Prescriber Update 23(1): 4-5
Medsafe Editorial Team
Recent studies have confirmed that there is no association between infant immunisation and sudden infant death syndrome, between MMR vaccine and either autism or bowel disease, and between hepatitis B vaccine and multiple sclerosis.
The Medicines Adverse Reactions Committee (MARC) has reviewed recent studies of some suspected vaccine adverse reactions. This article reflects the views of the Committee and updates advice in earlier Prescriber Update articles.1-4
Studies,5 including one6 conducted in New Zealand, have found no association between sudden infant death syndrome (SIDS) and childhood vaccination. SIDS occurs in infants at the age at which they are receiving their immunisations. Hence, close temporal relationships with vaccination are inevitable in some cases.
A recent case control study conducted in the United Kingdom7 included a base cohort of 470,000 births and identified 303 deaths attributed to SIDS. The odds ratio for SIDS with vaccination uptake (DTPH and oral polio vaccines) after adjusting for matching and the infants' sleeping environment was 0.67 (95% confidence interval 0.31-1.43). Five percent of SIDS deaths and reference sleeps (the reference sleep for each control infant occurred in the period of the day in which the matched case infant had died) occurred within 48 hours following vaccination. Babies who died of SIDS were more likely to have needed medical attention in the 24 hours before death than their matched controls (21% and 7%, respectively). The results of this study7 are consistent with there being no association between DTPH and oral polio vaccination and SIDS.
The assertion that there was an association between MMR vaccine and autism, as a result of bowel abnormalities, was made by Wakefield et al8 in 1998 on the basis of a case series. However, subsequent evidence has not supported this alleged association.3,9 Two recent studies have compared the rate of uptake of vaccination with the rate of diagnosis of autism over time using United Kingdom10 and Californian11 data. Both studies found steep rises (5- to 7-fold) in the number of cases of autism occurring over periods for which the uptake of MMR vaccine was almost static (about 97%) in one study10 or increased by a small percentage (10%) in the other.11 The increase in uptake of MMR vaccine could not account for the rise in diagnosis of autism in either study. A further study12 found no association between MMR vaccine and a distinct syndrome of autism involving regression or autism coupled with gastrointestinal symptoms. A recent review13 has summarised the evidence regarding MMR vaccine and autism.
Initial findings of an association between exposure to measles in utero or measles infection in early childhood and inflammatory bowel disease later in life have not been confirmed.3,14 A recent case control study15 of 142 persons with inflammatory bowel disease found no association with MMR or other measles-containing vaccine. However, the authors considered that a small increase in risk would not have been detected in their study. The MARC considers that the overall balance of evidence is not consistent with an association between MMR vaccine and bowel disease.
Recently the American Academy of Pediatrics16 published its conclusions that the available evidence does not support an association between MMR vaccine, autism and bowel disease. The American Institute of Medicine17 reached a similar conclusion with regard to autism.
Three recent studies have examined the possibility of an association between hepatitis B vaccine and demyelinating disease, specifically multiple sclerosis. One study18 conducted in adolescents in British Columbia found no difference in incidence of multiple sclerosis before and after initiation of the hepatitis B vaccination programme.
Another study19 using the cohort of women in the US Nurses' Health Study identified 192 women with multiple sclerosis and matched these to 534 healthy controls. After adjustment for age, the relative risk of multiple sclerosis in women vaccinated with hepatitis B vaccine compared with unvaccinated women was 0.9 (95% CI 0.5-1.6). Restricting the analysis to those vaccinated within two years of the onset of disease did not increase the association.
The third study20 looked for an association between relapse and vaccination with any vaccine in 643 patients diagnosed with multiple sclerosis who had been relapse-free in the 12 months preceding the relapse. In this study exposure to vaccination in the 2-month period immediately preceding the relapse was compared with exposure in the preceding relapse-free 2-month periods. The relative risk for relapse with hepatitis B vaccine was 0.67 (95% CI 0.20-2.17).
None of these studies found evidence for an association between hepatitis B vaccine and multiple sclerosis or relapse of multiple sclerosis.
Competing interests (authors): none declared.