Treating the host.

One of the key values of therapeutics is their potential in stabilizing patients prior to subsequent interventions or their use as adjuncts to those interventions. The settings where this may occur are varied and include response to traumatic injury to control damage, treat infection and alleviate pain. Other notable examples include the development of anaesthesiology and sedation to enable the performance of surgery and complex procedures, as well the development of non-depolarising neuromuscular-blocking drugs as adjuncts to those surgical procedures and of adjunctive chemotherapy to improve quality of life and survival time. Of particular interest in this pandemic context has been the centuries old development of agents to promote survival with infections. Historically the focus was upon identifying agents that would kill the invading species and not damage the host. In more recent times the focus has moved to delineating the treatment of the host from treatment and elimination of the infective agent.
In 2016, Fedson highlighted the treating of the host concept, based upon an understanding that a beneficial clinical phenotype has been observed with a treatment and this can be employed for the purpose of treating the host (3). This was done in the context of emerging virus diseases, and more recently in the context of severe COVID-19 infection (5). Consistent with this view Yan et al. (6) drew attention to the need for agents to alleviate H5N1 virus-induced lung injury due to the limited strategies for treating influenza virus infection.
The concept of treating the host is entirely complementary to opportunities arising in the area of drug repurposing that we have highlighted recently (7). In the case of COVID-19 disease this would mean identifying drugs that are focused, not on the elimination of the virus, but upon the survival of the patient with severe COVID-19 disease. This includes drugs approved for other indications that have the beneficial phenotype for treating severe COVID-19 disease. The fundamental advantages of this approach are; firstly, to buy needed time for the concurrent development of anti-viral or vaccines, secondly to provide health authorities a treatment insurance as they begin to release the public from social isolation. We have highlighted this key aspect recently in the context of Covid-19 disease (8). However this very obvious but distinct suite of solutions to reduce the morbidity and mortality from COVID has the potential risk of cutting across fixed interests and previously effective methods of succeeding in grant funding rounds, including silos of ‘ology disciplines, and pressures from news cycles and campaigning for ineffective policies.
What is needed is the appropriate framework for treating the host, a strategy for positioning this approach, and then implementation.