MMR and Autism: There have been allegations by a small number of researchers that MMR is associated with autistic disorders in vaccinees, but recently many studies showed that there is no temporal relationship between MMR immunization and development of autism.

MMR and Inflammatory bowel diseases (IBD): Few studies proposed the epidemiological association of IBD and MMR vaccine or measles vaccine alone in view of following reasons:- Measles virus antigen was found in intestinal wall of some patients with IBD, few patients had higher concentration of serum measles IgM and in a few wild type measles virus was found in peripheral blood monocytes. To date available literature does not support an association between measles containing vaccines and risk of IBD.

MMR and Central Nervous system disorders: Few cases of aseptic meningitis, meninges encephalitis and Guillain Barre Syndrome have been reported after MMR vaccination. But recent work from UK and South America do not support a causal association.

Hyper sensitivity reactions: MMR vaccine contains hydrolyzed gelatin as a stabilizer. So persons having history of an anaphylactic reaction to gelatin or gelatin containing products should be vaccinated with MMR with extreme caution.

Mumps antigen and the chances of aseptic meningitis: 3 cases of Aseptic meningitis were reported following use of Urabe MMR from Canada in 1987. The Urabe MMR was recalled from Canada in 1988. Urabe MMR was introduced in UK in 1987-88 and 1 case was reported in the pre-licensure study. The risk estimated varied from 1 in 10,000 to 1 in 100,000. Meanwhile similar cases were reported from Japan too. In 1991 active surveillance program started in UK. The risk of aseptic meningitis was estimated to be 1 in 143,000. This led to withdrawal of Urabe MMR in September 1992 and it was replaced by the JL strain MMR. The active surveillance continued and the risk was estimated to be 1 in 143,00 with Urabe and 1 in 227,000 with JL strain (p: 0.0096). This proves that the Jerryl Lynn strain is much safer. However the JL strain containing MMR vaccine is 3-4 times more costly than Urabe strain MMR. In west the Urabe strain is not used at all and most of the countries use JL strain. The JL strain containing MMR is available now in the Indian market. It may be worthwhile offering the same to those who can afford the extra cost, as it is definitely safer than the Urabe strain MMR. Incidentally aseptic meningitis is rarely reported following Urabe strain MMR from developing countries. This may be another reason for continued use of this vaccine in India.