  Here it is proposed a decomposition in components of the''waves'' which
appear in the time series of data related to Covid-19 pandemic. The
decomposition is based on functions of \k{appa}-statistics; in particular the
\k{appa}-Weibull is used. Fitted data are those of the ''waves'' ranging from
August 2020 to April 2021 in the United Kingdom, from September 2020 to May
2021 in Ireland, and from September 2020 to June 2021 in Italy. For the United
Kingdom, the time series of daily infection shows a wave composed by two peaks.
Among the many factors involved in the spread of infection, it seems that, in
driving the onset of the second peak, the main role was played by the emergence
of Alpha variant of Sars-Cov-2. Therefore, the proposed decomposition of waves
in the time series is applied to study the role of Alpha variant in the spread
of infection. For what concerns data from Ireland, if we decompose the analysed
''wave'' in three components, we can observed that for one of them the role of
the Alpha variant was relevant for sure. In the case of Italy, the effect is
less evident, because it was spread over a larger time interval.
