Authors
Dr Benny PV, Chief Editor, IMA Kerala Medical Journal; Professor, Department of Community Medicine, Sree Gokulam Medical College, Kerala, India.
Abstract
Background: The pentavalent vaccine, a five-in-one combination protecting against diphtheria, pertussis, tetanus, hepatitis B, and Haemophilus influenzae type b (Hib), was progressively introduced in Asian countries, replacing traditional DTwP and DTPwP-hepatitis B vaccines due to its ease of administration and reduced trauma for infants.
Observations: Following its introduction, several countries, including Sri Lanka, Bhutan, India, and Vietnam, reported serious adverse events following immunization (AEFI), some with fatal outcomes. These reports led to temporary vaccine suspension in some regions. For instance, Sri Lanka reported 4 deaths, Bhutan 5 encephalopathy cases, and Vietnam 27 fatal AEFI cases.
Review and Findings: Independent national and international expert reviews were conducted for all serious AEFI cases. These reviews consistently concluded that none of the fatal cases had a causal association with immunization, attributing mortalities primarily to pre-existing conditions such as congenital heart diseases. This led to the reintroduction of the vaccine in Sri Lanka and Vietnam, with children having known severe congenital heart disease vaccinated under close medical supervision.
Conclusion: The experience underscored the importance of thorough clinical investigation and autopsy for AEFI. WHO’s vaccine prequalification program plays a crucial role in ensuring the safety, quality, and affordability of vaccines. Currently, pentavalent vaccines from five different manufacturers are WHO-prequalified, offering significant public health benefits by protecting against five major health threats in a single injection.