The disease burden and clinical severity of the SARS-CoV-2 Omicron BA.2 sublineage outbreak in Shanghai

In a recent study posted to medRxiv*, researchers estimated the severity and burden of coronavirus disease 2019 (COVID-19) in a recent outbreak in Shanghai, China.

Study: Estimation of disease burden and clinical severity of COVID-19 caused by Omicron BA.2 in Shanghai, February-June 2022. Image Credit: Lady Jiff/Shutterstock
Study: Estimation of disease burden and clinical severity of COVID-19 caused by Omicron BA.2 in Shanghai, February-June 2022. Image Credit: Lady Jiff/Shutterstock

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources

Background

A COVID-19 outbreak occurred in Shanghai from February 2022 to June 2022 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2 sub-variant. The government imposed stringent non-pharmaceutical interventions (NPIs) and stratified sub-districts into non-high- and high-risk areas based on the number of cases. Multiple rounds of nucleic acid testing were performed in non-high- and high-risk areas.

Nonetheless, these measures were inadequate to contain community transmission. On April 1, 2022, a lockdown was enforced that ended on June 1, 2022. Estimating the severity and burden of the disease is crucial to strategize appropriate interventions and plan for adequate health care requirements.

About the study

In the present study, the authors estimated the incidence of SARS-CoV-2 infections, severe/critical cases, and deaths to evaluate the disease burden in early 2022 in Shanghai. Infections were confirmed by reverse-transcription polymerase chain reaction (RT-PCR) tests. Patients were classified as mild if they presented with fever, loss of smell/taste, and fatigue without pneumonia. Moderate cases exhibited typical respiratory symptoms and radiographic evidence of pneumonia.

Cases were classified as severe if they developed: low oxygen saturation, breathing difficulty, low arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) ratio, or progressive symptoms with imaging analysis revealing progressive lesions within 24-to-48 hours. Patients were deemed critical if admitted to the intensive care unit (ICU). PCR-positive individuals who showed no clinically identifiable signs/symptoms or pneumonia were categorized as asymptomatic. 

Relevant data were extracted from Shanghai Municipal Health Commission. The authors investigated the incidence of infections, severe/critical cases, and deaths. They computed the proportion of asymptomatic patients (P­asym), infection fatality risk (IFR), symptomatic case fatality risk (sCFR), risk of severe/critical disease due to infection (ISR), and risk of severe/critical illness from symptomatic disease (sCSR).

Pasym was estimated as the ratio of the number of asymptomatic cases to the total number of infections. ISR was defined as the ratio of the number of severe/critical cases to total PCR-positive cases. sCSR was the ratio of severe/critical cases to the number of symptomatic cases. IFR was the ratio between the number of deaths and total infections. sCFR was the number of deaths to the total number of symptomatic patients.

Findings

Between February 26 and June 30, 2022, more than 627,110 cases were reported in Shanghai, with 588 deaths. Overall, the infection rate was 2.74 per 100 individuals. The highest infection rate (3.65) was noted among those aged 60 – 79 and the lowest (1.67) in children aged 3 – 17. The proportion of severe/critical cases was the highest in older adults (> 80 years) at 125.29 per 100,000 individuals and the lowest in those aged 3 – 17 (< 0.001).

The rate of mortality was 2.42, with the highest rate of 57.17 per 100,000 individuals in older adults (> 80 years), 4.6 in 60 – 79 age group, 0.32 for people aged 40 – 59, 0.02 for 18-to-39-year-old individuals and 0 for those aged 3-to-17 years. The Pasym was 90.7% by June 30, 2022. The overall IFR was 0.09% for people < 60 years, 0.13% for those in the 60 – 79 age group, and 1.99% for people aged ≥ 80.

Notably, among individuals ≥ 80 years, the IFR was 2.22% for non-vaccinated individuals and 0.25% for those vaccinated with at least one dose. The ISR was 0.23%, with the highest risk of 4.35% for older adults (≥ 80 years). In contrast, ISR was approximately 0 for children (3 – 17 years). Among older adults, the ISR was significantly lower for the vaccinated (1.25%) than those who were non-vaccinated (4.77%). The sCFR was 0.96%, and the sCSR was 3.06%.

Conclusions

The infection rate during the latest outbreak in Shanghai was 2.74 per 100 individuals, and the rates of severe/critical disease and mortality were 6.34 and 2.42 per 100,000 individuals, respectively. Notably, the rates of severe/critical illness and mortality were significantly higher in the older population than in younger people. Most (> 90%) cases developed the asymptomatic disease during the outbreak. In summary, a low disease burden and severity reflected the success of strict containment measures.

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources

Journal references:

Article Revisions

  • May 13 2023 - The preprint preliminary research paper that this article was based upon was accepted for publication in a peer-reviewed Scientific Journal. This article was edited accordingly to include a link to the final peer-reviewed paper, now shown in the sources section.
Tarun Sai Lomte

Written by

Tarun Sai Lomte

Tarun is a writer based in Hyderabad, India. He has a Master’s degree in Biotechnology from the University of Hyderabad and is enthusiastic about scientific research. He enjoys reading research papers and literature reviews and is passionate about writing.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Sai Lomte, Tarun. (2023, May 13). The disease burden and clinical severity of the SARS-CoV-2 Omicron BA.2 sublineage outbreak in Shanghai. News-Medical. Retrieved on December 21, 2024 from https://www.news-medical.net/news/20220714/The-disease-burden-and-clinical-severity-of-the-SARS-CoV-2-Omicron-BA2-sublineage-outbreak-in-Shanghai.aspx.

  • MLA

    Sai Lomte, Tarun. "The disease burden and clinical severity of the SARS-CoV-2 Omicron BA.2 sublineage outbreak in Shanghai". News-Medical. 21 December 2024. <https://www.news-medical.net/news/20220714/The-disease-burden-and-clinical-severity-of-the-SARS-CoV-2-Omicron-BA2-sublineage-outbreak-in-Shanghai.aspx>.

  • Chicago

    Sai Lomte, Tarun. "The disease burden and clinical severity of the SARS-CoV-2 Omicron BA.2 sublineage outbreak in Shanghai". News-Medical. https://www.news-medical.net/news/20220714/The-disease-burden-and-clinical-severity-of-the-SARS-CoV-2-Omicron-BA2-sublineage-outbreak-in-Shanghai.aspx. (accessed December 21, 2024).

  • Harvard

    Sai Lomte, Tarun. 2023. The disease burden and clinical severity of the SARS-CoV-2 Omicron BA.2 sublineage outbreak in Shanghai. News-Medical, viewed 21 December 2024, https://www.news-medical.net/news/20220714/The-disease-burden-and-clinical-severity-of-the-SARS-CoV-2-Omicron-BA2-sublineage-outbreak-in-Shanghai.aspx.

Comments

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment
Post

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Depression and anxiety diagnoses in youth spiked during the COVID-19 pandemic