[Python] What is the most efficient way in Pandas to search for dates entries in a dataframe...

I am trying to determine whether a given set of obstetrics patients have recieved their flu shots in the current flu season.

That is, I have essentially three dataframes:

>>> edds
name expected_delivery_date
0 Susan 2024-12-01
1 Susan 2023-10-01
2 Marie 2024-10-15

>>> flu_shots
name flu_shot_date
0 Susan 2023-09-01
1 Marie 2022-09-01


>>> flu_season_begin_dates
0 2024-09-01
1 2023-09-01
2 2022-09-01
3 2021-09-01


What is the most efficient way to identify which women got a flu shot (a) before their due date but (b) on or after the start of the most recent flu season?

>>> got_flu_shot
name expected_delivery_date got_required_flu_shot
0 Susan 2024-12-01 False
1 Susan 2023-10-01 True
2 Marie 2023-10-01 True



I can think of going row-by-row by (name, expected_delivery_date) and searching for the "most recent flu shot before the delivery" and "most recent flu season start date" but that feels inherently inefficient.

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