Long COVID’s significant impact on health calls for greater consideration in pandemic policy planning

In a recent study published in the International Journal of Epidemiology, the researchers presented a comprehensive approach to estimate the morbidity associated with long-lasting coronavirus disease (COVID) in the Australian population.

The approach analyzed the period during which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dominated the Omicron variant of concern (VOC) between 2021 and 2022.

Study: The health impact of long COVID during the 2021-2022 Omicron wave in Australia: a quantitative study of disease burden. Image Credit: tilialucida/Shutterstock.com

Background

Post-COVID-19 (CCP) or long status covid symptoms occur in a considerable proportion of individuals following acute COVID 2019 (COVID-19), less frequently in vaccinated individuals in the post-acute phase of Omicron VOC infections than Delta VOC infections.

Given the continued increase in SARS-CoV-2 transmission around the world, it is essential to quantitatively assess the burden of COVID-19 and the associated long-term consequences.

Previous estimates of PCC associated with pre-Omicron VOCs have been reported analyzing only primary symptoms, lacking adequate control groups, and therefore failing to recognize the true extent and heterogeneity of PCC symptomatology.

The paucity of high-quality data on CCP symptoms prevents quantifying the global burden of CCP is clear. Additionally, most of the long COVID studies included unvaccinated individuals infected during the pre-Omicron COV period.

About the study

In the present study, researchers provided comprehensive estimates of the long morbidity associated with COVID, by analyzing individual CCP symptoms experienced during Omicron’s dominance in Australia.

To accurately quantify the effects of CCP in COVID-19 vaccinates during Omicron dominance, differences in CCP risks by COVID-19 vaccination status and SARS-CoV-2 VOCs were assessed.

PCC-associated morbidity resulting from Omicron infections was estimated by assessing the onset, severity, and duration of each PCC symptom. CCP-related years lived with disability (YLD) during Omicron BA.1 and BA.2 prevalence were calculated by evaluating data from previous cross-sectional, cohort, and case-control studies, determining the duration and the prevalence of each PCC symptom.

Predicted health losses were compared to those associated with acute COVID-19-associated years lived with disability and years of life lost (YLL) due to SARS-CoV-2 infections.

Total components yielded disability-adjusted life years (DALYs) associated with COVID-19, compared to DALYs associated with other diseases reported in the 2019 Global Burden of Disease (GBD) study .

The team quantified the severity of symptoms of long COVID as a disability weight (DW), reported in the Global Burden of Disease study. Baseline case prevalence estimates for unvaccinated and pre-infected with Omicron COV were multiplied by an odds ratio (OR) of 0.6 to assess the prevalence of long COVID symptoms among COVID-19 vaccinated .

Prevalence estimates were multiplied by OR 0.3, based on an estimate of reductions in prevalence of any COVID symptom long ≥ 4.0 weeks after Omicron VOC infection compared to Delta VOC infection among COVID-19 vaccinees residing in the UK.

PCC YLDs were calculated as the estimated PCC-associated morbidity for each symptomatic infection multiplied by the number of symptomatic BA.1 and BA.2 infections between December 10, 2021 and April 9, 2022.

Data on nationwide COVID-19 vaccinations and duration of symptoms for hospitalized patients were obtained from a New South Wales (NSW)-based study.

The team performed sensitivity analyzes by varying the prevalence rates of physical, cognitive and psychological symptoms. Additionally, an extreme case scenario was analyzed by applying the odds ratio for SARS-CoV-2 Omicron VOC infections versus pre-Omicron VOC infections (OR 0.3) to hospitalized patients.

Results

In Australia, five million SARS-CoV-2 infections have been documented in the first four months of Omicron prevalence, with 35,500 and 3,463 hospitalizations and deaths respectively, and predicted that 61% of those infected were vaccinated against COVID-19.

A total of 5,200 YLDs and 1,800 YLDs were attributed to PCC and acute COVID-19, respectively, indicating that PCC caused 74.0% of COVID-19-associated YLDs during BA.1 dominance and BA.2.

50,900 DALYs were attributed to SARS-CoV-2, representing 2% of expected DALYs for all diseases during the period, and CCP contributed 10%. This was compared to the 3.6% DALYs resulting from acute morbidity associated with SARS-CoV-2 infection and the remaining DALYs from acute mortality associated with SARS-CoV-2 infection.

The team obtained most YLD PCCs from community-based cases, the majority of which were seen in vaccinated adults (2,200 YLD), given that the group accounted for 51% of documented long COVID cases.

Morbidity associated with COVID-19 showed a comparable extent of non-fatal health losses associated with chronic kidney disease and myocardial ischemia. COVID-19 was listed in Australia’s top ten reasons for DALYs during the study period. For COVID-19 vaccinated adults not requiring hospitalization during the acute phase of COVID-19, 0.10% of a healthy life year was estimated to be lost due to CCP ( or 33% of a day of healthy life lost).

Sensitivity analyzes reduced overall PCC morbidity by 12.0% compared to the primary analysis, at 4,600 YLD. The estimated PCC morbidity was within 20% of the Institute for Health Metrics and Evaluation (IHME) estimate, indicating that the present study approach was valid.

conclusion

Overall, the study results highlighted the effects of CCP in Australians, assessed using the type of disease burden approach, providing a more accurate estimate of the burden of CCP than that reported in previous studies.

CCP contributed to 74.0% of non-fatal health losses, resulting from BA.1 and BA.2 infections documented in Australia. Increasing data on PCC symptoms would improve the accuracy of study results.

Additionally, the prevalence of PCC symptoms is lower for Omicron infections and in COVID-19 vaccinates than pre-Omicron infections in unvaccinated individuals.

However, PCC contributes considerable health loss regardless of vaccine protection when summarizing infection estimates. Thus, CCP must be considered when formulating COVID-19 mitigation policies and strategies.