SARS-CoV-2 Infections in Vaccinated vs Unvaccinated Healthcare Workers: Assessment of the Effectiveness of CoronaVac

Abstract

Although several vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been efficient against clinically significant coronavirus disease 2019 (COVID-19), breakthrough infections are being reported for several months. Here we conducted a prospective cohort study to assess the effectiveness of an inactive vaccine (CoronaVac; Sinovac, China) against SARS-CoV-2 by following cases of COVID-19 among vaccinated health care workers. Between March and September 2021, 1012 vaccinated and 211 unvaccinated healthcare workers from a tertiary care university hospital were followed for PCR-confirmed SARS-CoV-2 infections. COVID-19 active surveillance of the healthcare workers was carried out by the Infection Prevention and Control Unit of the institution. Anti-spike antibody values before and after COVID-19 were recorded. During a six-month follow-up program, in 35 out of 1012 (3.5%) fully vaccinated and in 16 out of 211 (7.6%) unvaccinated healthcare workers SARS-CoV-2 infections were documented. There was a statistically significant difference between vaccinated vs. unvaccinated workers regarding SARS-CoV-2 infections (P=0.003). Although all unvaccinated healthcare workers experienced symptomatic COVID-19, the vaccinated group suffered less from symptoms (100% vs. 77.1%, respectively; P=0.045). CoronaVac was 64.5% and 88.4% effective in preventing symptomatic and severe disease, respectively, and had an efficacy of 100% in preventing death among healthcare workers. In accordance with our findings, it was seen that CoronaVac could not prevent breakthrough infections, but was highly effective in preventing severe disease and death in healthcare workers for a period of six months after two consecutive doses.

Keywords

• SARS-CoV-2,
• COVID-19
• CoronaVac
• healthcare workers

Aşılı ve Aşısız Sağlık Çalışanlarında SARS-CoV-2 Enfeksiyonları: CoronaVac'ın Etkinliğinin Değerlendirilmesi

Abstract

Şiddetli akut solunum sendromu koronavirüs 2'ye (SARS-CoV-2) karşı geliştirilen birkaç aşı, klinik olarak COVID-19'a karşı etkili olmasına rağmen, halen bu virusun neden olduğu enfeksiyonlar bildirilmektedir. Bu çalışma, aşılanmış sağlık çalışanları arasında COVID-19 enfeksiyonu gelişen vakaları takip ederek aktif olmayan bir aşının (CoronaVac; Sinovac, Çin) SARS-CoV-2'ye karşı etkinliğini değerlendirmek için planlanmış prospektif bir kohort çalışmasıdır. Mart ve Eylül 2021 arasında, üçüncü basamak bir üniversite hastanesinden 1012 aşılı ve 211 aşısız sağlık çalışanı, PCR ile doğrulanmış SARS-CoV-2 enfeksiyonları için takip edildi. Sağlık çalışanlarının COVID-19 aktif tanıları kurumun Enfeksiyon Önleme ve Kontrol Birimi tarafından konuldu. Bu hastaların COVID-19 öncesi ve sonrası anti-spike antikor değerleri kaydedildi. Altı aylık bir takip programı sırasında, 1012 kişiden 35'inde (%3,5) tam aşılı ve 211 aşısız sağlık çalışanının 16'sında (%7,6) SARS-CoV-2 enfeksiyonu saptandı. Aşılı ve aşısız çalışanlar arasında SARS-CoV-2 enfeksiyonlarının geçirilmesi açısından istatistiksel olarak anlamlı bir fark vardı (P=0,003). Tüm aşılanmamış sağlık çalışanları semptomatik COVID-19 yaşamış olsa da, aşılanan grup daha hafif semptomlarla geçirdi (sırasıyla %100'e karşı %77,1; P=0,045). CoronaVac, sırasıyla semptomatik ve ciddi hastalıkları önlemede %64,5 ve %88,4 etkiliydi ve sağlık çalışanları arasında ölümü önlemede %100 etkinliğe sahipti. Bulgularımıza göre, CoronaVac'ın art arda iki dozdan sonra altı aylık bir süre boyunca sağlık çalışanlarında enfeksiyonları önleyemediği ancak ciddi hastalık ve ölümleri önlemede oldukça etkili olduğu görüldü.

Keywords

• SARS-CoV-2
• COVID-19
• CoronaVac
• sağlık çalışanları

References

1. 1. Wu Z, McGoogan JM. Characteristics of and important lessons from the coronavirus disease 2019 (COVID-19) outbreak in China: summary of a report of 72 314 cases from the Chinese Center for Disease Control and Prevention. Jama. 2020;323(13):1239-42.
2. 2. World Health Organization. Regional Office for E. Health inequity and the effects of COVID 19: assessing, responding to and mitigating the socioeconomic impact on health to build a better future. Copenhagen: World Health Organization. Regional Office for Europe; 2020 2020. Contract No.: WHO/EURO:2020-1744-41495-56594.
3. 3. Callaway E. The race for coronavirus vaccines: a graphical guide. Nature. 2020;580(7805):576-7.
4. 4. Corey L, Mascola JR, Fauci AS, Collins FS. A strategic approach to COVID-19 vaccine R&D. Science. 2020;368(6494):948-50.
5. 5. Azap-Kurt Ö AH, Erol Ç, Sarı N. Healthcare workers should be vaccinated with the highest effective vaccine available. Infect Dis Clin Microbiol 2021.3(2):107-8.
6. 6. Noh EB, Nam HK, Lee H. Which Group Should be Vaccinated First?: A Systematic Review. Infect Chemother. 2021;53(2):261-70.
7. 7. Kaur SP, Gupta V. COVID-19 Vaccine: A comprehensive status report. Virus Res. 2020;288:198114.
8. 8. Lauring AS, Hodcroft EB. Genetic Variants of SARS-CoV-2—What Do They Mean? JAMA. 2021;325(6):529-31.

9. 9. SARS-CoV-2 Variant Classifications and Definitions [Available from: https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-info.html.
10. 10. England P. Investigation of novel SARS-CoV-2 variant: variant of concern 202012/01. PHE Technical Briefing. 2020.
11. 11. Kramer V, Papazova I, Thoma A, Kunz M, Falkai P, Schneider-Axmann T, et al. Subjective burden and perspectives of German healthcare workers during the COVID-19 pandemic. European Archives of Psychiatry and Clinical Neuroscience. 2021;271(2):271-81.
12. 12. Özdemir A, Demir Çuha M, Telli Dizman G, Alp A, Metan G, Şener B. [SARS-CoV-2 Seroprevalence Among Healthcare Workers: Retrospective Analysis of the Data From A University Hospital in Turkey]. Mikrobiyol Bul. 2021;55(2):223-32.
13. 13. Jara A, Undurraga EA, González C, Paredes F, Fontecilla T, Jara G, et al. Effectiveness of an Inactivated SARS-CoV-2 Vaccine in Chile. New England Journal of Medicine. 2021;385(10):875-84.
14. 14. Bergwerk M, Gonen T, Lustig Y, Amit S, Lipsitch M, Cohen C, et al. Covid-19 breakthrough infections in vaccinated health care workers. New England Journal of Medicine. 2021;385(16):1474-84.
15. 15. Regev-Yochay G, Amit S, Bergwerk M, Lipsitch M, Leshem E, Kahn R, et al. Decreased infectivity following BNT162b2 vaccination: a prospective cohort study in Israel. The Lancet Regional Health-Europe. 2021;7:100150.
16. 16. Duarte LF, Gálvez NMS, Iturriaga C, Melo-González F, Soto JA, Schultz BM, et al. Immune Profile and Clinical Outcome of Breakthrough Cases After Vaccination With an Inactivated SARS-CoV-2 Vaccine. Frontiers in Immunology. 2021;12(3884).
17. 17. Palacios R, Batista AP, Albuquerque CSN, Patiño EG, Santos JdP, Tilli Reis Pessoa Conde M, et al. Efficacy and safety of a COVID-19 inactivated vaccine in healthcare professionals in Brazil: the PROFISCOV study. 2021.
18. 18. Tanriover MD, Doğanay HL, Akova M, Güner HR, Azap A, Akhan S, et al. Efficacy and safety of an inactivated whole-virion SARS-CoV-2 vaccine (CoronaVac): interim results of a double-blind, randomised, placebo-controlled, phase 3 trial in Turkey. Lancet. 2021;398(10296):213-22.
19. 19. Ranzani OT, Hitchings MDT, Dorion M, D'Agostini TL, de Paula RC, de Paula OFP, et al. Effectiveness of the CoronaVac vaccine in older adults during a gamma variant associated epidemic of covid-19 in Brazil: test negative case-control study. Bmj. 2021;374:n2015.