#16,164
The lack of influenza circulation since the spring of 2020 means that we have fairly limited data on coinfections with COVID-19 and seasonal flu. We've seen a few early reports (see April 2020's IDCases: Co-infection With SARS-CoV-2), but the sampling size was too small to gauge the impact, other than to establish that co-infection with other respiratory viruses (influenza, parainfluenza, etc.) was possible.
In September of 2020, we saw a preprint from the UK's PHE (see PHE Study: Co-Infection With COVID-19 & Seasonal Influenza) that found - among a small cohort (n=58) unlucky enough to be coinfected with SARS-CoV-2 and Flu - the risk of severe illness and/or death appears to increase substantially.
While contracting influenza appears to reduce your odds of being infected with COVID (likely due to `viral interference' ), the authors found that when it does occur:
Patients with a coinfection had a risk of death of 5.92 (95% CI, 3.21-10.91) times greater than among those with neither influenza nor SARS-CoV-2 suggesting possible synergistic effects in coinfected individuals.
Due to the timing of these early reports, they almost certainly dealt with the 2020 `wild-type' COVID, and not the more recently emerged, and more aggressive, Alpha or Delta variants.
Further complicating matters, one of the few proven therapeutics for COVID patients sick enough to be hospitalized is dexamethasone (a powerful steroid) whose use is highly controversial - and generally discouraged - in influenza pneumonia cases.
So far influenza activity remains limited around the world, but there are growing concerns it may return this fall and winter (see UK Academy Of Medical Sciences: Looking Ahead To COVID-19 Over Winter 2021/22 & Beyond), which would not only complicate the pandemic response, but also increase the chances of seeing COVID-Influenza coinfections.
All of which brings us to a case series, published last week in the journal Cureus, which details 5 coinfected patient's treatment and outcome. Of greatest interest to clinicians, this study explores the challenges of treating two different disease processes, when the preferred treatment for one is not optimal for the other.
I've only posted some excerpts, so follow the link to read the full study. I'll have a postscript when you return.
A Case Series of SARS-CoV-2 and Influenza Co-infection
Ruhma Ali, Aditya Patel, Kok Hoe Chan, Sindhusha Veeraballi, Jihad Slim
Published: August 31, 2021 (see history)
DOI: 10.7759/cureus.17597
Cite this article as: Ali R, Patel A, Chan K, et al. (August 31, 2021) A Case Series of SARS-CoV-2 and Influenza Co-infection. Cureus 13(8): e17597. doi:10.7759/cureus.17597
Abstract
The novel coronavirus 2019, a disease associated with SARS-CoV-2 infections has resulted in significant morbidity and mortality across the globe. In the United States, influenza has been one of the leading causes of hospitalization during the winter season. To date, the co-infection of SARS-CoV-2 and influenza virus has created a unique challenge for healthcare workers, especially during the cold season. Both viruses have similar clinical presentation and transmission characteristics. Many reports are available for either SARS-CoV-2 and influenza individual infections, but limited data are available for the co-infection. Herein, we present a case series of five cases of SARS-CoV-2 and influenza co-infection as well as their clinical characteristics, laboratory findings, management, and outcome.
Introduction
The 2019 novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) has affected 188,655,968 worldwide with over 4,067,517 deaths till July 2021 [1]. Current evidence suggests that the causative agent of coronavirus 2019 (COVID-19) is primarily transmitted through contact and respiratory droplets similar to the influenza virus. The clinical presentation of COVID-19 is also similar to the influenza virus. Influenza has been known to cause infection with other respiratory pathogens [2]. However, limited data is available on the morbidity and mortality of patients with COVID-19 and influenza co-infection. In this case series, we presented five patients who were admitted with COVID-19 and influenza co-infections as well as their clinical outcome and treatment plan.
(SNIP Case Details)
Discussion (excerpt)
Co-infection with COVID-19 and influenza virus have been reported in different parts of the world with single cases seen in Taiwan, Brazil, Japan, Germany, and Spain at the start of the pandemic. Four cases were observed in Iran [5], five patients among 115 in Wuhan had coinfection with COVID-19 and influenza [6], six patients among 1103 in Turkey [2], and 23 cases among 105 in Northeastern Iran [7]. The clinical characteristics of patients with both COVID-19 and influenza were similar to those with COVID-19 alone. The symptoms of COVID-19 take longer to occur and the person is contagious for a longer duration. Testing is required to differentiate between the two respiratory pathogens as per Infectious Diseases Society of America (IDSA) guidelines [6]. The main complications reported were ARDS (20% of the patients), acute kidney damage, and acute liver failure (60% of the patients) [7]. In our case, ARDS was the major complication seen in one patient.
Guidelines regarding the treatment of COVID-19 are constantly evolving. Corticosteroid therapy has been shown to be effective in moderate to severe cases of COVID-19, however, it can be harmful to patients with influenza [8]. A recent preliminary report found that dexamethasone resulted in lower 28-day mortality among patients with COVID-19 respiratory support. The effect of corticosteroids on patients with pneumonia remains controversial and is restricted in the setting of clinical trials so far [9]. Several observational studies have failed to demonstrate any beneficial effects of steroid use for patients with influenza pneumonia. Further randomized controlled trials are required to support this hypothesis. Patients with influenza are usually treated with oseltamivir. Patients with co-infection should be treated with oseltamivir and standard of care of COVID-19.
Conclusions
Both influenza and COVID-19 can have similar presentations. It is important to recognize the co-infection since the management and prognosis will be different. Glucocorticoids should be used with caution in patients with positive influenza virus due to the negative effects of steroids on the morbidity and mortality of these patients. Nonetheless, for patients with influenza and COVID-19, they should be treated with antiviral for influenza (oseltamivir) and COVID-19 (remdesivir) with cautions use of dexamethasone.
We've already seen a sharp rise in RSV cases over the summer, likely propelled by the decline in social distancing and face mask use since May. Assuming those societal trends continue, the return of winter respiratory infections (Influenza, RSV, Rhinoviruses, Adenoviruses, etc.) seems likely.
Right now, we don't know how common coinfections with COVID and Influenza (and other respiratory viruses) are likely to be.
A 2020 study (LINK) from China that looked at 78 COVID cases identified 11 coinfections (14.1%), with Mycoplasma pneumoniae (n=5, 45.5%) and RSV (n=4, 36.4%) being the most common, but how that translates to today, and in other regions, is unknown.
All of which means that if winter respiratory viruses finally do return - and if they circulate alongside COVID - we could find ourselves entering an entirely new, and potentially more challenging, stage of this pandemic.
