The sudden death of four children after they were administered measles vaccine in primary health centres in Tamil Nadu's Tiruvallur district is a grievous tragedy. That the deaths should occur in a State with a better record of health services delivery at the primary level is ironical. The involvement of the vaccine belonging to the same batch in different health centres seems to indicate problems with quality, which could have occurred at the point of manufacture, d uring transfer or storage. Laboratory investigations can determine whether the vaccine produced by the Human Biologicals Institute, Hyderabad, was contaminated, but the death of the infants is bound to shake public confidence in the immunisation programme. The priority must now be to restore faith in the system in order to maintain wide vaccination coverage. The benefits of good quality vaccines for diseases such as measles, mumps, diphtheria, polio, and tetanus are universally acknowledged and heavily outweigh the very rare adverse reactions. The Tamil Nadu government has offered succour and cash relief to the families of the children, but some aspects of the Tiruvallur calamity point to gaps in district-level healthcare delivery. Despite improvements made to the PHC network, equally serious attention has not been devoted to upgrading emergency services in the district government hospitals. In an hour of crisis, several patients are compelled to travel to apex institutions in Chennai and other major cities from neighbouring districts, as it happened in the vaccination case, often in panic and at great personal expense. The heart-rending vaccination deaths must occasion a review of immunisation programmes by all States. The Central Drugs Standard Control Organisation, on its part, needs to strengthen regulatory oversight on vaccines. As the World Health Organisation points out, in most cases, it is not the vaccines that cause adverse events; the majority are attributable to preventable errors in storage, handling or administration. To that list, we must add the lack of emergency response systems. It has been possible for some time now to ensure the integrity of the cold chain, so vital for vaccine efficacy, with the help of vial monitors