This paper further supports the fact that naturally acquired immunity to SARS-CoV-2 is 1) robust and 2) durable. 1) Robust means the immune response recognizes many different parts of the virus. 2) Durable means the immune response remains detectable - and likely effective at protecting the individual - for a long period of time. A robust immune response is important because it provides a certain degree of protection…
Reference [2] is...it says just as much about the efficacy of vaccination as the efficacy of natural immunity:
> The cumulative incidence of SARS-CoV-2 infection remained almost zero among previously infected unvaccinated subjects, previously infected subjects who were vaccinated, and previously uninfected subjects who were vaccinated, compared with a steady increase in cumulative incidence among previously uninfected subjects who remained unvaccinated.
Read reference [3] to understand why natural immunity doesn't cut it. Note that widespread natural immunity causes the same positive selection pressure as widespread vaccine deployment, and:
> Finally, our work suggests that immune evasion requiring one to two mutations occurs within months, raising the prospect that this phenomenon will further shorten the duration of natural immunity...
The paper goes on to provide (under Discussion) a series of strategies for developing a vaccination system that takes into account modelled viral evolution. Can't come up with strategies like that for natural immunity, apart from: "periodically re-infect individual"...which is exactly what vaccines do, in a controlled manner.
Reference [4] and [5] are research tabulating mutations the virus is undergoing to counter both natural acquired and vaccine-mediated immune responses. It is not an indictment against vaccines, but just like paper [3], provide strategies on how to update vaccines. That updates will be required is not a surprise to anyone. Viral evolution has long been known of, and no one expected the emergency COVID-19 vaccines to be effective until the end of time.
Reference [6]...did you read it? It's about vaccines which protect the host(keep them alive), but still keep them infectious (capable of transmission). None of the COVID-19 vaccines do that...