このプレプリントは論文として出版されています
DOI: https://doi.org/10.20965/jdr.2023.p0004
プレプリント / バージョン2

Infectivity of omicron BA.5 comparison with original strain and other mutated strain of SARS-Cov-2 in Japan

##article.authors##

  • Kurita, Junko Department of Nursing, Faculty of Sports & Health Science ,Daitoubunka University
  • Tamie Sugawara Infectious Disease Surveillance Center, National Institute of Infectious Diseases
  • Yasushi Ohkusa Infectious Disease Surveillance Center, National Institute of Infectious Diseases

DOI:

https://doi.org/10.51094/jxiv.123

キーワード:

SARS-CoV-2、 effective reproduction number、 BA.5、 omicron、 vaccine coverage、 waning in vaccine effectiveness

抄録

Background: Pervious studies indicated that BA.5 sublineage of Omicron variant strain of SARS-CoV-2 has more infective than BA.2.

Object: The object of this study was to estimate infectivity of BA.5 controlling other factors that might affect BA.5’s infectively including vaccine effectiveness and waning, the mutated strain other than , the Olympic Games, countermeasures, and other factors that might affect BA.5’s infectively.

Method: The effective reproduction number R(t) was regressed on shares of BA.5 as well as  vaccine coverage, vaccine coverage with some delay, temperature, humidity, mobility, share of the other mutated strains, counter measures including Go To Travel Campaign and an Olympic Games and countermeasures. The study period was February, 2020 through July 22, 2022, as of August 12, 2022.

Results : We selected the specification with 120 days lag of waning. In this specification, mobility, some state of emergency, vaccine coverage and those with lag, and proportion of delta and omicron BA.2 were significant with the expected sign. Conversely, proportion of omicron BA.1 were significant but with the unexpected sign. The estimated coefficient of BA.5 was negative but insignificant. Goto Travel Campaign was significantly negative and thus it reduced infectively. The Olympic games was negative but in significant and thus it did not raise infectively.

Discussion: The obtained estimated results showed that BA.5 did not have higher infectivity than the original strain and lower than delta or omicron BA.2 variant strains. Though it might be inconsistent the previous research, this study might be more reliable than the previous studies. Because BA.5. outbreak had not cease yet and we cannot predict its dynamics, the estimated BA.5 infectivity will change over time.

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引用文献

European Centre for Disease Prevention and Control. Epidemiological update: SARS-CoV-2 Omicron sub-lineages BA.4 and BA.5. https://www.ecdc.europa.eu/en/news-events/epidemiological-update-sars-cov-2-omicron-sub-lineages-ba4-and-ba5 [accessed on August 22, 2022]

National Intitute of Infectious Diseases. Updated Situation of COVID-19 Outbreak (July 13,2022) https://www.niid.go.jp/niid/ja/2019-ncov/11309-covid19-ab90th.html (in Japanese) [accessed on August 20, 2022]

Japan Ministry of Health, Labour and Welfare. Press Releases. https://www.mhlw.go.jp/stf/newpage_10723.html (in Japanese) (accessed August18, 2022).

Kurita J, Sugawara T, Ohkusa Y. Estimating Event Ban Effects on COVID-19 Outbreak in Japan. Journal of Health Science and Development 2021. 4: https://www.innovationinfo.org/articles/JHSD/JHSD-137.pdf

Tokyo metropolitan Government. Data of COVID-19 monitoring meeting in metropolitan Tokyo. https://www.bousai.metro.tokyo.lg.jp/taisaku/saigai/1013388/index.html (in Japanese) (accessed August 21,2022)

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投稿日時: 2022-07-25 05:01:51 UTC

公開日時: 2022-07-26 09:28:56 UTC — 2022-09-06 04:36:22 UTCに更新

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改版理由

The study period has been extended.
研究分野
一般医学・社会医学・看護学