The Unsolved Mystery of How Viruses Spread – and Why Germ Theory Isn’t the Whole Answer

 For over a century scientists have struggled to prove viral contagion. There are gaping holes in the current model of viral transmission but these holes are not a reason to throw out the concept of a virus. We need a new model that fits the evidence. Here I set out the evidence for and against the current model and suggest a way to reconcile the apparent contradictions. 

Evidence for viral contagion 

1. Viral genetic material turns up in clusters of sick people. The sequences match. They change over time with new mutations in consistent ways without reverting. Even though testing is not perfect, people with positive tests are far more likely to be sick than not.
2. Viruses have been well described. Even if isolation methods are not flawless, electron microscopy and crystallography have shown fine-grained details including the shape of structures like the surface of the spike protein.
3. At high doses, transmission works. Human challenge trials demonstrate that viral exposure can cause illness when the dose is high enough.
4. Genetic tracing of viruses during outbreaks shows that distinct lineages spread from person to person in predictable clusters, confirming person-to-person transmission.

This evidence explains the mechanism of viral infection. But it does not explain the timing of the waves of infection that are characteristic of many viruses like influenza.

Where the traditional model fails

1. Normal-dose challenge trials often fail. The evidence here is strong: under experimental conditions, exposure frequently does not result in illness. A recent study confirmed this again.
2. Hospital-acquired infections peak at the same time as cases in the community. If spread were primarily driven by close contact, we would expect a lag, as community infections peak then admissions then within hospital infections. But the expected lag does not occur. In fact, hospital-acquired infections peak before the admissions to the hospital.  
3. Waves occur with seasonal regularity. Epidemic peaks in the UK often occur with peak deaths at predictable times of year before falling away for a time:
   • Every early January
   • Often early April
   • Sometimes in July
   • Every late October....<<<Read More>>>...