PCR, IgM and IgG tests answer different questions. PCR detects viral genetic material and shows whether virus is present now. IgM antibodies rise early in an immune response. IgG antibodies rise later and persist, marking past exposure.
These notes date from 2020 and are retained as written. They reflect the information available at the time and are not current clinical guidance.
Does metabolic health change how a virus affects you?
Everyone is eventually exposed. A virus has no morals and no politics. It expresses itself according to the host’s biochemical capacity. That framing was the reason for arguing, in 2020, that metabolic health was a modifiable determinant of outcome (something you can change that shapes how you fare). It was not an irrelevance during an acute crisis.
Fewer than 12.2% of US adults were metabolically healthy in 2009–2016, and fewer than 7% are today. So the size of the susceptible population was not a marginal concern.
What is the difference between PCR, IgM and IgG tests?
PCR detects viral genetic material and answers whether virus is present now. IgM antibodies rise early in an immune response. IgG antibodies rise later and persist, which points to past exposure. They answer different questions. Using one to answer another’s question produced much of the confusion of that period.
Why did hospital workers face higher exposure?
An observation from anesthesia practice: hospital workers may have faced higher exposure partly because ICU ventilators are open-loop systems, unlike the closed-loop circuits used in anesthesia. The distinction is about where exhaled gas goes.
Why it is kept
This is archived rather than removed because the underlying argument — that host metabolic capacity shapes the expression of an infectious exposure — did not depend on the specifics of that virus. It has held up better than most of what was said at the time.
Frequently asked questions
What does a PCR test show?
A PCR test detects viral genetic material. It answers one question: is the virus present right now? It does not tell you whether you were exposed in the past. Antibody tests answer that different question. Much of the confusion in 2020 came from using one kind of test to answer the other one’s question.
What does an IgM antibody test tell you?
IgM antibodies are the early responders. They rise early in an immune response, so an IgM result speaks to the early phase of the body’s reaction to an exposure. That is a different measurement from PCR, which looks for the virus itself, and from IgG, which rises later and persists. Read each test for the question it was built to answer.
What does a positive IgG antibody test mean?
IgG antibodies rise later in an immune response than IgM, and they persist. That is why IgG marks past exposure rather than current infection. A positive IgG result tells you the immune system has already met the virus. It does not tell you whether virus is present now; that is the question a PCR test answers.
Why does metabolic health matter in a viral infection?
A virus expresses itself according to the host’s biochemical capacity. That is why we argued in 2020 that metabolic health is a modifiable determinant of outcome, not a side issue during an acute crisis. Fewer than 12.2% of US adults were metabolically healthy in 2009–2016, and fewer than 7% are today. So the susceptible population is most of the country.
Related reading
Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP
Interventional pain physician, addiction medicine specialist and obesity medicine diplomate.
Licensed in Missouri and Illinois.
Last reviewed August 25, 2026
