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He X, Liao Y, Liang Y, Yu J, Gao W, Wan J, Liao Y, Su J, Zou X, Tang S. Transmission characteristics and inactivated vaccine effectiveness against transmission of the SARS-CoV-2 Omicron BA.2 variant in Shenzhen, China. Front Immunol 2024; 14:1290279. [PMID: 38259438 PMCID: PMC10800792 DOI: 10.3389/fimmu.2023.1290279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 12/13/2023] [Indexed: 01/24/2024] Open
Abstract
We conducted a retrospective cohort study to evaluate the transmission risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2 variant and the effectiveness of inactivated COVID-19 vaccine boosters in Shenzhen during a BA.2 outbreak period from 1 February to 21 April 2022. A total of 1,248 individuals were infected with the BA.2 variant, and 7,855 close contacts were carefully investigated. The risk factors for the high secondary attack rate of SARS-CoV-2 infection were household contacts [adjusted odds ratio (aOR): 1.748; 95% confidence interval (CI): 1.448, 2.110], younger individuals aged 0-17 years (aOR: 2.730; 95% CI: 2.118, 3.518), older persons aged ≥60 years (aOR: 1.342; 95% CI: 1.135, 1.588), women (aOR: 1.442; 95% CI: 1.210, 1.718), and the subjects exposed to the post-onset index cases (aOR: 8.546; 95% CI: 6.610, 11.050), respectively. Compared with the unvaccinated and partially vaccinated individuals, a relatively low risk of secondary attack was found for the individuals who received booster vaccination (aOR: 0.871; 95% CI: 0.761, 0.997). Moreover, a high transmission risk was found for the index cases aged ≥60 years (aOR: 1.359; 95% CI: 1.132, 1.632), whereas a relatively low transmission risk was observed for the index cases who received full vaccination (aOR: 0.642; 95% CI: 0.490, 0.841) and booster vaccination (aOR: 0.676; 95% CI: 0.594, 0.770). Compared with full vaccination, booster vaccination of inactivated COVID-19 vaccine showed an effectiveness of 24.0% (95% CI: 7.0%, 37.9%) against BA.2 transmission for the adults ≥18 years and 93.7% (95% CI: 72.4%, 98.6%) for the adults ≥60 years, whereas the effectiveness was 51.0% (95% CI: 21.9%, 69.3%) for the individuals of 14 days to 179 days after booster vaccination and 51.2% (95% CI: 37.5%, 61.9%) for the non-household contacts. The estimated mean values of the generation interval, serial interval, incubation period, latent period, and viral shedding period were 2.7 days, 3.2 days, 2.4 days, 2.1 days, and 17.9 days, respectively. In summary, our results confirmed that the main transmission route of Omicron BA.2 subvariant was household contact, and booster vaccination of the inactivated vaccines was relatively effective against BA.2 subvariant transmission in older people.
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Affiliation(s)
- Xiaofeng He
- Department of Epidemiology, School of Public Health, Southern Medical University, Guangzhou, China
- Institute of Evidence-Based Medicine, Heping Hospital Affiliated to Changzhi Medical College, Changzhi, China
| | - Yuxue Liao
- Office of Emergency, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Yuanhao Liang
- Department of Epidemiology, School of Public Health, Southern Medical University, Guangzhou, China
| | - Jiexin Yu
- Third Class of 2019 of Clinical Medicine, Suzhou Medical College, Soochow University, Suzhou, Jiangsu, China
| | - Wei Gao
- Office of Emergency, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Jia Wan
- Office of Emergency, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Yi Liao
- Office of Emergency, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Jiao Su
- Department of Biochemistry, Changzhi Medical College, Changzhi, China
| | - Xuan Zou
- Office of Emergency, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Shixing Tang
- Department of Epidemiology, School of Public Health, Southern Medical University, Guangzhou, China
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
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Meehan MT, Hughes A, Ragonnet RR, Adekunle AI, Trauer JM, Jayasundara P, McBryde ES, Henderson AS. Replicating superspreader dynamics with compartmental models. Sci Rep 2023; 13:15319. [PMID: 37714942 PMCID: PMC10504364 DOI: 10.1038/s41598-023-42567-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 09/12/2023] [Indexed: 09/17/2023] Open
Abstract
Infectious disease outbreaks often exhibit superspreader dynamics, where most infected people generate no, or few secondary cases, and only a small fraction of individuals are responsible for a large proportion of transmission. Although capturing this heterogeneity is critical for estimating outbreak risk and the effectiveness of group-specific interventions, it is typically neglected in compartmental models of infectious disease transmission-which constitute the most common transmission dynamic modeling framework. In this study we propose different classes of compartmental epidemic models that incorporate transmission heterogeneity, fit them to a number of real outbreak datasets, and benchmark their performance against the canonical superspreader model (i.e., the negative binomial branching process model). We find that properly constructed compartmental models can capably reproduce observed superspreader dynamics and we provide the pathogen-specific parameter settings required to do so. As a consequence, we also show that compartmental models parameterized according to a binary clinical classification have limited support.
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Affiliation(s)
- Michael T Meehan
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, 4811, Australia.
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, 4811, Australia.
| | - Angus Hughes
- School of Public Health and Preventive Medicine, Monash University, Melbourne, 3800, Australia
| | - Romain R Ragonnet
- School of Public Health and Preventive Medicine, Monash University, Melbourne, 3800, Australia
| | - Adeshina I Adekunle
- Defence Science and Technology Group, Department of Defence, Melbourne, 3207, Australia
| | - James M Trauer
- School of Public Health and Preventive Medicine, Monash University, Melbourne, 3800, Australia
| | - Pavithra Jayasundara
- School of Public Health and Preventive Medicine, Monash University, Melbourne, 3800, Australia
| | - Emma S McBryde
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, 4811, Australia
| | - Alec S Henderson
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, 4811, Australia
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Zhao S, Guo Z, Sun S, Hung CT, Leung EYM, Wei Y, Wang H, Li K, Yam CHK, Chow TY, Gao J, Jia KM, Chong KC, Yeoh EK. Effectiveness of BNT162b2 and Sinovac vaccines against the transmission of SARS-CoV-2 during Omicron-predominance in Hong Kong: A retrospective cohort study of COVID-19 cases. J Clin Virol 2023; 166:105547. [PMID: 37453162 DOI: 10.1016/j.jcv.2023.105547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 06/30/2023] [Accepted: 07/09/2023] [Indexed: 07/18/2023]
Abstract
BACKGROUND In 2022, SARS-CoV-2 Omicron variants circulated globally, generating concerns about increased transmissibility and immune escape. Hong Kong, having an infection-naive population with a moderate 2-dose vaccine coverage (63% by the end of 2021), experienced a COVID-19 epidemic largely seeded by Omicron BA.2 variants that led to the greatest outbreak in the region to date. Little remains known about the protection of commonly-administered vaccines against transmission of Omicron BA.2 variants. METHODS In this retrospective cohort study, we identified 17 535 laboratory-confirmed COVID-19 cases using contact tracing information during the Omicron-predominant period between January and June 2022 in Hong Kong. Demographic characteristics, time from positive test result to case reporting, isolation, or hospital admission, as well as contact tracing history and contact setting were extracted. Transmission pairs were reconstructed through suspected epidemiological links according to contact tracing history, and the number of secondary cases was determined for each index case as a measurement for risk of transmission. The effectiveness of mRNA vaccine (BNT162b2) and inactivated vaccine (Sinovac) against transmission of BA.2 variants was estimated using zero-inflated negative binomial regression models. RESULTS Vaccine effectiveness against transmission for patients who received the 2-dose BNT162b2 vaccine was estimated at 56.2% (95% CI: 14.5, 77.6), 30.6% (95% CI: 13.0, 44.6), and 21.3% (95% CI: 2.9, 36.2) on 15 - 90, 91 - 180, and 181 - 270 days after vaccination, respectively, showing a significant decrease over time. For 3-dose vaccines, vaccine effectiveness estimates were 41.0% (95% CI: 11.3, 60.7) and 41.9% (95% CI: 6.1, 64.0) on 15 - 180 days after booster doses of Sinovac and BNT162b2, respectively. Although significant vaccine effectiveness was detected in household settings, no evidence of such protective association was detected in non-household settings for either Sinovac or BNT162b2. CONCLUSION Moderate and significant protection against Omicron BA.2 variants' transmission was found for 2 and 3 doses of Sinovac or BNT162b2 vaccines. Although protection by 2-dose BNT162b2 may evidently wane with time, protection could be restored by the booster dose. Here, we highlight the importance of continuously evaluating vaccine effectiveness against transmission for emerging SARS-CoV-2 variants.
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Affiliation(s)
- Shi Zhao
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China; CUHK Shenzhen Research Institute, Shenzhen, China; Centre for Health Systems and Policy Research, Chinese University of Hong Kong, Hong Kong, China
| | - Zihao Guo
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Shengzhi Sun
- Department of Epidemiology and Biostatistics, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Chi Tim Hung
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Eman Yee Man Leung
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Yuchen Wei
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Huwen Wang
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Kehang Li
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Carrie Ho Kwan Yam
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Tsz Yu Chow
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Jian Gao
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Katherine Min Jia
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - Ka Chun Chong
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China; CUHK Shenzhen Research Institute, Shenzhen, China; Centre for Health Systems and Policy Research, Chinese University of Hong Kong, Hong Kong, China.
| | - Eng-Kiong Yeoh
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China; Centre for Health Systems and Policy Research, Chinese University of Hong Kong, Hong Kong, China
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