COVID-19 is transmitted by tiny droplets or airborne particles that contain the virus. They can be inhaled over longer distances, especially indoors, but the risk is greatest when people are close together.
Newly Developed Model Describes Covid Waves & Plateaus Accurately
If contaminated liquids are splashed or sprayed in the eyes, nose, or mouth, or if contaminated surfaces are touched, transmission can occur. Even without showing any symptoms, people are contagious for up to 20 days.
Through a collaboration between the Department of Energy’s Brookhaven National Laboratory, the University of California San Diego, and the University of Illinois Urbana-Champaign, researchers developed an analytical method that helps researchers better understand the wave dynamics of COVID-19.
Using real-world studies of proximity data, the researchers developed a model that incorporates social activity that tends to increase rapidly for short periods and then revert to more moderate levels after longer in-between times.
As people breathe, talk, cough, sneeze, or sing, droplets and small airborne particles that infected people exhale are mainly transmitted by the respiratory route.
A person with COVID-19 who is physically close to another who has the virus is more likely to spread it. Nonetheless, longer distances can cause the virus to transmit, particularly inside buildings.
To introduce COVID-19 vaccines, an updated stochastic social activity model and a traditional epidemiology model were combined, as well as empirical data from four states in the United States.
Individual social activity is described as stochastic when it is unpredictable and random, a variable that can nevertheless be numerically represented by probability distributions that accumulate with time.
The new model builds upon a paper published in April of the Proceedings of the National Academy of Sciences demonstrating that “herd immunity” does not apply to the COVID-19 pandemic because it proves to be short-lived.
They coined the term “transient collective immunity” to describe the fragile and temporary state that emerges. Prior research also showed that individual social networks differed in size.
Whether or not individuals change their social behavior in response to information about current infection rates is included in the model; the team reports in the current work that this newly accounted-for random factor will always result in waves or plateaus of infections.
A similar trend could be seen with COVID-19 becoming endemic in the global population over time, in the manner of a cold or flu.
In our new model, we explain three observations: how waves cease when there is a pandemic, why they grow at a close to a constant rate, and why new pathogens often become endemic during this process.”.
According to classical theory, introducing a new pathogen eventually kills itself off when enough people get infected that herd immunity develops unless it has a very short-term immunity.
Alexei Tkachenko, the physicist at the Center for Functional Nanomaterials at Brookhaven Lab and lead author of the paper, says that even with long-term immunity, a new pathogen may remain endemic for generations”.
“Here, we add the factor that contributes to the dynamics of multiple waves of a pandemic. In our case, there is a change in social activity levels that permanently drives our model’s waves. According to Sergei Maslov, professor of bioengineering and physics at the University of Illinois Urbana-Champaign and Bliss Faculty Scholar, “the fluctuations in activity level affected the spread of infection in waves and plateaus.”
Based on official reports from national public health agencies, 8.53 billion doses of the COVID19 vaccine have been administered worldwide as of December 15, 2021.
Countries have ordered around 11 billion vaccine doses, and more than half of the doses have been purchased by countries with high incomes, which comprise 13% of the world’s population.