  We compute the allele frequencies of the alpha (B.1.1.7), beta (B.1.351) and
delta (B.167.2) variants of SARS-CoV-2 from almost two million genome sequences
on the GISAID repository. We find that the frequencies of a majority of the
defining mutations in alpha rose towards the end of 2020 but drifted apart
during spring 2021, a similar pattern being followed by delta during summer of
2021. For beta we find a more complex scenario with frequencies of some
mutations rising and some remaining close to zero. Our results point to that
what is generally reported as single variants is in fact a collection of
variants with different genetic characteristics. For all three variants we
further find some alleles with a clearly deviating time series.
