This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
Supplementary immunisation services for measles immunisation? 
Select and explain. 
A. Keep up with > 95% immunised, B. Catch up, C. Follow up, D. All the above
D: All the above
Answer: D: All the above 
Explanation: WHO Measles Elimination strategy : Catch up, Keep up, Follow up. Catch up: Nationwide, vaccination targeting all children 9 months to 14 years of age, irrespective of history of Measles disease or vaccination status Keep up: Routine services aimed at vaccinating more than 95% of each successive bih coho. Follow up: Subsequent nationwide vaccination campaigns conducted every 2-4 years targeting usually all children born after the catch-up campaign Ref: Park 25th edition Pgno : 161-162