It is now greater than 2 throughout most of the country and exceeds 2.5 in the densely populated province of Gauteng, as well as KwaZulu-Natal and Mpumalanga provinces. But then R t shot up suddenly in mid-November. On December 9, South AfricaвЂ™s National Institute for Communicable Diseases (NICD) reported that by early November, R t in that country had stabilized at values below one, signifying cases were actually falling during a period when Delta was the dominant variant and it ran up against widespread immunity in the population. R t estimates for Omicron are now emerging. вЂњWe use it to determine how fast an outbreak is growing, or shrinking.вЂќВ A value of R 2, for instance, means that one person will infect two others while a value of R 5 means the person will spread the virus to five individuals, increasing the number of infected people much faster.

R t вЂњcan change from minute to minute depending on real-world conditions,вЂќВ Lipsitch says. The variable вЂњtвЂќ represents the number of secondary infections and depends on the effects of other peopleвЂ™s immunity, seasonal weather patterns, public health interventions, and other limits on viral transmission. In an ongoing pandemic, scientists try to capture that estimate with a value called the effective reproduction number, or R t. вЂњDoes it bind more easily to receptors in peopleвЂ™s lungs? Do you shed it more efficiently and spew more of it out so you can infect more people?вЂќ Immune system evasion, on the other hand, is the capacity of the virus to avoid antibodies that would otherwise mark it for destruction by the body, as well as an ability to dodge various immune system cells.ДЄ key step in gauging a virusвЂ™s spread is to start with one infected person and estimate how many other people will get the virus from that individual. вЂњIt depends on all sorts of biological processes,вЂќ explains Jeffrey Shaman, an infectious disease modeler at Columbia UniversityвЂ™s Mailman School of Public Health. Transmissibility reflects the virusвЂ™s ability to replicate in human cells and move from person to person. Untangling how much transmissibility and immune evasion each contribute to the variantвЂ™s spread is вЂњwhat will allow us to predict how many people Omicron might infect and how fast,вЂќ says Marc Lipsitch, an epidemiologist at the Harvard T.H. The second is its capacity to evade human immune systems. One is its innate contagiousness, or transmissibility. Scientists are now trying to model OmicronвЂ™s global trajectory, which depends on two factors. In South Africa, where OmicronвЂ™s 50 or so mutations were first identified, the variant has shown that it can reinfect people who already caught and survived earlier versions of the SARS-CoV-2 virus, as well as people who have been vaccinated against it.

New travel restrictions and mounting anxiety have followed this heavily mutated version of the coronavirus, which has been reported now in more than 60 countries. The Omicron variant is spreading rapidly worldwide.

Rapid sketch tablet version