def METHOD_NAME(series: pd.Series) -> pd.Series:
    series = pd.Series(series.values.copy(), index=series.index.get_level_values(CommonFields.DATE))
    index = series.loc[series != 0].last_valid_index()
    if index is None:
        # If test positivity is 0% the entire time, considering the data inaccurate, returning
        # none.
        series[:] = None
        return series
    series[index + pd.DateOffset(1) :] = None
    return series