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. 2024 Oct 11;19(10):e0311287.
doi: 10.1371/journal.pone.0311287. eCollection 2024.

Spectrum of COVID-19 cases in Arkhangelsk, Northwest Russia: Findings from a population-based study linking serosurvey, registry data, and self-reports of symptoms

Ekaterina Krieger  1   2 , Alexander V Kudryavtsev  2 , Ekaterina Sharashova  1 , Olga Samodova  3 , Anna Kontsevaya  4 , Vitaly A Postoev  5
Affiliations

Spectrum of COVID-19 cases in Arkhangelsk, Northwest Russia: Findings from a population-based study linking serosurvey, registry data, and self-reports of symptoms

Ekaterina Krieger et al. PLoS One. .

Abstract

Introduction: The spectrum of COVID-19 manifestations makes it challenging to estimate the exact proportion of people who had the infection in a population, with the proportion of asymptomatic cases likely being underestimated. We aimed to assess and describe the spectrum of COVID-19 cases in a sample of adult population aged 40-74 years in Arkhangelsk, Northwest Russia, a year after the start of the pandemic.

Materials and methods: A population-based survey conducted between February 24, 2021 and June 30, 2021 with an unvaccinated sample aged 40-74 years (N = 1089) combined a serological survey data, national COVID-19 case registry, and self-reported data on COVID-19 experience and symptoms. Based on the agreement between these sources, we classified the study participants as non-infected and previously infected (asymptomatic, non-hospitalized and hospitalized symptomatic) cases, and compared these groups regarding demographics, lifestyle and health characteristics.

Results: After a year of the pandemic in Arkhangelsk, 59.7% 95% confidence intervals (CI) (56.7; 62.6) of the surveyed population had had COVID-19. Among those who had been infected, symptomatic cases comprised 47.1% 95% CI (43.2; 51.0), with 8.6% 95% CI (6.6; 11.1) of them having been hospitalized. Of the asymptomatic cases, 96.2% were not captured by the healthcare system. Older age was positively associated, while smoking showed a negative association with symptomatic COVID-19. Individuals older than 65 years, and those with poor self-rated health were more likely to be hospitalized.

Conclusion: More than half of the infected individuals were not captured by the healthcare-based registry, mainly those with asymptomatic infections. COVID-19 severity was positively associated with older age and poor self-rated health, and inversely associated with smoking. Combining different sources of surveillance data could reduce the number of unidentified asymptomatic cases and enhance surveillance for emerging infections.

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Conflict of interest statement

the authors report there are no competing interests to declare

Figures

Fig 1
Fig 1. Flow chart of the study.
Fig 2
Fig 2. Classification of the study participants based on the linkage of the serosurvey, the COVID-19 case registry data and the self-reported survey data, N = 1089.
Fig 3
Fig 3. Distribution of the symptomatic cases over time.
Fig 4
Fig 4. Symptoms self-reported by the non-hospitalized and hospitalized symptomatic patients, N = 306.
p for Pearson’s Chi-squared test.
See this image and copyright information in PMC

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