Prevention at Full Steam ‐ Can Steam Inhalation Stop the Contagion of Sars‐Cov 2?

Covid‐19 vaccination and social barrier efforts worldwide have deescalated the death and morbidity toll due to Sars CoV‐2 infection in most countries. However, intramuscular vaccination leads to a variable antibody response insufficient to provide airway mucosal immunity that prevents contagion and reinfection in asymptomatic carriers. Nasal vaccines could provide this missing piece and are currently being tested with encouraging results, but large‐scale availability and efficacy in humans are unknown. Moreover, previous exposure to the virus would render nasal spray vaccines less effective. Past literature on upper airway infections has shown that water steam inhalation therapy (WSIT) may modulate airway mucosa immunity responses. Airway mucosal immunity in COVID‐19 infection is a critical aspect to consider with WSIT. Based on a small but slowly growing body of evidence, we propose that WSIT may be a relevant home remedy worth revisiting to help halt mass contagion. Here, we review current and past studies on WSIT use in upper respiratory infections (URI). Previous studies reported mixed results on the efficacy of steam therapy on viral respiratory diseases. Safety concerns with steam therapy include possible nosocomial infections associated and burns. There is a paucity of studies with high methodological quality exploring the outcomes of this ancient therapy. Upper airway blood flow increases substantially after 15‐min of steam inhalation with temperatures of 42 ℃. Still, methods to measure bronchial blood flow are lacking, and this may be an essential variable for the analysis of how steam may impact mucosal immune responses. Studies with better methodologies demonstrate that nebulized steam at 80°C for 20 min reduces neutrophils compared to controls in COPD patients indicating an anti‐inflammatory effect. The best evidence for using WSIT for upper airway viral disease shows that 60% of asymptomatic carriers increased viral shedding immediately post steam inhalation, and Rt‐PCR testing confirmed viral negativity at 10‐days post‐treatment. Subjects used steam for a total of 20 minutes per hour with steam temperatures ranging from 55 to 65℃. Efficacy rates decline with research methodologies that use WSIT for less than 20 minutes. In summary, more recent studies using WSIT for URI show encouraging results and may help to disentangle former controversies. Lessons emerging from previous studies indicate that exposure of WSIT less than 20 minutes may be ineffective. Adopting WSIT as an inexpensive public health measure may lead to secondary prevention of airway viral infections, especially in new viral strands that have the potential to become pandemic.