Errors in dates

[choisy]

For information, it appears that it will be very difficult to correct for these errors in dates as Thai says that neither NIHE nor Viettel will correct them and that it will have to be corrected by the health centers / immunization facilities, which I doubt they will in absence of incentives. It's certainly a problem for us, but that's life and we'll have to accept this imperfection of the data. Thus, I would recommend to

1. just get rid off these data
2. quantify them by vaccine type, province and time in order to have an idea of the damage

Note that all these children that were born before 2017 should be discarded anyway.

[duhongduc]

Solved