Hi Amanullah,
The rationale you hear most is that a child with SAM has some level of depression of the immune system and will respond better to the vaccine if it is given after the child has had some recovery time in OTP. The first time I saw it appear in guidelines was in 2007 (though it may well have also been done before that). Since then it appears to have become a standard protocol.

In the old CTC emergency programmes we used to vaccinate on admission (and if the child was less than 9 months old on admission - again at discharge).

I am ambivalent about the '4th week' protocol, I think we should consider context. If this is an emergency programme, in an area where there is low measles vaccination coverage or there is a problem with high, early default rates (i.e. children default before week 4) then it is worth considering vaccinating on admission.

According to Dr Jean-Marie Okwo-Bele, Director of Immunization, Vaccines and Biologicals at WHO. ""Most of the children that remain un-immunized are the same ones missed by health systems, children most likely have also not received any of the other basic health services. If we are to raise the bar on global immunization coverage, health services must reach the unreached. Every contact with the health system must be seen as an opportunity to immunise."

In a stable context with good vaccination coverage and a well functioning health system that has regular child health days for example, vaccinating the child on admission would be less of a priority and we could wait until the 4th week.

I am sure there will be lots of varying opinion, however ultimately we should follow the National Guidelines unless an exception has been negotiated with the relevant Ministry of Health since these issues are normally discussed when drafting guidelines.

I hope this helps.

Thanks