Prevalence of long COVID-19 after Omicron infection

A recent article posted to the medRxiv* preprint server analyzed the long coronavirus disease (COVID) linked with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant. 

Study: Post COVID-19 condition of the Omicron variant of SARS-CoV-2. Image Credit: Donkeyworx / Shutterstock

Study: Post COVID-19 condition of the Omicron variant of SARS-CoV-2. Image Credit: Donkeyworx / Shutterstock

Background

The ongoing COVID 2019 (COVID-19) pandemic has led to over 525 million confirmed-SARS-CoV-2 infections and 6.28 million deaths globally. According to available data, roughly half of COVID-19 patients experienced at least one long-term symptom continuing more than a year after the infection. Long COVID, also called the post-COVID-19 condition, is a post-acute sequela of SARS-CoV-2 infection. The frequent symptoms of long COVID consisted of fatigue, dysosmia, and shortness of breath.

A prospective longitudinal observational study demonstrated that the proportion of acute-phase symptoms differed between individuals with SARS-CoV-2 Delta and Omicron infections. Sore throats were more prevalent in Omicron than Delta, whereas loss of smell was less frequent in Omicron versus Delta. Nevertheless, there have been no epidemiological reports of post-COVID-19 conditions caused by the SARS-CoV-2 Omicron variant.

About the study

The present cross-sectional, single-center study aimed to explore and compare the occurrence of the post-COVID-19 condition associated with the SARS-CoV-2 Omicron variant and other viral strains.

The authors conducted a telephonic interview for Japanese individuals who recovered from COVID-19-linked with Omicron (Omicron cohort) and assessed patients infected with other SARS-CoV-2 strains using self-reported questionnaires (control group). They collected written informed consent from subjects in the self-reported survey group and oral informed consent from the telephonic survey cohort. 

The frequency and duration of at least one symptom in the Omicron group and the control group after matching

The frequency and duration of at least one symptom in the Omicron group and the control group after matching

Patients admitted to the National Center for Global Health and Medicine (NCGM) with COVID-19 between 1 December 2021 and 9 February 2022 were requested to participate in telephonic interviews. These patients tested negative for the L452R mutation and positive for the E484A mutation of SARS-CoV-2, as determined by reverse transcription-polymerase chain reaction (rtPCR). Further, patients who died while in the hospital were not included in the research. COVID-19 convalescent individuals who visited the NCGM's outpatient facility of the Disease Control and Prevention Center from February 2020 to November 2021 were included in the control cohort.

The scientists gathered information on the patients' characteristics, the acute-phase SARS-CoV-2 infection, and the occurrence and duration of COVID-19-associated symptoms. A SARS-CoV-2-related symptom that persisted at least two months within three months of the initiation of COVID-19 was classified as a post-COVID-19 condition in this investigation. After completing propensity score matching, the team evaluated and compared the incidence of the long COVID-19 in both cohorts.

Results

The study results indicated that the authors interviewed 53 out of 128 patients with post-Omicron infection status and received 502 replies in the control cohort. Upon matching, 18 subjects in both the control and Omicron groups exhibited better covariate balance of the female sex, older adult, COVID-19 vaccination status, and obese patients. There were no notable variances in the prevalence of each post-acute SARS-CoV-2 symptom among the two cohorts. Besides, 5.6% and 55.6% of patients had a minimum of one post-acute COVID-19 symptom in the Omicron and control cohorts, respectively.

The team found that 28.3%, 84.9%, and 56.6% of Omicron patients experienced a runny nose, fever, and sore throat, respectively, yet none of these symptoms lasted more than two months within three months following the disease's beginning. They stated that describing the clinical course of Omicron infection was vital for public health since it informs the physicians and the public about the symptoms to monitor. It also helps them understand the possible impacts of potential SARS-CoV-2 variants of concern (VOCs).

Moreover, hair loss, dysosmia, and dysgeusia were seen in 3.8%, 5.7%, and 13.2% of individuals with Omicron infection, respectively. These findings can assist raise knowledge about which symptoms were more frequent with the Omicron mutant, allowing for rapid diagnosis and limiting COVID-19 spread.

Conclusion

To conclude, the study findings showed that the prevalence of long COVID did not differ significantly between the Omicron and control groups, albeit the post-Omicron COVID-19 conditions were less common than other SARS-CoV-2 strains. Furthermore, the Omicron group had a considerably lower number of patients with a minimum of one post-acute SARS-CoV-2 symptom than the control cohort.

The authors stated that although the prevalence rate in the Omicron group may be lower, the exact number of individuals experiencing the post-COVID-19 condition might be higher due to the vast number of persons infected with Omicron internationally. Hence, they suggested that more studies with a large sample size were required to explore the accurate epidemiology of the Omicron-linked long COVID condition and its influence on social productivity and health-associated quality of life. 

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
Shanet Susan Alex

Written by

Shanet Susan Alex

Shanet Susan Alex, a medical writer, based in Kerala, India, is a Doctor of Pharmacy graduate from Kerala University of Health Sciences. Her academic background is in clinical pharmacy and research, and she is passionate about medical writing. Shanet has published papers in the International Journal of Medical Science and Current Research (IJMSCR), the International Journal of Pharmacy (IJP), and the International Journal of Medical Science and Applied Research (IJMSAR). Apart from work, she enjoys listening to music and watching movies.

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Comments

  1. Nate Klingenstein Nate Klingenstein United States says:

    Please note that the control group(those presumed infected by other strains) and Omicron group differed dramatically.  Participation rates were low in both cohorts.  Information was gathered over the phone for one and through the mail for the other.  Absolute numbers of participants were low in both groups.  Many patients were already vaccinated before breakthrough Omicron infection, which reduces the incidence of long COVID.  I'll spare you more commentary.

    I also can't find Appendix 1, which is the questionnaire.

    This is of vital importance to the global economy, so I really, really hope this receives more study.

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