I’ve Got a Bad Feeling About This
So, we have a pandemic, somewhere around 10% of the people who get sick get long Covid, there is evidence of long lasting damage to the immune system, and now there are indications that the BA.4 and BA.5 variants may be more contagious than measles.
For those of you who do not have a passing acquaintance with infectious diseases, measles is generally considered the most contagious common disease in the world. (Lepros: is the least contagious, but I digress)
When I called this disease, “The Andromeda Strain,” I did not know the half of it:
COVID was relatively deadly, but not ultra-transmissible when it burst onto the global scene in late 2019 and early 2020.
Globally dominant Omicron subvariants BA.4 and BA.5 are neck and neck with measles in the competition for the title of most infectious disease known to man, according to an Australian professor of biostatistics and epidemiology.
The original Wuhan strain of COVID-19 had a reproductive rate — also known as an R0 or R-naught value — of around 3.3, meaning that each infected person infected another 3.3 people, on average. That put COVID-19 among the least transmissible human diseases.
Slightly less transmissible were the 1918 pandemic strain of flu, which had an estimated R0 of 2, along with Ebola. On the higher end of the spectrum, mumps has an R0 of 12; measles tops the list at 18.
New studies suggest that BA.4 and BA.5 have a growth advantage over BA.2 similar to the growth advantage BA.2 had over BA.1. Thus, the latest dominant COVID subvariants have a reproductive rate of around 18.6, tying or surpassing measles, the world’s most infectious viral disease, according to Esterman.
The next dominant COVID strain should surpass them all. BA.2.75, an ultra-new Omicron subvariant nicknamed “Centaurus” by some on Twitter, made headlines this week after the World Health Organization said it was tracking it. It’s already on the heels of dominant BA.5 in India, with “apparent rapid growth and wide geographical spread,” according to Tom Peacock, a virologist at the Department of Infectious Diseases at Imperial College in London.
Its reproductive rate is yet unknown.
The pandemic is not even near over.