Secondary Look at Secondary Attack Rate, Over Two Years into a Pandemic

Better Late Than Never?

Prior to an evolving science, in which even doctors and public health professionals exhibited fear of demonstrating ethics and moral courage, reproductive number, or R-Naught, had been expressly rejected by the CDC, because it is not a rate, and is only a projection based upon mathematical and stochastic models.

But in evolving science, respiratory protection became synonymous to source control, asymptomatic signs of infection became synonymous with symptoms, efficacious became synonymous with effective and herd effect became synonymous with herd immunity, and if you are lost in this conversation, welcome to the two year medical inside joke.

A household transmission secondary attack rate study was performed and published by JAMA in December, examining cases in 95% vaccinated Norway, from December 1, 2021 to January 8, 2022, establishing a global secondary attack rate of only 19.7%, still 0.3% too low to validate the presence of an infectious virus. They probably chose Norway because of the high vaccines compliance, but the disaggregated data found a 25.1% secondary attack rate for the omicron variant, validating it as an infectious, and only infectious, not highly contagious, disease, typical profile of an exit strategy biological agent. Delta was found to possess a 19.4% secondary attack rate and the unclassified varieties at 17.9%. With the original variant, the Deputy Director for the Bloomberg School of Public Health was trolling me on Facebook, claiming that a case review of household transmission studies, all in Asia and the Sino Pacific, had found secondary attack rates ranging from 4.6 to 49.56, in pretty large sample sizes, which one biological agent will only present based upon a difference in vulnerability factors for the population, which should have been sorted out in large sampling, or indicative of some exposure factor, probably unnatural. And very odd to appear in so many household transmission studies and not just one outlier. But most significant was that, like the 25.1% secondary attack rate for omicron, no study found a secondary attack rate at the 60% threshold to validate a highly contagious disease that can set off a super spreader event.