The health impact of long COVID during the 2021-2022 Omicron wave in Australia: a quantitative burden of disease study

Abstract

Background: Long COVID symptoms occur for a proportion of acute COVID-19 survivors, with reduced risk among the vaccinated and for Omicron compared with Delta variant infections. The health loss attributed to pre-Omicron long COVID has previously been estimated using only a few major symptoms.

Methods: The years lived with disability (YLDs) due to long COVID in Australia during the 2021-22 Omicron BA.1/BA.2 wave were calculated using inputs from previously published case-control, cross-sectional or cohort studies examining the prevalence and duration of individual long COVID symptoms. This estimated health loss was compared with acute SARS-CoV-2 infection YLDs and years of life lost (YLLs) from SARS-CoV-2. The sum of these three components equals COVID-19 disability-adjusted life years (DALYs); this was compared with DALYs from other diseases.

Results: A total of 5200 [95% uncertainty interval (UI) 2200-8300] YLDs were attributable to long COVID and 1800 (95% UI 1100-2600) to acute SARS-CoV-2 infection, suggesting long COVID caused 74% of the overall YLDs from SARS-CoV-2 infections in the BA.1/BA.2 wave. Total DALYs attributable to SARS-CoV-2 were 50 900 (95% UI 21 000-80 900), 2.4% of expected DALYs for all diseases in the same period.

Conclusion: This study provides a comprehensive approach to estimating the morbidity due to long COVID. Improved data on long COVID symptoms will improve the accuracy of these estimates. As data accumulate on SARS-CoV-2 infection sequelae (e.g. increased cardiovascular disease rates), total health loss is likely to be higher than estimated in this study. Nevertheless, this study demonstrates that long COVID requires consideration in pandemic policy planning, given it is responsible for the majority of direct SARS-CoV-2 morbidity, including during an Omicron wave in a highly vaccinated population.

Keywords: COVID-19; burden of disease; epidemiology; long COVID.

Figure 1

Flow diagram—prevalence cross-walk method. OR = 0.25 indicates reduced odds of long COVID among Omicron-infected cases compared with Delta-infections—applied to not hospitalized (i.e. community) adult cases and children. OR = 0.55 indicates reduced odds of long COVD among vaccinated (at least two COVID-19 vaccines) compared with unvaccinated (less than two vaccines) cases—applied to all vaccinated subgroups

Figure 2

COVID-19 YLDs resulting directly from Omicron cases during the first 4 months of the Omicron wave, 10 December 2021 to 9 April 2022; 95% uncertainty intervals are shown for long COVID YLD estimates, measured with +/-30% standard deviation. Total morbidity is estimated at 7000 YLDs. YLDs, years lived with disability

Figure 3

Burden of disease comparison during the first 4 months of the Omicron wave (10 December 2021 to 9 April 2022), Australia. Panel A. Comparison of the YLDs due to COVID-19, separated as long COVID and acute COVID-19, with other outcomes. Total COVID-19 YLDs = 7000 (95% uncertainty interval 2900-11 200). Panel B. Comparison of the DALYs due to COVID-19, separated as long COVID and acute COVID-19, with other outcomes. Total COVID-19 DALYs = 50 900 (95% uncertainty interval 21 000-80 900). Note that COVID-19 YLDs and DALYs include the future morbidity resulting from long COVID for these cases; 95% uncertainty intervals are shown for COVID-19 DALY and YLD estimates (+/-30% standard deviation). YLDs and DALYs for other outcomes are estimated from the 2019 GBD study, updated to the population size as of June 2021, and subsequently divided by three to estimate health loss over a 4-month period. COPD, chronic obstructive pulmonary disease; CKD, chronic kidney disease; T2DM, type 2 diabetes mellitus; YLD, years lived with disability; GBD, Global Burden of Disease; DALYs, disability-adjusted life-years. *Total COVID-19 YLDS/DALYS include acute COVID-19 and long COVID