Parallelization of a prefix sum (Openmp)

I have two vectors, a[n] and b[n], where n is a large number.

a[0] = b[0];

for (i = 1; i < size; i++) {
        a[i] = a[i-1] + b[i];
}

With this code we try to achieve that a[i] contains the sum of all the numbers in b[] until b[i]. I need to parallelise this loop using openmp.

The main problem is that a[i] depends of a[i-1], so the only direct way that comes to my mind would be waiting for each a[i-1] number to be ready, which takes a lot of time and makes no sense. Is there any approach in openmp for solving this problem?