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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Russian Journal of Infection and Immunity</journal-id><journal-title-group><journal-title xml:lang="en">Russian Journal of Infection and Immunity</journal-title><trans-title-group xml:lang="ru"><trans-title>Инфекция и иммунитет</trans-title></trans-title-group></journal-title-group><issn publication-format="print">2220-7619</issn><issn publication-format="electronic">2313-7398</issn><publisher><publisher-name xml:lang="en">SPb RAACI</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">17967</article-id><article-id pub-id-type="doi">10.15789/2220-7619-SPA-17967</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>ORIGINAL ARTICLES</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>ОРИГИНАЛЬНЫЕ СТАТЬИ</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">SSA post-analysis of COVID-19 incidence magnitude in Novosibirsk Region</article-title><trans-title-group xml:lang="ru"><trans-title>Постанализ данных по заболеваемости COVID-19 методом SSA на примере Новосибирской области</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-1126-2148</contrib-id><name-alternatives><name xml:lang="en"><surname>Petrakova</surname><given-names>Viktoriya S.</given-names></name><name xml:lang="ru"><surname>Петракова</surname><given-names>Виктория Сергеевна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>PhD (Physics and Mathematics), Senior Researcher, Researcher</p></bio><bio xml:lang="ru"><p>к.ф.-м.н., старший научный сотрудник, научный сотрудник</p></bio><email>vika-svetlakova@yandex.ru</email><xref ref-type="aff" rid="aff1"/><xref ref-type="aff" rid="aff2"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Institute of Computational Modeling SB RAS</institution></aff><aff><institution xml:lang="ru">Институт вычислительного моделирования СО РАН</institution></aff></aff-alternatives><aff-alternatives id="aff2"><aff><institution xml:lang="en">Sobolev Institute of Mathematics SB RAS</institution></aff><aff><institution xml:lang="ru">Институт математики им. Соболева СО РАН</institution></aff></aff-alternatives><pub-date date-type="preprint" iso-8601-date="2025-07-30" publication-format="electronic"><day>30</day><month>07</month><year>2025</year></pub-date><pub-date date-type="pub" iso-8601-date="2026-03-30" publication-format="electronic"><day>30</day><month>03</month><year>2026</year></pub-date><volume>16</volume><issue>1</issue><issue-title xml:lang="en"/><issue-title xml:lang="ru"/><fpage>175</fpage><lpage>186</lpage><history><date date-type="received" iso-8601-date="2025-07-16"><day>16</day><month>07</month><year>2025</year></date><date date-type="accepted" iso-8601-date="2025-07-27"><day>27</day><month>07</month><year>2025</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2026, Petrakova V.S.</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2026, Петракова В.С.</copyright-statement><copyright-year>2026</copyright-year><copyright-holder xml:lang="en">Petrakova V.S.</copyright-holder><copyright-holder xml:lang="ru">Петракова В.С.</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://iimmun.ru/iimm/article/view/17967">https://iimmun.ru/iimm/article/view/17967</self-uri><abstract xml:lang="en"><p>The article is aimed at conducting post-analysis of COVID-19 epidemiological data in Novosibirsk for the period from 2020 to 2023. The study emphasizes the importance of data post-analysis for understanding the dynamics of SARS-CoV-2 spread and the characteristics of its impact on public health. The study results make possible to assess of how population susceptibility to different virus strains has changed, what is the difference between an outbreak of diseases associated with the emergence of a new virus strain and its seasonal infection spread. There was applied the SSA method for analyzing time series to separate them into components as well as studying key indicators such as the number of new infections, deaths, critical cases, hospitalizations, and ventilator-dependent patients in the Novosibirsk region. Three main components have been identified for the described data sets: a general trend that reflects changes in the rate of virus spread related to spread of new strains, as well as periodic phenomena associated with virus strains and seasonality. The results show that a significant part of the changes in disease dynamics is accounted for by the emergence of new strains, but also due to «chronicity» epidemic with seasonal fluctuations. The observed relationships and time lags between the number of critically-ill patients and the number of recorded deaths due to COVID-19, as well as between the number of hospitalized patients and ventilator-dependent patients are shown. Thus, it is concluded that the identified trend depicting a change between the number of infected people and development of virus strains can be useful for refining the parameters of mathematical models for COVID-19 spread. The SEIR-HCD differential model, which was previously used to simulate the disease spread in the Novosibirsk region, was chosen as an illustrative example. It is shown that the parameter of the virus spread rate, restored through the selected trend, when introduced into the model, provides a smaller modeling error than the if it was generated using the solution of the inverse issue.</p></abstract><trans-abstract xml:lang="ru"><p>Статья посвящена преимущественно постанализу эпидемиологических данных о COVID-19 в Новосибирске за период с 2020 по 2023 гг. с использованием метода сингулярного спектрального анализа (Singular spectrum analysis, SSA). Предложен литературный обзор работ, посвященный анализу данных различного типа, описывающих эпидемиологическую ситуацию во время пандемии в различных регионах мира. Показано, что превалирующая часть работ написана и посвящена описанию первого начального этапа развития эпидемии (2020 г.). Работы по постанализу данных о многолетней динамики вируса SARS-CoV-2 фактически отсутствуют. Исследование подчеркивает важность постанализа данных для понимания динамики распространения вируса и особенностей его воздействия на здоровье населения. Результаты проведенного исследования позволяют оценить, как менялась восприимчивость населения к разным штаммам вируса, в чем отличие вспышки заболеваемости, связанной с появлением нового штамма вируса, от сезонного распространения инфекции. Для анализа в статье используется метод SSA, применяемый к анализу временных рядов для разделения их на составляющие. Метод применялся для изучения ключевых показателей, таких как количество новых заражений, смертей, числа критических случаев, числа госпитализированных и числа пациентов, находящихся на ИВЛ в Новосибирской области. Для описанных наборов данных выделяются три основные компоненты: общий тренд, который отражает изменение скорости распространения вируса с распространением новых штаммов; периодическая компонента, связанная со сменой штамма вируса, и сезонная компонента. Результаты показывают, что значительная часть изменений в динамике заболеваний обусловлена появлением новых штаммов, но также проявляется и «фоновая» эпидемия с сезонными колебаниями. Это подчеркивает необходимость учитывать множество факторов, влияющих на распространение вируса, включая иммунитет, методы лечения и качество медицинской помощи. Показаны наблюдаемые взаимосвязи и временные лаги между количеством больных в критическом состоянии и количеством зафиксированных смертей от вируса, а также между количеством госпитализированных больных и пациентов, находящихся на ИВЛ. Сделан вывод о том, что выделенный тренд показывающий, как менялось число инфицированных с развития штаммов, может быть полезен для уточнения параметров математических моделей распространения COVID-19. В качестве иллюстративного примера выбрана дифференциальная модель SEIR-HCD, которая ранее использовалась для моделирования распространения заболеваемости в Новосибирской области. Показано, что параметр скорости распространения вируса, восстановленный по выделенному тренду, при подстановке его в модель дает меньшую ошибку моделирования, чем восстановленный с помощью решения обратной задачи.</p></trans-abstract><kwd-group xml:lang="en"><kwd>COVID-19 incidence data</kwd><kwd>post-analysis of data</kwd><kwd>SSA method</kwd><kwd>SEIR-HCD model</kwd><kwd>epidemiological models</kwd><kwd>time series analysis</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>данные по заболеваемости COVID-19</kwd><kwd>постанализ данных</kwd><kwd>SSA-метод</kwd><kwd>SEIR-HCD модель</kwd><kwd>эпидемиологические модели</kwd><kwd>анализ временных рядов</kwd></kwd-group><funding-group><award-group><funding-source><institution-wrap><institution xml:lang="ru">Министерство науки и высшего образования РФ</institution></institution-wrap><institution-wrap><institution xml:lang="en">Ministry of Science and Higher Education of the Russian Federation</institution></institution-wrap></funding-source><award-id>FWNF-2024-0002</award-id></award-group><funding-statement xml:lang="en">The work was carried out within the framework of the state scientific assignment to the Sobolev Institute of Mathematics of the Siberian Branch of the Russian Academy of Sciences, project FWNF-2024-0002.</funding-statement><funding-statement xml:lang="ru">Работа выполнена в рамках государственного научного задания Институту математики им. 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