“Herd immunity” to coronavirus might be precluded by the fact that coronaviruses induce poor natural immunity. The virus interferes with the innate immune response, and this interferes with adaptive immunity.
The problem with a vaccine is that in some cases the presence of antibodies can exacerbate the disease.
This report explains the reinfection risk. Apparently, reinfection is more prevalent among the young than the old.
Until more is learned, the focus should be on cures. The Hydroxychloroquine/Azithromycin Treatment of Covid-19 seems to work well if given early enough. It seems less successful if given as a last resort.
Dietary improvements to boost immune response seems to be a cost effective way to hamper the virus’ attack on the body.
According to this report—https://www.lewrockwell.com/2020/04/no_author/anti-parasitic-agent-ivermectin-abolishes-coronavirus-particles/  —Ivermectin, a widely used anti-parasitic agent, is an effective killer of the coronavirus.
Until much more is learned about the virus, success against it requires getting outside of the profit-driven Big Pharma imposed box of medical orthodoxy. If zinc, vitamin C, Ivermectin, Hydroxychloroquine and Azithromycin are effective treatments, they should be used.