The most effective means of preventing malaria is sleeping under a mosquito net, specifically a long-lasting insecticide treated net (LLIN).
Malaria is transmitted by certain mosquitoes when they bite. These mosquitoes bite people to get a blood meal. The malaria parasite then passes from the infected mosquito to the person being bitten. They bite from dusk till dawn and that’s one of the most important things we have on our side: if we can protect people in affected areas when they sleep at night we have a very good chance of preventing them contracting malaria.

Every single net matters.