06-17-2021, 06:53 PM
Ca Bob wrote:
Well, the RNA dependent RNA polymerase that replicates the Covid-19 genome gets it right 9999 times out of 10,000 which means that in an average replication, there are 3 mutations on the average (most probably neutral) and in an average human case there will be something like billions or trillions of new copies of the virus. This presumably means that every single nucleotide in the viral genome gets changed at least once as it goes through any human with severe illness. Some runs of nucleotides get changed. There is also evidence for a kind of strand switching in which one viral genome ends up mixed with another. So there is a lot of mixing and switching and mutating going on. Probably the only thing protecting us from an immediate super virus is that there is only so much that this one little genome can do and, in addition, the virus particles that escape a sick individual to infect someone else are going to be the ones that replicate effectively and find their way into exhaled vapors and cough particles. Mutations that damage these processes will be lethal to the virus. On the other hand, a mutation which works a little more efficiently in a particular population will get the edge when there are thousands of new cases.
To add to this-- mutations in the RNAD-RNA Pol itself can reduce replication fidelity, so that we end up with even more mutations, plus the fact that the virus has known mutational hotspots. And the strand swapping to which you're referring can happen with a person who is co-infected with more than one coronavirus, which one could see happening especially in cold-weather months (see below). So yeah, we're dealing with a "when", not an "if", kind of situation here.
sekker wrote:
We are playing the horrible game of 'Pandemic Russian Roulette' until we truly stop the virus from growing.
The only good news I've heard is that the non-B cell immunity seems to effective against all of the known common variants.
We will see whether COVID-19 is more like polio, where a single vaccine will work for years (even though all viruses can mutate), or whether it will be like the seasonal flu.
My guess is that it will be the latter. Coronaviruses make up an estimated 10-20% of all "common cold" cases, and someone -- sooner or later -- might get co-infected with both viruses. Then all hell breaks loose. (The difference, as I see it, is that polio is not running around rampant right now...)
Non-B cell immunity is good, but not for everyone... there are the immunodeficient/immunocompromised to think of. Also, even non-B cell immunity wanes over time... the estimate for MERS and SARS was that immunity might last 2-3 years at most.
And yes, we need to keep this damned virus from replicating. The 60% or so in my state who refuse to get vaccinated aren't helping matters...