Figure 4
From: Sars-Cov2 world pandemic recurrent waves controlled by variants evolution and vaccination campaign
Wavelet and Fourier Transform of epidemic spreading in United States, United Kingdom and Japan from 15/03/2020 to 28/01/2022. The Covid-19 spreading is visualized vs. time by wavelet transform giving the Local Wavelet Power Spectrum (LWPS) of the RIC index and the daily deaths per million population (Df) time series in the upper panels. The wavelet analysis decomposes the spreading waves hidden in time series data at different scales. Power is color-coded from − 1 (blue) to 1 (red). In the lower panels we show the Global wavelet power spectrum (GWPS) of the period of epidemic periodic travelling waves for infections measured by the RIC index and the new deaths, before the vaccination campaign for t < tv (black lines) and after the onset of the vaccination campaign for t > tv (red lines).
