First what is Interferon (IFN)? There are three types of IFN. This post will focus on the IFN that the body typically makes when it encounters a virus. This is known as type I IFN. Yes, thankfully cells that are infected with virus start to make IFN and the IFN then seeks out uninfected cells to protect the body from the virus. But there is a battle. If the body cannot make enough IFN, then the virus might overwhelm this natural defense mechanism. But, we have lots of natural defense mechanisms. For example, the IFN also recruit Natural Killer or NK cells which are a type of white blood cell that can kill the infected cells.
Non-controlled studies have shown earlier resolution of fever and clearance of infectious virus with treatment of type I interferon (Int. Immunopharm Aug, 2020). In another Chinese non-controlled study, virus was cleared more quickly from COVID-19 patients with severe respiratory disease treated with IFN or an antiviral (arbidol, a drug used in China to treat influenza), (Front. Immunol, May 15, 2020).
A recent analysis of several studies showed that treatment of SARS (not COVID-19) infected patients in the late stages of disease might have benefited by the addition of IFN (Internat. Immunopath. Jun 25, 2020). This suggests that IFN treatment might be of benefit to patients earlier in the course of infection if defects in their ability to produce IFN can be identified.
Today, an important finding was reported in Science (Hadjadj, J, et al, July 13, 2020). An impaired type I IFN response was found in severely ill COVID-19 infected patients. Levels of IFN in blood were lower in severely ill patients in comparison to moderately ill patients. When multiple measures of IFN were taken in a few patients over time they did show consistency.
This sounds like all we need to do is give IFN to patients with COVID-19 severe respiratory disease and the problem is solved. BUT, hold on….here is the hitch. IFN and lots of immune system function come with a double edged sword. It all depends on timing. Severe COVID-19 disease is caused by an uncontrolled inflammatory response in the lungs. The immune system puts out proteins that call in immune cells that inflame the area. And, type I IFN is also part of that insult. SO, can we really add more type I IFN to that insult?? Probably not in severe, late disease patients but IFN might by an arrow in the quiver for earlier stage patients. Clinical studies are now ongoing.