Respiratory viruses: their importance and lessons learned from COVID-19

Abstract

Respiratory virus infection can cause severe illnesses capable of inducing acute respiratory failure that can progress rapidly to acute respiratory distress syndrome (ARDS). ARDS is related to poor outcomes, especially in individuals with a higher risk of infection, such as the elderly and those with comorbidities, i.e. obesity, asthma, diabetes mellitus and chronic respiratory or cardiovascular disease. Despite this, effective antiviral treatments available for severe viral lung infections are scarce. The coronavirus disease 2019 (COVID-19) pandemic demonstrated that there is also a need to understand the role of airborne transmission of respiratory viruses. Robust evidence supporting this exists, but better comprehension could help implement adequate measures to mitigate respiratory viral infections. In severe viral lung infections, early diagnosis, risk stratification and prognosis are essential in managing patients. Biomarkers can provide reliable, timely and accessible information possibly helpful for clinicians in managing severe lung viral infections. Although respiratory viruses highly impact global health, more research is needed to improve care and prognosis of severe lung viral infections. In this review, we discuss the epidemiology, diagnosis, clinical characteristics, management and prognosis of patients with severe infections due to respiratory viruses.

FIGURE 1

Coronavirus disease 2019 (COVID-19) spectrum. COVID-19 has various clinical manifestations, with the spectrum of the disease ranging from asymptomatic to critical illness. Managing patients with COVID-19 will depend on disease severity. Patients with risk factors for severe disease and those with moderate disease should be monitored closely. The presence of respiratory rate ≥30 breaths per minute, oxygen saturation <94%; arterial oxygen tension (P_aO2)/inspiratory oxygen fraction (F_IO2) <300 mmHg and lung infiltrates >50% are indicators of severe disease. Critical illness is related to respiratory failure, septic shock and/or multiple organ dysfunction. Viral replication is higher before or soon after symptom onset. Inflammation presents later in the disease. S_pO2: oxygen saturation measured by pulse oximetry, peripheral oxygen saturation. Information from [2, 3, 132].

FIGURE 2

Evolution of the coronavirus disease 2019 (COVID-19) pandemic. The first cases of unknown pneumonia were reported in Wuhan, China in December 2019. Over the following 2 years, more than 504 million cases were confirmed worldwide, including 6.2 million deaths. FDA: Food and Drug Administration; IDSA: Infectious Diseases Society of America; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; WHO: World Health Organization.

FIGURE 3

Airborne transmission of respiratory viruses. Data about the incubation period for various respiratory viruses and their basic reproduction number (R₀).