Infectivity of omicron BA.5 comparison with original strain and other mutated strain of SARS-Cov-2 in Japan
キーワード:SARS-CoV-2、 effective reproduction number、 BA.5、 omicron、 vaccine coverage、 waning in vaccine effectiveness
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.
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)
Levin EG, Lustig Y, Cohen C, et al. Waning Immune Humoral Response to BNT162b2 Covid-19 Vaccine over 6 Months. N Engl J Med 2021:NEJMoa2114583.
Chemaitelly H, Tang P, Hasan MR, et al. Waning of BNT162b2 Vaccine Protection against SARS-CoV-2 Infection in Qatar. N Engl J Med. 2021:NEJMoa2114114.
Polack FP, Thomas SJ, Kitchin N, et al. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. N Engl J Med. 2020;383:2603-15.
Chung H, He S, Nasreen S, et al. Effectiveness of BNT162b2 and mRNA-1273 covid-19 vaccines against symptomatic SARS-CoV-2 infection and severe covid-19 outcomes in Ontario, Canada: test negative design study. BMJ 2021;374.
Dagan N, Barda N, Kepten E, Miron O, Perchik S, Katz MA, Hernan MA, Lipsitch M, Reis B, Balicer RD. BNT162b2 mRNA Covid-19 vaccine in a nationwide mass vaccination setting. N Engl J Med 2021;384:1412-23.
Vasileiou E, Simpson CR, Shi T, et al. Interim findings from first-dose mass COVID-19 vaccination roll-out and COVID-19 hospital admissions in Scotland: a national prospective cohort study. Lancet 2021;397:1646-57.
Bernal JL, Andrews N, Gower C, Robertson C, Stowe J, Tessier E, Simmons R, Cottrell S, Roberts R, O'Doherty M, Brown K, Cameron C, Stockton D, McMenamin J, Ramsay M. Effectiveness of the Pfizer–BioNTech and Oxford–AstraZeneca vaccines on Covid-19 related symptoms, hospital admissions, and mortality in older adults in England: test negative case-control study. BMJ 2021;373:n1088.
Bjork J, Inghammar M, Moghaddassi M, Rasmussen M, Malmqvist U, Kahn F. Effectiveness of the BNT162b2 vaccine in preventing COVID-19 in the working age population: first results from a cohort study in southern Sweden. Infect Dis (Lond) 2021;1-6.
Pawlowski C, Lenehan P, Puranik A, Agarwal V, Venkatakrishnan AJ, Niesen MJM, O'Horo JC, Virk A, Swift MD, Badley AD, Halamka J, Soundararajan V. FDA-authorized COVID-19 vaccines are effective per real-world evidence synthesized across a multi-state health system. Med (N Y) 2021;2:979-92.e8.
Li B, Deng A, Li K, et al. Viral infection and transmission in a large, well-traced outbreak caused by the SARS-CoV-2 Delta variant. medRxiv 2021.07.07.21260122; doi: https://doi.org/10.1101/2021.07.07.21260122
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
- 2022-09-06 04:36:22 UTC（2）
- 2022-07-26 09:28:56 UTC（1）
改版理由The study period has been extended.
この作品は、Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licenseの下でライセンスされています。