COVID-19 and Respiratory Virus Co-Infections: A Systematic Review of the Literature

Abstract

Τhe COVID-19 pandemic highly impacted the circulation, seasonality, and morbidity burden of several respiratory viruses. We reviewed published cases of SARS-CoV-2 and respiratory virus co-infections as of 12 April 2022. SARS-CoV-2 and influenza co-infections were reported almost exclusively during the first pandemic wave. It is possible that the overall incidence of SARS-CoV-2 co-infections is higher because of the paucity of co-testing for respiratory viruses during the first pandemic waves when mild cases might have been missed. Animal models indicate severe lung pathology and high fatality; nevertheless, the available literature is largely inconclusive regarding the clinical course and prognosis of co-infected patients. Animal models also indicate the importance of considering the sequence timing of each respiratory virus infection; however, there is no such information in reported human cases. Given the differences between 2020 and 2023 in terms of epidemiology and availability of vaccines and specific treatment against COVID-19, it is rational not to extrapolate these early findings to present times. It is expected that the characteristics of SARS-CoV-2 and respiratory virus co-infections will evolve in the upcoming seasons. Multiplex real-time PCR-based assays have been developed in the past two years and should be used to increase diagnostic and infection control capacity, and also for surveillance purposes. Given that COVID-19 and influenza share the same high-risk groups, it is essential that the latter get vaccinated against both viruses. Further studies are needed to elucidate how SARS-CoV-2 and respiratory virus co-infections will be shaped in the upcoming years, in terms of impact and prognosis.

Syndromic surveillance of population-level COVID-19 burden with cough monitoring in a hospital emergency waiting room

“…We can see high correlation coefficients between daily positive COVID patient count and the number of patients with positive RSV (0.38 with a p -value of 0.0003). This could be because the viruses peaked in the community around the same time and because people were co-infected ( 39 , 40 ). Additionally, we can see that the number of people, and the number of positive COVID patients has a correlation coefficient of 0.22.…”

Viral coinfection in hospitalized patients during the COVID-19 pandemic in Southern Brazil: a retrospective cohort study

“…Studies reported that mortality is associated with ICU and even more so with nosocomial infection [ 19 , 20 ]. Many cases require hospitalization, and with preexisting diseases, the patients have a greater possibility of coinfections, mainly RSV and FLUAV [ 14 , 21 , 22 ]. Similar studies showed an increased risk of death associated with coinfection [ 6 ].…”

“…The prevalence of SARS-CoV-2 and other respiratory viruses varied throughout the COVID-19 pandemic waves with declines in FLUAV and FLUBV, RSV, HRV, and EV infections, which are the most commonly described [ 6 , 17 , 23 ]. Other viruses such as HAdV, HPIV, and hMPV were less detected compared to previous years, even during the winter season when these viruses commonly present higher rates of detection [ 17 , 22 , 24 ]. HRV was the main pathogen to substantially cocirculate with SARS-CoV-2 during the pandemic period and remains present at a considerable rate (~ 20%) [ 5 , 17 , 25 , 26 ].…”

The state of COVID-19 in Greece: Vigilance in the face of unpredictability

“…As testing rules have eased or completely relaxed, asymptomatic patients or patients with symptoms that have not been tested or confirmed with COVID-19, can challenge the transmission of the virus amongst the most vulnerable. Moreover, the overall impact of respiratory virus co-infections in the present and upcoming seasons remains highly unknown in terms of morbidity burden, clinical severity, and outcome 8 . Though widespread testing of symptomatic individuals cannot be enforced nor justified, agreeing on a reasonable testing protocol for all respiratory viruses would make sense, especially within hospitals, so that we can identify coinfections and optimize treatment for patients.…”