No affects have been found.
> In 1872, the Victorian scientist Francis Galton made the first statistical analysis of third-party prayer. He hypothesized, partly as satire, that if prayer were effective, members of the British Royal Family would live longer than average, given that thousands prayed for their well-being every Sunday, and he prayed over randomized plots of land to see whether the plants would grow any faster, and found no correlation in either case.
https://en.wikipedia.org/wiki/Studies_on_intercessory_prayer