  The 6th wave of COVID-19 in Tokyo continued for the longest period of
infection (about 190 days from late Nov. 2021), and the 7th wave, which
occurred in mid-May 2022, was the largest wave ever (cumulative 1.7 million
people). In order to elucidate their factors, the infection wave was analyzed
by using the Avrami equation. The main component of the 6th wave was formed by
the coupling of increased human interaction due to the New Year holidays and
the invasion of the new virus variant Omicron BA.1. After that, side waves were
formed by the coupling of the invasion of the new virus variant Omicron BA.2
and the human interaction in the consecutive holidays in February, March, and
May. These side waves caused the 6th wave not to converge for a long time. The
outbreak of the main component of the 7th wave occurred by the coupling of the
invasion of the new virus variant Omicron BA.5 and multiple social factors,
followed by human interaction during the July holidays. Based on the results
that the domain growth rate $K$ and the infection rise time $t_\mathrm{on}$
were almost independent of the initial susceptible $D_\mathrm{s}$, dense
nucleation followed by a near growth model was deduced. The quantity $K \cdot
t_\mathrm{on}$ was considered to represent the infectivity of the virus.
