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There's another reason why an effective vaccine is going to be unlikely in the short term. First HIV has been around for 40 years and there is still no vaccine, some of the sequences on the spike protein for this virus have HIV homology. Secondly is, the SARS virus vaccine trials on animals revealed a mechanism known as Antibody-dependent enhancement https://en.wikipedia.org/wiki/Antibody-dependent_enhancement which means if you get vaccinated with these vaccines then you are actually making yourself more susceptible to the virus because it hijacks the antibodies you created for it to attack your cells more readily. Which is the same mechanism that can also be triggered by a second strain of the virus which is similar but different enough to trigger a second immune response, in some cases progresses to a massive immune over-reaction, i.e. cytokine storm. (It's evil don't hyperventilate yet but just don't get it the first time). Some commentators speculated that those video clips from Wuhan and S. Korea of people collapsing in the street were cytokine storm victims who had somehow got an ADE response from a second virus infection. All that 80% mild case talk is dangerous because those people might have just made themselves vulnerable to secondary lethal infection regardless of how young healthy fit they are. In fact in that case a vigorous immune system is the threat because that is what will get you the second time around, your own body's immune reaction.

We are early days in understanding this beast.