Analysis shows viral shift as reason for end of COVID-19 pandemic

New analyses suggest that the dramatic decline in COVID-19 deaths between 2022 and 2023 may be due to an abrupt phase transition in the molecular structure of the virus's spike protein.

In the winter of 2020/2021, there were 250,000 deaths from COVID-19 in the United States. The following year, that number rose by a third to 330,000. But from August 2022 to March 2023, the number of COVID-19-related deaths dropped to just 80,000, bringing the COVID pandemic to an abrupt end. This dramatic decline could not be attributed solely to vaccines, which had already been widely available since spring 2021.

New research published in EPJB Marcelo Moret of CIMATEC in Brazil and James Phillips of Rutgers University in New Jersey suspect that a phase transition in the molecular structure of the COVID-19 spike protein made the virus less likely to cause severe infections. Their findings provide important insights into how the pandemic ended so quickly and could help us prepare for future pandemics.

The spike protein protrudes from the surface of viruses like COVID-19 and facilitates entry into host cells by binding to specific receptors on cell membranes. When the virus mutates, these proteins can change rapidly: This improves the virus's ability to bind to receptors, but in some cases also makes it less deadly.

In their study, Moret and Phillips investigated the relationship between mutations and death rates. They discovered that a phase transition in the molecular structure of the spike protein – comparable to transitions between phases of matter in physics – could be directly responsible for the sudden drop in deaths. This phase transition occurred in new strains of the omicron variant that emerged in 2023 and had only 5 additional mutations compared to the original omicron variant.

The duo's study suggests that this transition altered the virus's binding mechanisms in the upper respiratory tract – the passages that connect the nose, mouth and throat – making severe infections less likely. This finding not only improves our understanding of COVID-19's evolving contagiousness, but also offers valuable lessons for preparing for future pandemics. Through future research, Moret and Phillips hope to further solidify these theories and gain deeper insights into how future pandemics may evolve.