Scientists write: “It is unlikely that herd immunity can eliminate SARS-CoV-2,”

Exactly what that finding means is unclear, however. To and his colleagues make some sweeping statements in their paper, parts of which Science has seen. “It is unlikely that herd immunity can eliminate SARS-CoV-2,” the authors write, referring to the idea that the epidemic will peter out once enough people have been infected and become immune. “Second, vaccines may not be able to provide life-long protection against COVID-19.”

end partial quote from:

https://www.sciencemag.org/news/2020/08/some-people-can-get-pandemic-virus-twice-study-suggests-no-reason-panic 

The concern is that "Herd immunity" might not be possible with a virus like Covid-19 which might mean that this covid-19 might be more like a common cold in that there might not be a vaccine that could be developed because the virus keeps mutating like the common cold. So, it's possible you might need a vaccine every 2 months or so OR some other eventuality might be happening for the long term.

The virus needs to be studied more to see what the ongoing results are long term worldwide.

My son who has a bachelor's degree in Nursing told me this spring about how the problem is the similarity of this virus to the common cold and that you might not have a vaccine that can work ongoing because of this.

So, this particular virus might not have the possibility of herd immunity and so might keep killing and maiming around the world ongoing reducing world population on a yearly basis ongoing.

IF so, this will greatly change how world cultures have to deal with this.