Against COVID-19 Associated Hospitalizations Among Adults - United States, March-July 2021. MMWR Morb Mortal Wkly Rep. 2021;70(34):1156-62.  https://doi.org/10.15585/mmwr.mm7034e2  PMID: 34437524 
  7. Harder T, Külper-Schiek W, Reda S, Treskova-Schwarzbach M, Koch J, Vygen-Bonnet S, et al. Effectiveness of COVID-19 vaccines against SARS-CoV-2 infection with the Delta (B.1.617.2) variant: second interim results of a living systematic review and meta-analysis, 1 January to 25 August 2021. Euro Surveill. 2021;26(41):2100920.  https://doi.org/10.2807/1560-7917.ES.2021.26.41.2100920  PMID: 34651577 
  8. Puranik A, Lenehan PJ, Silvert E, Niesen MJ, Corchado-Garcia J, O’Horo JC, et al. Comparison of two highly-effective mRNA vaccines for COVID-19 during periods of Alpha and Delta variant prevalence. medRxiv. 2021:2021.08.06.21261707v3.  https://doi.org/10.1101/2021.08.06.21261707 
  9. Thompson MG, Stenehjem E, Grannis S, Ball SW, Naleway AL, Ong TC, et al. Effectiveness of Covid-19 Vaccines in Ambulatory and Inpatient Care Settings. N Engl J Med. 2021;385(15):1355-71.  https://doi.org/10.1056/NEJMoa2110362  PMID: 34496194 
  10. European Centre for Disease Prevention and Control (ECDC). Interim analysis of COVID-19 vaccine effectiveness against Severe Acute Respiratory Infection due to laboratory-confirmed SARS-CoV-2 among individuals aged 65 years and older, ECDC multi-country study. Stockholm: ECDC; 8 Oct 2021. Available from: https://www.ecdc.europa.eu/en/publications-data/interim-analysis-covid-19-vaccine-effectiveness-against-severe-acute-respiratory
  11. Israel A, Merzon E, Schäffer AA, Shenhar Y, Green I, Golan-Cohen A, et al. Elapsed time since BNT162b2 vaccine and risk of SARS-CoV-2 infection: test negative design study. BMJ. 2021;375:e067873.  https://doi.org/10.1136/bmj-2021-067873  PMID: 34819275 
  12. Chemaitelly H, Tang P, Hasan MR, AlMukdad S, Yassine HM, Benslimane FM, et al. Waning of BNT162b2 Vaccine Protection against SARS-CoV-2 Infection in Qatar. N Engl J Med. 2021:NEJMoa2114114.
  13. Goldberg Y, Mandel M, Bar-On YM, Bodenheimer O, Freedman L, Haas EJ, et al. Waning Immunity after the BNT162b2 Vaccine in Israel. N Engl J Med. 2021:NEJMoa2114228.
  14. Havervall S, Ng H, Jernbom Falk A, Greilert-Norin N, Månberg A, Marking U, et al. Robust humoral and cellular immune responses and low risk for reinfection at least 8 months following asymptomatic to mild COVID-19. J Intern Med. 2021;joim.13387.; Epub ahead of print.  PMID: 34459525 

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