ET, the danger is that some vaccinated people might suffer ADE (antibody dependent enhancement) if they get infected by the new strain, which is rapidly becoming the dominant strain. If I have interpreted that paper correctly (which isn’t particularly likely), the vaccine would prevent infection in people predisposed to mild covid, but through ADE would lead to worse covid in those predisposed to serious covid.
There are possible indications of sudden rises of hospitalisation in areas which had high prevalence in the first wave. This is the opposite of what we’d expect from acquired immunity, and may indicate ADE – those with mild or symptomless infection in the first wave requiring hospitalisation in this wave.
If this is so, those promoting herd immunity through real infection have got it entirely the wrong way around. So let’s keep an eye on the data while hoping this isn’t the case.