Introduction
MMR vaccine is given for protection against 3 common childhood viral diseases namely measles, mumps & rubella (German Measles).
MMR vaccine is available as a bulb containing lyophilized powder. The diluent is distilled water or normal saline & is available separately in an ampoule. MMR is a live viral vaccine. It is available as a mono dose or as a multidose bulb.
It is stored in a refrigerator. The vaccine stocks are stored frozen in the freezer compartment. Working stock can be stored at 2-8 degree C in the lower rack. No vaccine is stored in the door of the refrigerator. The diluent is also stored at 2-80C.
MMR vaccine is prepared by adding diluent in the powder. Once prepared it should be used immediately. At the most, it can be kept for 2-3 hours that too at 2-8 degree C after which it is discarded. Like the measles vaccine, the MMR vaccine does not have preservatives, hence the growth of pathogens can occur after reconstitution. Such a vaccine if not stored properly or used beyond 2-3 hours of reconstitution can lead to toxic shock syndrome as seen with the measles vaccine.
MMR vaccine is given subcutaneously using 26 no. needle, by raising a fold of skin with one hand & injecting the vaccine beneath it. It is given either over the anterolateral aspect of the thigh or over the arm. The efficacy of the vaccine remains the same even if given intramuscularly by mistake; the gluteal region should not be used for any injection in children, especially below 2 years of age.
Usefulness Of MMR Vaccine
MMR vaccine is not an EPI vaccine as per Govt. of India. Indian Academy of Pediatrics & most of the pediatricians strongly recommend this vaccine as a routine for all children. There are some states in India (like Delhi) where pilot projects of giving MMR routinely as a part of EPI vaccines have been started. Hopefully, it will become a part of the national schedule soon. It is essential for children as the measles part of MMR will boost up the immunity against measles induced by the previous measles vaccine. Mumps is a common cause of morbidity in children with occasional chances of complications like encephalitis & pancreatitis. But its most important silent complications are oophoritis & orchitis. This will manifest as primary sterility in adulthood. Rubella or German measles though a benign disease can lead to congenital rubella syndrome if it occurs during pregnancy. Such a child will have cataracts, deafness, congenital heart disease, microcephaly, mental retardation, hepatitis & many other complications. Hence MMR vaccine is essential.
MMR Vaccine 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 the development of autism.
Usefulness and The Chances of Aseptic Meningitis
3 cases of Aseptic meningitis were reported following the use of Urabe MMR from Canada in 1987. The Urabe MMR was recalled from Canada in 1988. Urabe MMR was introduced in the 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 an active surveillance program started in the UK. The risk of aseptic meningitis was estimated to be 1 in 143,000. This led to the 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 the MMR vaccine is 3-4 times more costly than the Urabe strain MMR. In the 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 the continued use of this vaccine in India.
MMR Vaccine - Schedule
Two doses are recommended one at the age of 12-15 months and second at school entry (4-6 years) or at any time 8 weeks after the first dose. The second dose of the MMR vaccine is to protect children failing to seroconvert against primarily Mumps and less commonly against Rubella (primary vaccine failures).
A Single-dose of MMR vaccine has excellent efficacy with> 95% protective titers, especially against measles & rubella. Breakthrough mumps can occur in spite of vaccination. A booster of MMR will further increase its efficacy as discussed before.
Delayed dose: Measles mostly occurs till 5 - 15 years of age. Mumps & rubella can occur at any age. Hence if a patient comes late he can be given MMR till 5-15 years of age after which the MR (Mumps, Rubella) vaccine can be given. As the MR vaccine is not available MMR can be given even to older individuals as no harm is done by the measles part. If a patient has already developed measles, mumps & rubella he does not need a vaccine against them.
Use with other vaccines: Yes, MMR can be given simultaneously with other vaccines. In fact, it can be given along with 1st booster dose of OPV, DPT vaccine & Hib or with the Varicella vaccine. A combination vaccine containing MMR + varicella is available. Like with measles, the MMR vaccine can lead to temporary suppression of immunity for 4-6 weeks. Hence BCG should not be given with MMR & no other vaccine should be given within 4-6 weeks of the MMR vaccine.
MMR Vaccine - Side Effects
MMR vaccine is a very safe vaccine. If at all, it leads to mild pain, swelling, induration, or fever. It is seen in less than 10% of patients, is transient & mild, lasts for <24 hours & responds well to paracetamol. It can occur from the day of injection until 5-7 days. Sometimes a patient can develop a measles-like infection with a cough, cold, red eyes & rash over the skin. Again it lasts for 2-5 days & is self-limiting. Contrary to belief, the MMR vaccine does not lead to SSPE. There are 2 complications that could prove fatal and are discussed below:
Anaphylaxis is seen in patients with egg allergy as MMR (like measles vaccine) is grown in chick embryo culture. In patients, with mild egg allergy, it leads to less severe reactions like angioedema, puffiness, urticaria, anaphylactoid reactions. In patients with severe allergies, it can lead to frank anaphylaxis. In cases of severe egg allergy, measles & MMR vaccines are contraindicated. In the case of mild egg allergy, measles or MMR vaccines can be given but with strict medical supervision and all the measures of resuscitation & drugs kept ready should the patient develop a reaction.
Toxic shock syndrome (TSS) is an unfortunate but avoidable reaction of the MMR vaccine. MMR vaccine does not have a preservative. Hence, once reconstituted it should not be kept beyond 2-3 hours & that too it should be kept at 2-8°C. If it is not stored properly or is used after 2-3 hours there are chances of growth of pathogens, the most important being staphylococci. When this happens, the staphylococcal toxin formed will lead to fever, diarrhea, vomiting, blood in stools, DIC, shock & ultimately death. This usually follows the use of multidose bulbs where the balance doses are not kept properly or not used in time. Obviously, it is totally avoidable by using properly stored vaccines and using the vaccine immediately after reconstitution. This is the reason why mono doses are preferred over multidose bulbs.
MMR Vaccine - Contraindications
True & severe egg allergy is the contraindication to use Measles or MMR vaccine. A sick patient should receive any vaccine after he recovers from his illness. If a patient has shown severe adverse effects following any vaccine he should not receive the same vaccine again & this is true for the measles & MMR vaccine too.