How does Leon not get infected?

How does Leon not get infected? They are only bitten for gameplay purposes. Lorewise they never get bitten. If I recall correctly, it’s stated in one of the Resident Evil games that the herbs (green, blue and red) have properties that counteract the virus.

They are only bitten for gameplay purposes. Lorewise they never get bitten. If I recall correctly, it’s stated in one of the Resident Evil games that the herbs (green, blue and red) have properties that counteract the virus.