‘Long flu’ not as severe as long COVID but both need attention, experts say
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Key takeaways
- Infection with viruses like SARS-CoV-2 and influenza can have long-term health consequences.
- In a study, COVID-19 was linked to a 51% greater risk for death than influenza.
Similar to SARS-CoV-2, which can cause long COVID, people hospitalized with influenza are at an increased risk for health issues long after they have cleared the infection, according to a study.
“We and others have previously compared short-term outcomes of COVID-19 and influenza but no one had done a comparative analysis for long-term outcomes” Ziyad Al-Aly, MD, chief of research and development at VA Saint Louis Health Care System and clinical epidemiologist at Washington University in St. Louis, told Healio.
The new study “comparing the burden of health loss in the post-acute phase of influenza infection was inspired by our previous research on long COVID, which showed that the burden of health loss is higher in the post-acute phase of COVID-19 than the acute phase. We wanted to know if this also happens in influenza — and yes, it does,” Al-Aly said.
Other viruses are known to cause long-term health problems, including Ebola.
Although both SARS-CoV-2 and influenza can cause respiratory disease, their potential long-term effects are not the same. Whereas SARS-CoV-2 can attack a wide range of organ systems, influenza is “truly more of a respiratory virus,” according to Al-Aly, and poses more of a risk to the pulmonary system than COVID-19.
Al-Aly and colleagues analyzed data from the Department of Veterans Affairs on 81,280 people hospitalized with COVID-19 between March 1, 2020, and June 30, 2022, and 10,985 people admitted to the hospital with seasonal influenza between Oct. 1, 2015, and Feb. 28, 2019.
They followed study participants for up to 18 months to evaluate their risk for death, 94 individual health outcomes related to 10 organ systems, and admission and readmission to the ICU. The researchers then estimated the risk for adverse events and disability-adjusted life-years (DALYs) per 100 persons.
During the 18 months of follow-up, the COVID-19 group had a 51% greater risk for death (HR = 1.51; 95% CI, 1.45-1.58) than people in the influenza group, with an excess death rate of 8.62 (95% CI, 7.55-9.44) per 100 persons in the COVID-19 group compared with the influenza group, according to the study.
Comparative analyses of the 94 individual health outcomes showed that patients with COVID-19 had an increased risk for 68.1% (64 of 94) of the outcomes compared with 6.4% (six of 94) for people with influenza.
The researchers found that COVID-19 posed a higher risk to nine of 10 organ systems compared with influenza, the exception being the pulmonary system. The cumulative rates of adverse health outcomes across all organ systems also was greater for people with COVID-19 at 615.18 (95% CI, 605.17-624.88) compared with influenza, at 536.90 (95% CI, 527.38-544.90). Additionally, DALYs were 45.03 higher among patients with COVID-19 than people with influenza.
Although the study showed that COVID-19 poses a greater risk to health than influenza, and a greater risk for long-term symptoms in both the acute and post-acute phases, the researchers determined that both carried a higher burden of health loss in the post-acute phase than during the acute phase.
“Before the pandemic, far too many people trivialized acute viral infections as inconsequential,” Al-Aly said. “This pandemic has taught us otherwise. Acute viral infections can have serious and sometimes debilitating long-term consequences.
“This will help us understand long COVID, other infection-associated chronic illnesses and also help us be better prepared for the next pandemic. Wasting this historic opportunity to learn would be a colossal and tragic mistake.”
Al-Aly said that, based on the study, “long COVID is much more of a health problem than COVID-19, and long flu is much more of a health problem than influenza,” which reveals what he calls a “vastly under-recognized” lesson of the COVID-19 pandemic.
“We don’t know why some infectious agents — which can include bacteria in some cases — may also cause chronic illnesses,” he said. “We need to study this more to develop a deeper understanding of why and how some acute infectious agents cause chronic diseases. This should be a major area of investigation and should be prioritized by governments and funding agencies.”
References:
- Al-Aly Z, et al. Lancet Infect Dis. 2023;doi:10.1016/S1473-3099(23)00762-4.
- ‘Long flu’ has emerged as a consequence similar to long COVID. https://medicine.wustl.edu/news/long-flu-has-emerged-as-a-consequence-similar-to-long-covid-19/. Published Dec. 14, 2023. Accessed Dec. 18, 2023.
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