Will over-the-counter insect repellant prevent mosquito bites and malaria infection?

Any that... ...Contain deet, at this time deet is the most effective repellent.
Mosquitos. Yes to mosquitos but no to the prevention of malaria which is transmitted by mosquitoes is different locations around the world.

Related Questions

Will over-the-counter insect repellant prevent sandfly bites and leishmaniasis infection?

Possibly... This answer can best be found on the labels of the 'insect repellants'; read them to find out. I do not believe there is a repellant for leshmaniasis though. Read more...
No. Unless it specifically states that it protects against these insects, there is no protection provided. Read more...