Odds ratios standard errors, CIs, etc are calculated on the log of the odds.
Here's some R code. First we'll take the log of the odds:
OR <- 0.997804
ORL95 <- 0.970573
logor <- log(OR)
logorl95 <- log(ORL95)
Then calculate the difference between the odds ration and the lower (or upper, it doesn't matter, they're the same) confidence limit.
diff <- logor - logorl95
The confidence limit is 1.96 * se, so:
seor <- diff / 1.96
z is estimate / se.
z <- logor / seor
Let's calculate p, just to make sure we didn't make a foolish mistake along the way:
(1 - pnorm(abs(z))) * 2
Here are the important bits of the output:
> (1 - pnorm(abs(z))) * 2