Assessing the COVID-19 vaccination program during the Omicron variant (B.1.1.529) epidemic in early 2022, Tokyo.
COVID-19
Direct effect
Immunization
Indirect effect
Population-level impact
Journal
BMC infectious diseases
ISSN: 1471-2334
Titre abrégé: BMC Infect Dis
Pays: England
ID NLM: 100968551
Informations de publication
Date de publication:
31 Oct 2023
31 Oct 2023
Historique:
received:
22
04
2023
accepted:
25
10
2023
medline:
2
11
2023
pubmed:
1
11
2023
entrez:
1
11
2023
Statut:
epublish
Résumé
Many countries, including high-income nations, struggled to control epidemic waves caused by the Omicron variant (B.1.1.529), which had an antigenically distinct evolution. Evaluating the direct and indirect effects of vaccination during the Omicron waves is essential to assess virus control policies. The present study assessed the population impacts of a vaccination program during the sixth wave caused by BA.1 and BA.2 from January to May 2022, in Tokyo. We analyzed the primary series and booster vaccination coverages and the confirmed cases stratified by vaccination history. We estimated the number of COVID-19 cases that were directly and indirectly prevented by vaccination. To estimate the direct impact, we used a statistical model that compared risks between unvaccinated and vaccinated individuals. A transmission model employing the renewal process was devised to quantify the total effect, given as the sum of the direct and indirect effects. Assuming that the reporting coverage of cases was 25%, mass vaccination programs, including primary and booster immunizations, directly averted 640,000 COVID-19 cases (95% confidence interval: 624-655). Furthermore, these programs directly and indirectly prevented 8.5 million infections (95% confidence interval: 8.4-8.6). Hypothetical scenarios indicated that we could have expected a 19% or 7% relative reduction in the number of infections, respectively, compared with the observed number of infections, if the booster coverage had been equivalent to that of the second dose or if coverage among people aged 10-49 years had been 10% higher. If the third dose coverage was smaller and comparable to that of the fourth dose, the total number of infections would have increased by 52% compared with the observed number of infections. The population benefit of vaccination via direct and indirect effects was substantial, with an estimated 65% reduction in the number of SARS-CoV-2 infections compared with counterfactual (without vaccination) in Tokyo during the sixth wave caused by BA.1 and BA.2.
Sections du résumé
BACKGROUND
BACKGROUND
Many countries, including high-income nations, struggled to control epidemic waves caused by the Omicron variant (B.1.1.529), which had an antigenically distinct evolution. Evaluating the direct and indirect effects of vaccination during the Omicron waves is essential to assess virus control policies. The present study assessed the population impacts of a vaccination program during the sixth wave caused by BA.1 and BA.2 from January to May 2022, in Tokyo.
METHODS
METHODS
We analyzed the primary series and booster vaccination coverages and the confirmed cases stratified by vaccination history. We estimated the number of COVID-19 cases that were directly and indirectly prevented by vaccination. To estimate the direct impact, we used a statistical model that compared risks between unvaccinated and vaccinated individuals. A transmission model employing the renewal process was devised to quantify the total effect, given as the sum of the direct and indirect effects.
RESULTS
RESULTS
Assuming that the reporting coverage of cases was 25%, mass vaccination programs, including primary and booster immunizations, directly averted 640,000 COVID-19 cases (95% confidence interval: 624-655). Furthermore, these programs directly and indirectly prevented 8.5 million infections (95% confidence interval: 8.4-8.6). Hypothetical scenarios indicated that we could have expected a 19% or 7% relative reduction in the number of infections, respectively, compared with the observed number of infections, if the booster coverage had been equivalent to that of the second dose or if coverage among people aged 10-49 years had been 10% higher. If the third dose coverage was smaller and comparable to that of the fourth dose, the total number of infections would have increased by 52% compared with the observed number of infections.
CONCLUSIONS
CONCLUSIONS
The population benefit of vaccination via direct and indirect effects was substantial, with an estimated 65% reduction in the number of SARS-CoV-2 infections compared with counterfactual (without vaccination) in Tokyo during the sixth wave caused by BA.1 and BA.2.
Identifiants
pubmed: 37907865
doi: 10.1186/s12879-023-08748-1
pii: 10.1186/s12879-023-08748-1
pmc: PMC10619277
doi:
Substances chimiques
COVID-19 Vaccines
0
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
748Subventions
Organisme : Japan Society for the Promotion of Science
ID : 21K10495
Organisme : Japan Society for the Promotion of Science
ID : 21H03198 and 22K19670
Organisme : Ministry of Health, Labour and Welfare
ID : 20CA2024, 20HA2007, 21HB1002, and 21HA2016
Organisme : Japan Agency for Medical Research and Development
ID : JP 23fk0108685
Organisme : Environmental Restoration and Conservation Agency
ID : JPMEERF20S11804
Organisme : Strategic International Collaborative Research Program
ID : JPMJSC20U3 and JPMJSC2105
Organisme : Research Institute of Science and Technology for Society
ID : JPMJRS22B4
Informations de copyright
© 2023. The Author(s).
Références
Lancet Reg Health Am. 2023 Jan;17:100396
pubmed: 36437904
N Engl J Med. 2022 Apr 21;386(16):1532-1546
pubmed: 35249272
Lancet Infect Dis. 2021 Jul;21(7):962-974
pubmed: 33743846
Lancet Reg Health West Pac. 2022 Nov;28:100571
pubmed: 35971514
Lancet Reg Health Am. 2022 Jan;5:100085
pubmed: 34746912
Lancet Infect Dis. 2022 Mar;22(3):357-366
pubmed: 34562375
Cell Rep Med. 2022 Mar 11;3(4):100583
pubmed: 35480627
Int J Infect Dis. 2022 Jan;114:252-260
pubmed: 34800687
J Epidemiol Community Health. 2020 Nov;74(11):964-968
pubmed: 32535550
Nat Med. 2023 Feb;29(2):348-357
pubmed: 36652990
Lancet Reg Health Am. 2023 Jan;17:100398
pubmed: 36437905
N Engl J Med. 2021 Apr 15;384(15):1412-1423
pubmed: 33626250
Science. 2020 Nov 13;370(6518):763-765
pubmed: 33087460
Euro Surveill. 2022 Jun;27(22):
pubmed: 35656831
Lancet Infect Dis. 2022 Sep;22(9):1293-1302
pubmed: 35753318
Expert Rev Vaccines. 2023 Jan-Dec;22(1):90-103
pubmed: 36519401
Int J Surg. 2020 Apr;76:71-76
pubmed: 32112977
Sci Rep. 2023 Apr 4;13(1):5540
pubmed: 37016060
Nat Commun. 2022 Feb 1;13(1):612
pubmed: 35105889
Science. 2021 Apr 9;372(6538):
pubmed: 33658326
Sci Transl Med. 2022 Jun;14(647):eabn9836
pubmed: 35412326
Int J Epidemiol. 1991 Mar;20(1):300-10
pubmed: 2066239
N Engl J Med. 2023 Feb 23;388(8):764-766
pubmed: 36734847
Nature. 2022 Mar;603(7902):700-705
pubmed: 35104835
Signal Transduct Target Ther. 2022 May 7;7(1):151
pubmed: 35525870
J Epidemiol. 2022 Feb 5;32(2):105-111
pubmed: 34776499
Emerg Infect Dis. 2022 Sep;28(9):1777-1784
pubmed: 35820166
N Engl J Med. 2020 Dec 31;383(27):2603-2615
pubmed: 33301246
Nat Commun. 2022 Sep 30;13(1):5760
pubmed: 36180438