Effectiveness of Inactivated COVID-19 Vaccines Against Illness Caused by the B.1.617.2 (Delta) Variant During an Outbreak in Guangdong, China

Kang, Min; Yi, Yunjeong; Li, Yan; Sun, Limei; Deng, Aiping; Hu, Ting; Zhang, Jiayi; Liu, Jun; Cheng, Mingji; Xie, Shen; Luo, Min; Jiang, Jin; Jiang, Yawen; Tang, Shixing; He, Jianfeng

doi:10.7326/m21-3509

Cited by 54 publications

(61 citation statements)

References 38 publications

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“…In our model, VE in preventing ICU admissions and deaths caused by a Delta variant infection was set at 83.6%, based on real-world VE studies in China and Brazil ( Table 1 ) [ 5 , 20 ]. Should the VE against the infection of the Delta variant be increased to >88% from 51.8% used in the baseline [ 17 ], the “adults + adolescents + children” vaccination strategy is estimated to reduce the number of deaths by 97.9% even in the absence of any NPIs, leading to <74,900 deaths over six months, similar to the annual excess respiratory disease deaths associated with influenza in China [ 45 ] (Figure S9).…”

Section: Resultsmentioning

confidence: 99%

“…Although the inactivated vaccines in use in China as of March 2022 show a relatively low effectiveness against mild and moderate disease caused by Delta variant infection [ 17 , 18 , 20 ], they appear to be highly effective against severe outcomes [ 5 , 18–20 ]. In the context of a constantly changing virus and the evolving epidemiology of the pandemic, it is of great importance to continue to ramp up efforts to increase vaccination coverage by using currently available vaccines.…”

Section: Discussionmentioning

confidence: 99%

“…We considered a two-dose vaccine with a 21-day interval between doses. Fourteen days after the second dose, the vaccine efficacy in protecting against an infection caused by the Delta variant was set at 51.8% [ 17 ]. We considered different vaccine effectiveness (VE) against each of the following clinical endpoints: infection, symptomatic disease, hospitalization, ICU admission, and death (see Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The vaccines used in mainland China were developed using historical SARS-CoV-2 lineages and have proven to be highly effective in protecting against severe illness caused by the Delta variant [ 5 , 17–20 ]. However, their effectiveness in preventing Delta infections appears to be reduced [ 17 ]. Given the lower vaccination coverage in children as compared to adults, it is legit to ask whether an epidemic caused by the importation of Delta variant infections could shift COVID-19 burden towards younger age groups and how this would affect the return to normal.…”

Section: Introductionmentioning

confidence: 99%

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Assessing the transition of COVID-19 burden towards the young population while vaccines are rolled out in China*

Cai

Yang

Deng

et al. 2022

Emerging Microbes & Infections

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SARS-CoV-2 infection causes most cases of severe illness and fatality in older age groups. Over 92% of the Chinese population aged ≥12 years has been fully vaccinated against COVID-19 (albeit with vaccines developed against historical lineages). At the end of October 2021, the vaccination programme has been extended to children aged 3–11 years. Here, we aim to assess whether, in this vaccination landscape, the importation of Delta variant infections could shift COVID-19 burden from adults to children. We developed an age-structured susceptible-infectious-removed model of SARS-CoV-2 transmission to simulate epidemics triggered by the importation of Delta variant infections and project the age-specific incidence of SARS-CoV-2 infections, cases, hospitalizations, intensive care unit admissions, and deaths. In the context of the vaccination programme targeting individuals aged ≥12 years, and in the absence of non-pharmaceutical interventions, the importation of Delta variant infections could have led to widespread transmission and substantial disease burden in mainland China, even with vaccination coverage as high as 89% across the eligible age groups. Extending the vaccination roll-out to include children aged 3–11 years (as it was the case since the end of October 2021) is estimated to dramatically decrease the burden of symptomatic infections and hospitalizations within this age group (39% and 68%, respectively, when considering a vaccination coverage of 87%), but would have a low impact on protecting infants. Our findings highlight the importance of including children among the target population and the need to strengthen vaccination efforts by increasing vaccine effectiveness.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Assessing the transition of COVID-19 burden towards the young population while vaccines are rolled out in China*

Cai

Yang

Deng

et al. 2022

Emerging Microbes & Infections

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Differences in incidence and fatality of COVID‐19 by SARS‐CoV‐2 Omicron variant versus Delta variant in relation to vaccine coverage: A world‐wide review

Wang

Liu

Zhang

et al. 2022

Journal of Medical Virology

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We aim to evaluate the evolution differences in the incidence and case fatality rate (CFR) of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) Delta and Omicron variants. The average incidence and CFRs were described between different countries. A gamma generalized linear mixed model (GLMM) was used to compare the CFRs of Delta and Omicron variants based on vaccination coverage. Totally, 50 countries were included for analyses. The incidence of coronavirus disease 2019 (COVID‐19) ranged from 0.16/100,000 to 82.95/100,000 during the Delta period and 0.03/100,000 to 440.88/100,000 during the Omicron period. The median CFRs were 8.56 (interquartile range [IQR]: 4.76–18.39) during the Delta period and 3.04 (IQR: 1.87–7.48) during the Omicron period, respectively. A total of 47 out of 50 countries showed decreased CFRs of the Omicron variant with the rate ratio ranging from 0.02 (95% confidence interval [CI]: 0.01–0.03) (in Cambodia) to 0.97 (95% CI: 0.87–1.08) (in Ireland). Gamma GLMM analysis showed that the decreased CFR was largely a result of the decreased pathogenicity of Omicron besides the increased vaccination coverage. The Omicron variant shows a higher incidence but a lower CFR around the world as a whole, which is mainly a result of the decreased pathogenicity by SARS‐CoV‐2's mutation, while the vaccination against SARS‐CoV‐2 still acts as a valuable measure in preventing people from death.

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Effectiveness of Inactivated and mRNA COVID-19 Vaccines Against SARS-CoV-2 Infection, Severe Disease and Mortality in the Geriatric Population

2023

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Older age (>60 years) has been identified as the main risk factor for COVID-19. In this study, we aimed to evaluate the efficacy of Pfizer–BioNTech and CoronaVac vaccines against COVID-19 infection, serious illness, and mortality in the geriatric population. We found that 2 doses of CoronaVac vaccine were ineffective in protecting against COVID-19 infection in people over 65 years of age, while the vaccine efficacy (VE) of the mRNA vaccine against COVID-19 was 80% (95% CI 70–87). The VE of full vaccination with BioNTech was 89% (95% CI 53–97) against hospitalization, 79% (95% CI 0–97) against death, and 79% (95% CI 0–97) against intensive care unit (ICU) admission. However, the VE of full vaccination with CoronaVac was 50% (95% CI 33–63) against hospitalization, 53% (95% CI 26–70) against ICU admission, and 56% (95% CI 30–73) against death. In conclusion, we found that the mRNA vaccine has higher efficacy against severe COVID-19 infection and mortality in the geriatric population than the inactivated vaccine. Booster doses of vaccines should be considered in increasing the effectiveness of inactivated vaccines. Given the potential of SARS-CoV-2 mutations evading vaccination protection and the risk of reduced immunity over time, regular monitoring of vaccine effectiveness in the real world is critical. Supplementary Information The online version contains supplementary material available at 10.1007/s00284-023-03322-z.

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Effectiveness of Inactivated COVID-19 Vaccines Against Illness Caused by the B.1.617.2 (Delta) Variant During an Outbreak in Guangdong, China

Cited by 54 publications

References 38 publications

Assessing the transition of COVID-19 burden towards the young population while vaccines are rolled out in China*

Assessing the transition of COVID-19 burden towards the young population while vaccines are rolled out in China*

Differences in incidence and fatality of COVID‐19 by SARS‐CoV‐2 Omicron variant versus Delta variant in relation to vaccine coverage: A world‐wide review

Effectiveness of Inactivated and mRNA COVID-19 Vaccines Against SARS-CoV-2 Infection, Severe Disease and Mortality in the Geriatric Population

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