Sinovac protocol calls for a 14 day interval before second shot, but three weeks has proven to be more effective. There is no 30 day detail. https://torontosun.com/news/world/s...ne-more-effective-with-longer-dosing-intervalThe person who filled out your card seems to have misunderstood the detail of one month after the first injection. Other countries have been doing Sinovac at two week intervals, so it is probably close enough for horseshoes, hand grenades and two dose vaccine delay periods.