evidence: India made several improvements in the immunization program including the AEFI surveillance system in the last decade but many daunting tasks remain ahead to sustain the gains made and achieve global benchmarks. As per the Global Vaccine Action Plan (GVAP), each country is expected to report at least 10 AEFIs for every 100,000 live births (estimated to be approximate 2600 for India) against the current number of approximately 1100 serious AEFIs annually [35]. With Mission Indradhanush (intensified immunization campaign) launched in 2015, India aimed to increase its full immunization coverage by 5 percentage points every year and succeeded in boosting immunization coverage by approx. 6.7% by vaccinating almost 2.1 crore children [36]. Additionally, UIP schedule expanded rapidly in last 3–4 y with the introduction of several new vaccines including Hib as Pentavalent, injectable Polio (IPV), MR, JE (endemic districts), Rotavirus and Pneumococcal Conjugate Vaccines [37]. The country thus needs to take steps for overall health system strengthening to achieve both i.e., expand the immunization coverage and increase documentation of the AEFIs, which is currently characterized by gross under-reporting. [...] Lahariya C, Paruthi R, Bhatacharya M. How a new health intervention affects the health systems? Learnings from pentavalent vaccine introduction in India. Indian J Pediatr. 2015;83:294–9. [...] Manoja Kumar Das & Narendra Kumar Arora