| Value | Category | 
                                    
                    
                        | 0 | No | 
                                    
                    
                        | 1 | Vaccination date on card | 
                                    
                    
                        | 2 | Reported by mother | 
                                    
                    
                        | 3 | Vaccination marked on card | 
                                    
                    
                        | 8 | Don't know | 
                                    
                    
                        | 11 | .C | 
                                    
                    
                        | 2147483624 | Missing | 
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.