IAP also needs to deliberate on two other issues: (i) why do we need 2nd dose of varicella vaccine to prevent breakthrough disease with low vaccine coverage? In the USA need for second dose arose when vaccine coverage increased, resulting in low boosting effect provided by subclinical infections. Many cases of breakthrough disease have been seen recently. Could it be a case of poor response to varicella vaccine as has been observed that some Indian children had shown poor response to OPV? and (ii) what should be the interval between two doses of vaccine to prevent breakthrough disease in Indian children?