Mumps vaccine: Canadian Immunization Guide
Key information (refer to text and tables for details)

# What
- Outbreaks of mumps continue to occur in Canada; the majority of outbreak-related mumps cases in Canada in recent years have occurred in young adults aged 15-39 years and the proportion of cases aged 20 years and older has increased.
- Complications such as orchitis and oophoritis are relatively frequent; permanent sequelae like deafness are rare.
- Mumps vaccine is available as measles-mumps-rubella (MMR) or measles-mumps-rubella-varicella (MMRV) vaccine.
- Mumps vaccine effectiveness has been estimated at 62% to 91% for 1 dose and 76% to 95% for 2 doses.
- Reactions to MMR vaccine are generally mild and transient and include pain and redness at the injection site, fever less than 39C, and rash. Reactions to MMRV vaccine include: pain and redness at the injection site and fever less than 39C in 10% or more of vaccine recipients; measles-like, rubella-like or varicella-like rash, swelling at the injection site and fever greater than 39C in less than 10% of vaccine recipients.
- When the first dose is administered to children 12 to 23 months of age as MMRV vaccine, there is a higher risk of fever and febrile seizures in the 7 to 10 days after vaccination when compared to separate administration of MMR and univalent varicella vaccine at the same visit.

# Who
- Mumps-containing vaccine is recommended for routine immunization of children and for immunization of children and adolescents who missed mumps immunization on the routine schedule.
- Mumps-containing vaccine is recommended for susceptible adults born in or after 1970.
- Adults born before 1970 are generally presumed to have acquired natural immunity to mumps; however, susceptible health care workers, travellers to destinations outside of Canada, and military personnel should receive MMR vaccine, regardless of year of birth.

# How
- Routine childhood immunization: 2 doses of any mumps-containing (MMR or MMRV) vaccine. The first dose of mumps-containing vaccine should be administered at 12 to 15 months of age and the second dose at 18 months of age or any time thereafter, but no later than around school entry.
- Children and adolescents who are previously unimmunized: 2 doses of mumps-containing vaccine. MMRV vaccine may be used in healthy children aged 12 months to less than 13 years.
- Susceptible adults born in or after 1970: 1 dose of MMR vaccine. Those who are at the greatest risk of mumps exposure (travellers to destinations outside of Canada, health care workers, students in post-secondary educational settings, and military personnel) should receive 2 doses of MMR vaccine.
- Susceptible health care workers and military personnel born before 1970: 2 doses of MMR vaccine.
- Susceptible travellers to destinations outside of Canada born before 1970: 1 dose of MMR vaccine.
- Susceptible students in post-secondary educational settings born before 1970: 1 dose of MMR vaccine should be considered.

# Why
- Mumps occurs worldwide and outbreaks continue to occur.
- Complications of mumps disease are relatively frequent, although permanent sequelae are rare.
Epidemiology

# Disease description

## Infectious agent
Mumps virus is a member of the Paramyxoviridae family.

## Reservoir
Humans

## Transmission
Mumps virus is transmitted primarily by large droplet spread, as well as by direct contact with infected respiratory droplets or saliva. The incubation period is between 12 and 25 days (average 16 to 18 days). Mumps virus has been isolated from saliva 7 days before to 9 days after the onset of symptoms, with maximum infectiousness between 2 days before to 5 days after onset of symptoms. Infected individuals who are asymptomatic can still transmit mumps to others.

## Risk factors
In general, people who have not had mumps or who have not been vaccinated are at risk of being infected. In Canada, most adults born before 1970 are presumed to have acquired natural immunity to mumps; however, some individuals may not have had mumps disease and may be susceptible. A second dose of mumps vaccine was routinely given in combination with measles and rubella vaccine (MMR) for measles control, beginning in 1996 to 1997. People born between 1970 and 1990 represent a group vulnerable to mumps infection, as these individuals are less likely to have received two doses of mumps-containing vaccine or been alive when the wild virus circulated widely.

## Seasonal and temporal patterns
Historically, the incidence of mumps disease peaked in the spring and winter months in temperate zones. It is now restricted to sporadic cases and outbreaks.

## Spectrum of clinical illness
About 40% of people infected with mumps develop acute parotitis, which is unilateral in about 25% of cases. Non-specific or primarily respiratory symptoms occur in about one-half of infected individuals. Subclinical infection is common. Although complications are relatively frequent, permanent sequelae are rare. Before the widespread use of vaccine, mumps was a major cause of viral meningitis. Mumps meningoencephalitis can, rarely, result in permanent neurologic sequelae, including paralysis, seizures, cranial nerve palsies and hydrocephalus. Permanent deafness may occur, at an estimated rate of 0.5 to 5.0 per 100,000 mumps cases. Orchitis occurs in 20% to 30% of post-pubertal male cases and oophoritis in 5% of post-pubertal female cases. Involvement of the reproductive organs is commonly unilateral; therefore, sterility is rare. Mumps infection in pregnancy has not been associated with congenital malformations, but mumps infection during the first trimester of pregnancy may increase spontaneous abortion.

# Disease distribution

## Global
Mumps occurs worldwide, with cases reported throughout the year and epidemics occurring every 2 to 5 years. Mumps remains endemic in many countries.

## National
Since the authorization of mumps vaccine in Canada in 1969 and the subsequent introduction of a routine two-dose MMR vaccination schedule in 1996/97, the number of reported mumps cases nationally has decreased by more than 99%. The age distribution of mumps in Canada has also changed. The majority of cases during 2014 to 2018 have been observed in the 20 to less than 40 year old age group. During this time period, the highest incidence rates were reported in adults 20 to 24 years (3.8 cases per 100,000 population). Mumps continues to be a cyclical disease in Canada, with outbreaks occurring every few years and otherwise low incidence rates.
Preparations authorized for use in Canada

# Mumps-containing vaccines
- M-M-RII (live attenuated combined measles, mumps and rubella vaccine), Merck Canada Inc. (MMR)
- PRIORIX (live attenuated combined measles, mumps and rubella vaccine), GlaxoSmithKline Inc. (MMR)
- PRIORIX-TETRA (live attenuated combined measles, mumps, rubella and varicella vaccine), GlaxoSmithKline Inc. (MMRV)
- ProQuadTM (live attenuated combined measles, mumps, rubella and varicella vaccine), Merck Canada Inc. (MMRV)
In Canada, mumps vaccine is available only in combination with measles and rubella vaccine (MMR) or measles, rubella and varicella vaccine (MMRV). All vaccines licensed for the prevention of mumps (MMR and MMRV) in Canada contain the Jeryl Lynn attenuated mumps virus strain that belongs to genotype A. In some other countries, measles vaccine alone is given and mumps vaccination is not offered.
For complete prescribing information, consult the product leaflet or information contained within the product monograph available through Health Canada's .
Immunogenicity, efficacy and effectiveness

# Immunogenicity
In clinical studies, a single injection of MMR vaccine induced measles antibodies in 95%, mumps antibodies in 96%, and rubella antibodies in 99% of previously seronegative children.
In 12 month old children, a single dose of MMRV vaccine results in similar seroconversion rates as those achieved after concomitant administration of MMR vaccine and univalent varicella vaccine. A study of children receiving 2 doses of MMRV vaccine during the second year of life noted seropositivity for measles, mumps, rubella and varicella of 99%, 97.4%, 100% and 99.4% respectively by the third year post-vaccination.

# Efficacy and effectiveness
Mumps vaccine effectiveness has been estimated at 62% to 91% for 1 dose and 76% to 95% for 2 doses. Somewhat lower vaccine effectiveness has been observed in outbreak settings, especially when exposures occurred in close-contact settings. Mumps outbreaks have been reported in populations with greater than 95% coverage with single dose mumps-containing vaccine, suggesting that 1 dose of mumps-containing vaccine is not sufficient to prevent mumps outbreaks. In some instances, outbreaks have arisen in settings with high 2 dose coverage. Waning immunity appears to contribute to the risk of mumps in vaccinated individuals.
There are no data regarding the long-term effectiveness of MMRV vaccine.
Recommendations for use

# Children

### Routine schedule
Healthy children (12 months to less than 13 years of age)
For routine immunization of children aged 12 months to less than 13 years, 2 doses of mumps-containing vaccine, using either MMR or MMRV vaccine, should be administered. The first dose of mumps-containing vaccine should be administered at 12 to 15 months of age and the second dose at 18 months of age or any time thereafter, but no later than around school entry.

### Catch-up and accelerated schedules
Children (12 months to less than 13 years of age)
Two doses of mumps-containing vaccine, using either MMR or MMRV vaccine, should be administered to children less than 13 years of age who were not immunized on the routine schedule. For preschool aged children, 2 doses of mumps-containing vaccine should be administered before school entry (4 to 6 years of age). Children who previously received a single dose of MMR vaccine should receive a second dose at least 4 weeks after the first dose. The minimum interval between doses of mumps-containing vaccine is 4 weeks.
Adolescents (13 to less than 18 years of age)
Mumps-susceptible adolescents (refer to  for criteria for immunity) should receive 2 doses of MMR vaccine, given at least 4 weeks apart.

# Adults

## Healthy adults (18 years of age and older)
Mumps-susceptible adults (refer to  for criteria for immunity) should receive 1 or 2 doses of MMR vaccine as appropriate for age and risk factors. If 2 doses are needed, MMR vaccine should be administered with a minimum interval of 4 weeks between doses.

## Routine schedule
Adults born before 1970 are generally presumed to have acquired natural immunity to mumps; however, some of these individuals may be susceptible.
Adults without contraindications, born in or after 1970 who do not meet the definition of mumps immunity (refer to  for criteria for immunity) should be immunized with 1 dose of MMR vaccine.

# High risk individuals

## Health care workers

## Students in post-secondary educational settings
Students born in or after 1970, who do not meet the definition of mumps immunity (refer to  for criteria for immunity) should receive 2 doses of MMR vaccine. In students born before 1970, administration of 1 dose of MMR vaccine should be considered.

## Military personnel
Military personnel, regardless of their year of birth, who do not meet the definition of mumps immunity (refer to  for criteria for immunity) should receive 2 doses of MMR vaccine.

## Travellers

# Susceptibility and immunity
	+ Children 12 months to less than 18 years of age: 2 doses
	+ Adults born in or after 1970: 1 dose,OR
- History of laboratory confirmed infectionOR
- Laboratory evidence of immunityOR
- Born before 1970
- History of laboratory confirmed infectionOR
- Laboratory evidence of immunity
	+ If born in or after 1970: 2 doses
	+ If born before 1970: 1 doseOR
- History of laboratory confirmed infectionOR
- Laboratory evidence of immunity
	+ If born in or after 1970: 2 doses
	+ If born before 1970: consider 1 dose if no documentation of receipt of mumps-containing vaccineOR
- History of laboratory confirmed infectionOR
- Laboratory evidence of immunity
- History of laboratory confirmed infectionOR
- Laboratory evidence of immunity
Mumps-containing vaccine
Immunization against mumps and measles is provided in a combination vaccine (MMR or MMRV). For guidance on measles immunization for travellers refer to Measles Vaccine in Part 4 for additional information.

# Booster doses and re-immunization
Re-immunization with mumps-containing vaccine after age and risk appropriate vaccination is not necessary.

# Post-exposure immunization
Post-exposure vaccination with MMR vaccine should be given to susceptible individuals because exposure may not result in infection, and the MMR vaccine will induce protection against subsequent exposures. There is no evidence of increased risk of adverse reactions from immunization with MMR vaccine if an individual is already immune to one or more components of the vaccine or infected by mumps virus. There are no data on the use of MMRV vaccine in post-exposure situations.

## Outbreak control
The size, scope and duration of mumps outbreaks can be variable and their progression and peak is difficult to predict given delays in reporting, health seeking behaviours, and the relatively long incubation period for the mumps virus. Furthermore, circulation of mumps virus in highly immunized populations may be undetected and determining immunization status of cases and contacts may be challenging in many jurisdictions in Canada due to variability in the availability of comprehensive immunization registries.
The public health response to mumps includes management of cases and contacts and identifying social networks to define the at-risk population when contact follow-up is not feasible; and maintaining/enhancing surveillance for further cases and disease outcomes (e.g., hospitalizations, complications). Generally, a mumps outbreak is controlled by:
- Defining the at-risk population(s) and transmission setting(s)
- Preventing further transmission through isolation of cases and contact education/ awareness
- Vaccination of under-immunized groups
- Good risk communication
In an outbreak setting, implementation of an outbreak dose of MMR vaccine may be considered as a part of the broader outbreak management strategy. In addition, MMR vaccine (up to a third dose) may be considered for close contacts following exposure to a case of mumps in an outbreak setting. However, due to the potential logistical challenges that are associated with program implementation (such as those related to vaccine supply and acquisition costs, vaccine uptake and virus susceptibility determination and the absence of immunization records or information on the exposures), it is important to promptly assess the outbreak characteristics and define the populations that have or may be exposed to the disease.
Implementation of immunization programs early during a mumps outbreak (during the time of rapidly increasing case counts) is important, as early vaccination is likely to be the most effective intervention to control the outbreak. While immunization in later stages of the outbreak (e.g. following the peak of the outbreak) may benefit individuals, its effect at the population-level is uncertain.
Various options for the implementation of an outbreak dose of MMR vaccine are available, including immunization according to time since last dose, setting and level of exposure, and age and risk of complications. Understanding the nature of the outbreak (person-place-time) as well as access to the immunization history of the target group will be critically important for informing the choice and delivery of the outbreak dose strategy, including whether an outbreak dose should be the 1st, 2nd or 3rd dose of mumps-containing vaccine.
For a list of considerations for Mumps Outbreak Management options please see .
The vaccine recommendations and other information provided in the Canadian Immunization Guide are intended to complement and, where applicable, update the  published in 2010, which provide more detailed and comprehensive information on the principles of mumps outbreak management beyond immunization. For further information regarding mumps outbreak control, refer to the Public Health Agency of Canada's (PHAC) .
Vaccination of specific populations

# Persons with inadequate immunization records
Children and adults who are susceptible to mumps, including those lacking adequate documentation of immunization, should be started on an immunization schedule appropriate for their age and risk factors. Mumps-containing vaccine may be given regardless of possible previous receipt of the vaccine because additional adverse events associated with repeated immunization have not been demonstrated. Refer to  in Part 3 for additional information.

# Pregnancy and breastfeeding
Immunity to measles, mumps and rubella should be reviewed in women of reproductive age, and vaccination should be recommended to susceptible non-pregnant women. Women should delay pregnancy by at least 4 weeks following vaccination with MMR vaccine.
MMR and MMRV vaccines are contraindicated in pregnancy because of the theoretical risk to the fetus. However, there is no evidence demonstrating a teratogenic risk from the vaccines and termination of pregnancy should not be recommended following inadvertent immunization with either of these vaccines on the basis of fetal risks following maternal immunization. There was no evidence of Congenital Rubella Syndrome in any of the offspring of 226 women inadvertently vaccinated during pregnancy. In some situations, potential benefits of vaccination with MMR vaccine may outweigh risks, such as during measles or rubella outbreaks, in which case vaccination may be considered based on recommendations from public health officials. Pregnant women who are susceptible to mumps should have vaccination offered post-partum.
Susceptible women who are breastfeeding should be vaccinated with MMR vaccine.

# Patients in health care institutions
Susceptible residents of long-term care facilities should receive measles, mumps and rubella-containing vaccine as appropriate for their age and risk factors. Refer to  in Part 3 for additional information.

# Persons with chronic diseases

## Neurologic disorders
People with conditions such as autism spectrum disorders or demyelinating disorders, including multiple sclerosis, should receive all routinely recommended immunizations, including mumps-containing vaccine.

# Immunocompromised persons
Individuals who are immunocompromised, either due to underlying conditions or immunosuppressive agents, are more susceptible to infections including mumps. They may be more likely to experience more severe disease and complications. The safety and effectiveness of the mumps vaccine is determined by the type of immunodeficiency and degree of immunosuppression.
In general, immunocompromised people should not receive live vaccines because of the risk of disease caused by the vaccine strains. When considering immunization of an immunocompromised person with a live vaccine, approval from the individual's attending physician should be obtained before vaccination. For complex cases, referral to a physician with expertise in immunization or immunodeficiency is advised.

# Household contacts
Susceptible household contacts of immunocompromised people should be considered a priority to receive a mumps-containing vaccine as appropriate for age and risk factors.

# Travellers
Protection against mumps is especially important for people planning travel to destinations outside of Canada. Travellers to destinations outside Canada, born in or after 1970, who do not meet the definition of mumps immunity (refer to  for criteria for immunity) should receive 2 doses of mumps-containing vaccine.
Travellers to destinations outside of Canada, born before 1970, who do not meet the definition of mumps immunity (refer to  for criteria for immunity) should receive 1 dose of MMR vaccine.
Mumps is endemic in many countries. Refer to  for additional information.

# Persons new to Canada
Health care providers who see persons newly arrived in Canada should review the immunization status and update immunization for these individuals as necessary. In many countries outside of Canada, mumps and rubella vaccines are in limited use and measles vaccine alone is given. A Canadian study showed that more than one-third of new immigrants and refugees, particularly women, were susceptible to measles, mumps, or rubella. Refer to  in Part 3 for additional information.

# Workers
It is recommended that all health care workers be immune to mumps. Health care workers, regardless of their year of birth, who do not meet the definition of mumps immunity (refer to  for criteria for immunity) should be vaccinated accordingly so that they have received 2 doses of MMR vaccine. Refer to  in Part 3 for additional information.
Serologic testing
Serologic testing is not recommended before or after receiving mumps-containing vaccine. For further information regarding mumps serology refer to the PHAC .
Administration practices

# Dose and route of administration
Dose
Each dose of mumps-containing vaccine is 0.5 mL.
Route of administration
MMR vaccine should be administered subcutaneously (SC). MMRV vaccine should be administered according to the product monograph.

## Interchangeability of vaccines
On the basis of expert opinion, the MMR vaccines authorized for use in Canada may be used interchangeably. Refer to  for information about interchangeability of MMRV vaccines. Refer to  in Part 1 for additional information.

## Concurrent administration with other vaccines
MMR vaccine may be administered concurrently with, or at any time before or after, non-live vaccines, live oral vaccines, or live intranasal influenza vaccine (LAIV).
MMR vaccine may be administered together with other routinely provided live parenteral vaccines. If not given concomitantly, a minimum interval of 4 weeks is recommended between administration of MMR and other live parenteral vaccines. This recommendation is to address the risk of interference from the vaccine given first on the vaccine given later.
Different injection sites and separate needles and syringes must be used for concomitant parenteral injections. Refer to  in Part 1 for additional information about concomitant administration of mumps-containing vaccine with other vaccines.
Storage and handling requirements
Safety and adverse events

# Common and local adverse events

## Measles-Mumps-Rubella vaccine
Adverse events following immunization with MMR vaccine occur less frequently and are less severe than those associated with natural disease. Adverse reactions are less frequent after the second dose of vaccine and tend to occur only in individuals not protected by the first dose. Six to 23 days after immunization with MMR vaccine, approximately 5% of immunized children experience malaise and fever (with or without rash) lasting up to 3 days. Parotitis, rash, lymphadenophy, and joint symptoms also occur occasionally after immunization with MMR vaccine. There are no known serious vaccine safety concerns following the administration of a third dose of MMR vaccine.

## Measles-Mumps-Rubella-Varicella vaccine
Pain and redness at the injection site or fever less than 39C occur in 10% or more of vaccine recipients. Rash, including measles-like, rubella-like and varicella-like rash, as well as swelling at the injection site and fever greater than 39C occur in 1% to less than 10% of vaccine recipients. As varicella-like rashes that occur within the 2 weeks after immunization may be caused by wild-type virus (varicella virus circulating in the community), health care providers should obtain specimens from the vaccine recipient to determine whether the rash is due to natural varicella infection or to the vaccine-derived strain.

## Rubella-containing vaccines
Acute transient arthritis or arthralgia may occur 1 to 3 weeks after immunization with rubella-containing vaccine. It lasts for about 1 to 3 weeks, and rarely recurs. It is more common in post-pubertal females, among whom arthralgia develops in 25% and arthritis in 10% after immunization with rubella-containing vaccine. There is no evidence of increased risk of new onset chronic arthropathies.

# Less common and serious or severe adverse events
Serious adverse events are rare following immunization and, in most cases, data are insufficient to determine a causal association. Anaphylaxis following vaccination with MMR or MMRV vaccine may occur but is very rare.

## Immune Thrombocytopenic Purpura
Rarely, Immune Thrombocytopenic Purpura (ITP) occurs within 6 weeks after immunization with MMR or MMRV vaccine. In most children, post-immunization thrombocytopenia resolves within 3 months without serious complications. In individuals who experienced ITP with the first dose of MMR or MMRV vaccine, serologic status may be evaluated to determine whether an additional dose of vaccine is needed for protection. The potential risk to benefit ratio should be carefully evaluated before considering vaccination in such cases.

## Encephalitis
Encephalitis has been reported in association with administration of measles vaccine in approximately 1 per million doses distributed in North America, which is much lower than the incidence observed with natural measles disease (1 per 1,000 cases).

## Febrile seizures
Between the ages of 12 to 23 months, when the first dose of vaccine for measles and varicella is administered as MMRV vaccine, there is a higher risk of fever and febrile seizures in the 7 to 10 days after vaccination when compared to separate administration of MMR and varicella vaccine at the same visit. For additional information about febrile seizures following the administration of MMRV vaccine, refer to  in Part 4.

# Other safety issues
In the mid to late 1990s, researchers from the United Kingdom reported an association between MMR vaccine and inflammatory bowel disease, and MMR vaccine and autism. Rigorous scientific studies and reviews of the evidence have been done worldwide, and there is now considerable evidence to refute those claims. In 2010, the original study suggesting a link between the MMR vaccine and autism was found to be fraudulent and was retracted.

# Guidance on reporting Adverse Events Following Immunization (AEFI)
To ensure the ongoing safety of vaccines in Canada, reporting of AEFIs by vaccine providers and other clinicians is critical, and in some jurisdictions, reporting is mandatory under the law.
Vaccine providers are asked to report AEFIs through local public health officials and to check for specific AEFI reporting requirements in their province or territory. In general, any serious or unexpected adverse event felt to be temporally related to vaccination should be reported. The following AEFIs in particular, should be reported:
- Febrile seizures within 30 days after vaccination with MMR or MMRV vaccine.
- Varicella that is moderate (50 to 500 lesions) or severe (more than 500 vesicular lesions or associated complications or hospital admission) and occurs 7 to 21 days after vaccination with MMRV vaccine.
- Any serious or unexpected adverse event temporally related to vaccination. An unexpected AEFI is an event that is not listed in available product information but may be due to the immunization, or a change in the frequency of a known AEFI.

# Contraindications and precautions
MMR and MMRV vaccines are contraindicated in persons with a history of anaphylaxis after previous administration of the vaccine and in persons with proven immediate or anaphylactic hypersensitivity to any component of the vaccine, with the exception of egg allergy. Refer to  in Part 1 for a list of vaccines authorized for use in Canada and their contents.
In situations of suspected hypersensitivity or non-anaphylactic allergy to vaccine components, investigation is indicated which may involve immunization in a controlled setting. Consultation with an allergist is advised.
Although the measles and mumps components of MMR and MMRV vaccines are produced in chick embryo cell culture and may contain traces of residual egg and chicken protein, the trace amount of egg or chicken protein in the vaccine appears to be insufficient to cause an allergic reaction in egg-allergic individuals. Skin testing is not recommended prior to vaccination as it does not predict reaction to the vaccine. MMR or MMRV vaccine can be administered in the routine manner to people who have a history of anaphylactic hypersensitivity to hens' eggs. Prior egg ingestion is not a prerequisite for immunization with egg protein-containing vaccine. For all vaccines, immunization should always be performed by personnel with the capability and facilities to manage adverse events post-vaccination. Refer to  in Part 2 for additional information.
Children with a known or suspected family history of congenital or hereditary immunodeficiency that is a contraindication to vaccination with live vaccine should not receive live vaccines unless their immune competence has been established. Refer to  in Part 3 for additional information.
MMR and MMRV vaccines are contraindicated during pregnancy because of the theoretical risk to the fetus. Refer to  in Part 3 for additional information.
Measles-containing vaccines are contraindicated in individuals with active, untreated tuberculosis (TB) as a precautionary measure. Although TB may be exacerbated by natural measles infection, there is no evidence that measles-containing vaccines have such an effect. Nonetheless, anti-tuberculous therapy for active TB disease is advisable before administering measles-containing vaccines and it may be prudent to avoid live viral vaccines in those with active TB disease until treatment is underway. Consultation with an expert in infectious diseases is recommended.
A history of febrile seizures or a family history of seizures is not a contraindication for the use of MMRV vaccine.
Administration of MMR or MMRV vaccine should be postponed in persons with a severe acute illness. Persons with a minor acute illness, with or without fever, may be vaccinated.
It is recommended to avoid the use of salicylates (medications derived from salicylic acid, such as acetylsalicylic acid ) for 6 weeks after immunization with MMRV vaccine because of an association between wild-type varicella, salicylate therapy and Reye's syndrome.
Other considerations

# Drug interactions

## Systemic antiviral therapy
Systemic antiviral therapy (such as acyclovir, valacyclovir, famciclovir) should be avoided in the peri-immunization period, as it may affect the reproduction of the vaccine virus and consequently may reduce the efficacy of varicella-containing vaccine such as MMRV. On the basis of expert opinion, it is recommended that people taking long-term antiviral therapy should discontinue these drugs, if possible, from at least 24 hours before administration of MMRV vaccine and should not restart antiviral therapy until 14 days after vaccine administration.

## Tuberculin skin testing or Interferon Gamma Release Assay
The measles component in measles-containing vaccines can temporarily suppress tuberculin reactivity, resulting in false-negative results. If tuberculin skin testing or an interferon gamma relase assay (IGRA) test is required, it should be done on the same day as immunization or delayed for at least 4 weeks after measles vaccination. Vaccination with measles-containing vaccine may take place at any time after tuberculin skin testing has been performed and read.

## Human immunoglobulin or other blood products
Passive immunization with human Ig or receipt of most other blood products can interfere with the immune response to MMR and MMRV vaccines. Refer to  in Part 1 for recommended intervals between the administration of Ig preparations or other blood products and MMR and MMRV vaccines.
Chapter revision process
This chapter has been updated in accordance with the National Advisory Committee on Immunization Statement (NACI): . The recommendations on mumps outbreak management provided in this chapter and the statement are based on the best current available scientific knowledge and are intended to complement and, where applicable, update the  published in 2010.