def _robustness_check_params(params, date):
    """Remove drop in share_known_cases for Easter and simplify rapid test demand."""
    params = params.copy(deep=True)
    params = params.drop(
        index=[
            ("share_known_cases", "share_known_cases", "2021-04-01"),
            ("share_known_cases", "share_known_cases", "2021-04-05"),
            ("rapid_test_demand", "private_demand"),
            ("rapid_test_demand", "share_accepting_work_offer"),
            ("rapid_test_demand", "share_workers_receiving_offer"),
            ("rapid_test_demand", "educ_worker_shares"),
            ("rapid_test_demand", "student_shares"),
        ]
    )

    private_loc = ("rapid_test_demand", "private_demand")
    params.loc[(*private_loc, "2020-01-01"), "value"] = 0
    params.loc[(*private_loc, "2021-02-28"), "value"] = 0
    params.loc[(*private_loc, date), "value"] = 0.63
    params.loc[(*private_loc, "2025-12-31"), "value"] = 0.63

    accept_loc = ("rapid_test_demand", "share_accepting_work_offer")
    params.loc[(*accept_loc, "2020-01-01"), "value"] = 0.6
    params.loc[(*accept_loc, "2025-12-31"), "value"] = 0.6

    offer_loc = ("rapid_test_demand", "share_workers_receiving_offer")
    params.loc[(*offer_loc, "2020-01-01"), "value"] = 0.0
    params.loc[(*offer_loc, "2021-01-01"), "value"] = 0.0
    params.loc[(*offer_loc, "2021-03-01"), "value"] = 0.15
    params.loc[(*offer_loc, date), "value"] = 0.833
    params.loc[(*offer_loc, "2025-12-31"), "value"] = 0.833

    teacher_loc = ("rapid_test_demand", "educ_worker_shares")
    params.loc[(*teacher_loc, "2020-01-01"), "value"] = 0.0
    params.loc[(*teacher_loc, "2021-01-01"), "value"] = 0.0
    params.loc[(*teacher_loc, "2021-03-01"), "value"] = 0.3
    params.loc[(*teacher_loc, "2021-04-07"), "value"] = 0.95
    params.loc[(*teacher_loc, "2025-12-31"), "value"] = 0.95

    student_loc = ("rapid_test_demand", "student_shares")
    params.loc[(*student_loc, "2020-01-01"), "value"] = 0.0
    params.loc[(*student_loc, "2021-03-01"), "value"] = 0.0
    params.loc[(*student_loc, "2021-04-07"), "value"] = 0.95
    params.loc[(*student_loc, "2025-12-31"), "value"] = 0.95

    return params