Is the Delta variant more transmissible?
“Most studies indicate Delta is 50-60% more transmissible than the Alpha variant,” says Dr Bhramar Mukherjee, associate director for quantitative data sciences at the University of Michigan Rogel Cancer Center. “The Alpha variant itself was nearly 50-60% more transmissible than the original strain.”
This, according to Mukherjee, implies that if the reproduction number for the original strain was around 2.4-2.6, the one for Alpha is 3.6-4.2, and for Delta it is 5.6-6.7. In layman terms, if a person infected with the original strain could infect nearly two people, a person with the Alpha variant could infect four people. With Delta, one person could infect nearly seven other people. It’s important to remember that these are averages, not absolute numbers; one Delta carrier might infect zero people, or 25.
[...]
The other consequence of a higher reproduction number (denoted as R in epidemiological data) in an epidemic is that it increases the threshold for herd immunity. That is, more people will need to have the antibodies—either through infection or vaccination—to be protected as a community against the Delta variant. “With an R of 2.5, the threshold for herd immunity is 60%, but with an R of 6, it is 83%,” explains Mukherjee.
Delta variant, a strain of Covid-19 that likely wreaked havoc during India’s second wave has been identified in at least 85 countries. According to the World Health Organization (WHO), the delta covid variant is the most transmissible of all the variants identified so far. Acknowledging the...
qz.com