A great cause would be supply chain in countries/regions with poor infrastructure and/or uncertain supply and high price fluctuations.
This is particularly important in many developing countries, because getting supplies to their destination and being able to do so on time is not straightforward.
Another amazing cause is to formulate & solve travelling salesman problems in order to figure out how medical personnel can effectively vaccinate a population, both before & during an outbreak.
These problems have absolutely unique constraints and dynamics, e.g., figuring out how to create herd immunity whilst avoiding a certain peninsula because warlords have been at war with each other & raiding villages for the last 3 months.
As you can imagine, niche technical expertise is not easy to find in NGOs & charities, and neither is specialised software for their unique needs, so these kinds of technical contributions can have massive impact in improving people's lives.
There are numerous ways to participate, e.g. through student initiatives, clubs, and internships for our younger people, or pro-bono work for the professionals. A notable factor here is the Bill & Melinda Gates Foundation, which has been instrumental in funding technological solutions in developing & developed countries alike - it's worth checking out their full range of activities for more details.