As they are live vaccines, you don’t usually want to give them to anyone who might be immunocompromised. And since some conditions that cause immune system problems can run in families, if there is a family history of these conditions, you want to make sure your child doesn’t have one before they are vaccinated.
(g) family history of congenital or hereditary immunodeficiency in first-degree relatives (e.g., parents and siblings), unless the immune competence of the potential vaccine recipient has been substantiated clinically or verified by a laboratory.
General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP)
Fortunately, these types of severe immune problems are rare.
They might include:
Severe antibody deficiencies (e.g., X-linked agammaglobulinemia and common variable immunodeficiency)
Partial defects (e.g., most patients with DiGeorge syndrome, Wiskott-Aldrich syndrome, ataxia- telangiectasia)
Phagocytic deficiencies that are undefined or accompanied by defects in T-cell and NK cell dysfunction (such as a Chediak-Higashi syndrome, Leukocyte Adhesion Deficiency [LAD], and myeloperoxidase deficiency)
Talk to your pediatrician if your child has a first degree relative with one of these conditions, before they get their MMR or chicken pox vaccines.
Still, by twelve months, infants with a severe congenital or hereditary immunodeficiency or any other severe immunodeficiency will almost certainly have symptoms already.
Most children, for example, had been diagnosed with severe combined immunodeficiency (SCID), in early infancy when they have severe and life-threatening infections and failure to thrive.
And most newborns in the United States are now screened for SCID as a part of their routine newborn screening test, and can be diagnosed and treated before they have symptoms! That’s also long before they might be due for their MMR or chicken pox vaccines.
So, if your child has a family history of congenital or hereditary immunodeficiency, and it is in a first-degree relative, but has no symptoms themselves, then they can get safely vaccinated on schedule.
“Before a vaccine became available in 1963, measles was a rite of passage among American children. A red rash would spread over their bodies. They would develop a high fever. Severe cases could cause blindness or brain damage, or even death.”
CDC says measles almost eliminated in U.S.
Instead, most people develop 10 days of measles symptoms, including a high fever, cough, runny nose, watery eyes, and a rash. Photophobia, irritability, sore throat, headache, and abdominal pain are other symptoms that children with measles might have.
“From 1964 through 1971, 16.7% of the death certificates reviewed noted some underlying pathologic condition.”
Roger Barkin, MD on Measles mortality. Analysis of the primary cause of death.
It is most often children, typically young children, without any medical problems who die.
In the post-vaccination era, no one would be expected to die with measles, but those with immune system problems sometimes do, as most others are vaccinated and protected. As vaccinated rates drop though, even otherwise healthy children and adults can once again die of measles.
“Complications were reported in 672 (9.8%) cases, including otitis media in 318 (4.6%) cases, pneumonia in 178 (2.6%), diarrhea in 171 (2.5%), and encephalitis in five (0.1%). Nine hundred thirteen patients (13.3%) were hospitalized, and 10 measles-associated fatalities were reported (case-fatality rate: 1.5 deaths per 1000 reported cases). Eight of the deaths were reported in children less than 5 years of age, all of whom were unvaccinated. None had a reported underlying illness or immunodeficiency. Most deaths have been attributed to pneumonia.”
Measles — United States, First 26 Weeks, 1989
Probably not, but from 1989 to 1991 there were at least 123 measles deaths across the United States, even after measles had been declining for years with the introduction of the measles vaccine in the 1960s. Most of the deaths were otherwise healthy, without underlying medical problems.
Because we don’t typically hear any details about measles deaths, including the almost 90,000 measles deaths that continue to occur around the world each year, most people likely assume that measles only kills in third world countries, where kids are already sick or malnourished. Of course, that wouldn’t explain how over one hundred people died with measles in Europe over the past few years…
Still think that measles isn’t deadly?
Tragically, there are plenty of stories (although most are never reported in the news and we don’t hear about them) and case reports that will prove you wrong:
Olivia Dahl died with measles when she was 7-years-old (1962)
an unvaccinated 3-year-old died in Maricopa County (1970)
a 13-year-old girl who had previously been vaccinated with one of the first inactivated measles vaccines which were found to be ineffective and were replaced with the newer live vaccines died in Michigan (1978)
a 9-month-old died in Chicago (1990)
an unvaccinated 13-year-old died in Kansas (1990)
Tammy Bowman, an 11-year-old unvaccinated girl died in Michigan (1990)
an unvaccinated 13-year-old became the first person in the UK to die with measles in 14 years (2006)
a 14-year-old died of Subacute Sclerosing Panencephalitis (SSPE), a late complication of a natural measles infection (2015)
a 16-year-old who had received a heart transplant when she was 2-years-old died in France (2018)
an unvaccinated toddler in Jerusalem (2018)
Measles as a rite of passage?
“We baby boomers were apparently the last generation whose doctors, and therefore parents, accepted the measles as just one more annoying rite of passage of childhood that also happened to prime the immune system and provide lifelong immunity. Medical texts prior to the advent of the vaccine described measles as a benign, selflimiting (sic) childhood infectious disease that posed little risk to the average well-nourished child.”
Darrerl Crain, DC on The Great Measles Misunderstanding
While early pediatric textbooks did a great job describing the symptoms of measles, they also did a great job of documenting that measles was never a benign disease, something anti-vaccine folks still misunderstand because vaccines can do such a good job controlling the disease.
Do benign, self-limiting childhood infections diseases kill hundreds of children every year?
Measles as a rite of passage is something we don’t want to have to go back to. It was a rite of passage that was endured because there was no other choice.
Breaking News – the inquiry into the deaths of two infants a few months ago continues to be delayed, all immunizations were halted by mistake, not just MMR and kids are starting to get vaccine preventable diseases (see below).
Many people remember that two young children died in Samoa in early July, shortly after getting an MMR vaccine.
Both incidents happened on the same day in the same hospital on the island of Savai’i.
“Until the investigations have been completed and reported on we cannot say what did happen.
However, given the batch of vaccine involved had been in use in that country since August last year, and given the same batch of vaccine has been used in South American countries and the Caribbean island nations without incident, it seems unlikely that there was anything wrong with the vaccine.
The reports from the parents of the children affected on Friday indicate the reactions occurred within minutes after vaccination. This would preclude a response to the vaccine viruses as this takes at least a week. While anaphylaxis occurs within minutes and can be fatal when not treated the odds of seeing this twice in a day at the same place, given a chance of 1 in a million doses, is literally astronomical.”
Dr. Helen Petousis Harrison on What happened in Samoa?
And while many people have speculated on what had happened, we didn’t get much new information until the Attorney General Lemalu Herman Retzlaff issued a press statement:
It can be confirmed that one of the nurses involved with the vaccination injections of the two babies who passed away 6th July 2018, was charged by police on Saturday 4th August 2018. She is set to appear in Court 14th August 2018, where the charges will be confirmed publicly.
According to AG Lemalu, “the file was referred to this office for advice last week, after swift and hard-working investigations by the CID section of the Ministry of Police both in Apia and Savaii, which is to be commended.”
“And the decision to charge was thereafter supported by advice; and it is also confirmed by Police, that investigations are still active and on-going.”
Both nurses have now been charged and both have entered not guilty pleas to charges of manslaughter, negligence and conspiracy to defeat the course of justice.
A trial is set for January 21, 2019.
Apparently though, an ongoing investigation into the deaths of the two toddlers that had been adjourned until September 12, as they were still waiting on the the post mortem reports from the pathologist in Australia, has been suspended even further.
“The inquiry into the deaths of two babies in Samoa has been suspended until further information is available from post mortem results”
Why were the nurses charged with manslaughter? Many think the main issue is that the nurses continued to use the MMR vaccine even after the first baby died.
“This particular vaccine batch lot arrived to Samoa in August 2017 and has been in use since then. The same vaccine batch lot used in Samoa is also in use in a number of South American and Caribbean countries (Belize, Ecuador, St. Vincent, Trinidad Tobago, Chile, Aruba, Dutch Antilles, St. Kitts & Nevis and Cuba) with no reports of adverse events from those countries.”
“To our community, Andrew Wakefield is Nelson Mandela and Jesus Christ rolled up into one.”
J. B. Handley
He is the guy who published the 1998 paper in Lancet in the UK that started folks thinking that the MMR vaccine is somehow associated with autism.
In 1998, a major medical journal based in the UK, The Lancet, published a report headed by Andrew Wakefield, who was at that time a gastroenterological surgeon and medical researcher. The report implied a causal link between the measles, mumps, and rubella (MMR) vaccine and the development of autism combined with IBD in children, which Wakefield described as a new syndrome he named “autistic entercolitis”.
Andrew Wakefield’s Harmful Myth of Vaccine-induced “Autistic Enterocolitis”
But he didn’t actually say that the MMR vaccine caused autism in that paper, did he?
If not for the press conference, which in itself was unusual, and all of the media attention over the next few years, his small study, which was “essentially a collection of 12 clinical anecdotes,” would have gone nowhere.
But there was no “Wakefield Factor” on immunization rates in the UK, was there? Didn’t measles cases continue to go down in the 10 years after his Lancet paper was published?
Despite the heroic efforts of some folks to manipulate the data, it is clear that MMR vaccination rates dropped and measles cases jumped in the years after Wakefield’s MMR scare.
But even if his paper scared people away from vaccinating and protecting their kids, he was never really found guilty of fraud, was he?
How do you define fraud?
“The Office of Research Integrity in the United States defines fraud as fabrication, falsification, or plagiarism.13 Deer unearthed clear evidence of falsification. He found that not one of the 12 cases reported in the 1998 Lancet paper was free of misrepresentation or undisclosed alteration, and that in no single case could the medical records be fully reconciled with the descriptions, diagnoses, or histories published in the journal.
Who perpetrated this fraud? There is no doubt that it was Wakefield. Is it possible that he was wrong, but not dishonest: that he was so incompetent that he was unable to fairly describe the project, or to report even one of the 12 children’s cases accurately? No.”
Fiona Godlee on Wakefield’s article linking MMR vaccine and autism was fraudulent
But those charges from the General Medical Council were later all overturned, weren’t they?
While charges against John Walker-Smith, a co-author of Wakefield’s study, were dropped on appeal, that doesn’t exonerate Wakefield in anyway. Remember, John Walker-Smith was actually against blaming the MMR vaccine and unlike Wakefield, he and another co-author actually published their own press release stating continued support of the use of the MMR vaccine.
But the other coauthors have stood by the results of the paper, haven’t they?
“We wish to make it clear that in this paper no causal link was established between MMR vaccine and autism as the data were insufficient. However, the possibility of such a link was raised and consequent events have had major implications for public health. In view of this, we consider now is the appropriate time that we should together formally retract the interpretation placed upon these findings in the paper, according to precedent.”
Retraction of an Interpretation
They stood by the idea that it is important that research be done so that gastrointestinal problems in autistic children can be recognized and treated. Almost all of them retracted Wakefield’s interpretation of the paper though.
Yeah, but other studies have proven Wakefield to be right though, haven’t they?
No, they haven’t. In fact, other labs could not even replicate Wakefield’s original study.
But Wakefield’s Lancet paper wasn’t retracted because it’s findings were wrong…
Yes it was!
“Following the judgment of the UK General Medical Council’s Fitness to Practise Panel on Jan 28, 2010, it has become clear that several elements of the 1998 paper by Wakefield et al are incorrect, contrary to the findings of an earlier investigation. In particular, the claims in the original paper that children were “consecutively referred” and that investigations were “approved” by the local ethics committee have been proven to be false. Therefore we fully retract this paper from the published record.”
Retraction—Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children
Their false narratives and myths attempt to rewrite history and make you forget that he doesn’t just scare parents away from vaccinating and protecting their kids, he hurts autistic kids and their families.
These CDC reports should even take away any last idea that they are.
If there was any association with vaccines, then why are autism rates so widely different in the 11 states that are tracked by ADDM?
Are immunization rates different in those states?
Autism and Developmental Disabilities Monitoring (ADDM) Network
Anyone who has read the latest report on autism rates understands that it “is not a representation of autism in the United States as a whole, but is instead an in-depth look at the 11 communities in the ADDM Network.”
Those communities have changed for each report, but this time they were in Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin.
Even then, the ADDM Network doesn’t look at all of the children in those states. They are mostly looking at children near large institutions that are hosts for the ADDM Network, such as the University of Arkansas for Medical Sciences, Johns Hopkins University, and Rutgers University, etc.
The 325,483 8-year-olds in the latest ADDM Network report were born in 2006 and live in:
part of Maricopa County in metropolitan Phoenix, Arizona
75 counties in Arkansas
Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, and Jefferson counties in Colorado
Clayton, Cobb, DeKalb, Fulton, and Gwinnett counties in Georgia
Baltimore County, Maryland
parts of two counties (Hennepin and Ramsey) including the large metropolitan cities of Minneapolis and St. Paul, Minnesota
Franklin, Jefferson, St. Charles, St. Louis, and St. Louis City counties in Missouri
Essex, Hudson, Union, and Ocean counties in New Jersey
Alamance, Chatham, Forsyth, Guilford, Orange, and Wake counties in North Carolina
Bedford, Cheatham, Davidson, Dickson, Marshall, Maury, Montgomery, Rutherford, Robertson, Williamson, and Wilson counties in Tennessee
Dane, Green, Jefferson, Kenosha, Milwaukee, Ozaukee, Racine, Rock, Walworth, and Waukesha counties in Wisconsin
“Autism prevalence among black and Hispanic children is approaching that of white children,” said Dr. Stuart Shapira, associate director for science at the CDC’s National Center on Birth Defects and Developmental Disabilities. “The higher number of black and Hispanic children now being identified with autism could be due to more effective outreach in minority communities and increased efforts to have all children screened for autism so they can get the services they need.”
It shows that “there continue to be many children living with ASD who need services and support, now and as they grow into adolescence and adulthood.”
Immunization Rates and the Autism and Developmental Disabilities Monitoring Network
It also helps to dispell any last ideas that vaccines are associated with autism…
Just look at the immunization rates in the ADDM Network counties (4 doses of DTaP, 3 doses of IPV, one dose of MMR, 3 doses of Hib, 3 doses of HepB, 1 dose of Varicella, 4 doses of Prevnar, flu shot, and 1 dose of HepA by age 36 months) and compare them to the autism rates in those same counties.
If vaccines were associated with autism, what should you see? Higher rates of autism in the areas with the highest immunization rates. You don’t see that in any of this data though, do you?
The counties in New Jersey, with the highest rates of autism, have good immunization rates, but they aren’t much different from the immunization rates in Colorado counties or Arizona counties with much lower autism rates.
Some other things we know about vaccines and the latest autism report?
in 2006, when those kids were born, New Jersey had one of the lowest rates for getting newborns a hepatitis B shot on their first day, as recommended, at just 23%. Arizona, with a much lower rate of autism, did much better, getting 65% of newborns their birth dose of hepatitis B vaccine on time. In fact, Maricopa County had one of the highest rates, at 71%.
fewer than half of their mothers likely received a flu shot during their pregnancy, even though they had been recommended since the 1990s
extremely few of their mothers received a Tdap vaccine during their pregnancy, as this didn’t become a routine recommendation until 2011
Does any of this surprise you?
How can vaccines be associated with autism, when counties that have higher immunization rates have lower rates of autism?
What to Know About Vaccines and the Latest Autism Prevalence Report
The latest Autism and Developmental Disabilities Monitoring (ADDM) Network report on autism prevalence from the CDC shows a rate that has increased to 1 in 59 children. And as county level trends in vaccination coverage show no correlation to those autism prevalence rates, folks will hopefully stop trying to associate vaccines with autism.
More on Vaccines and the Latest Autism Prevalence Report
ITP is an abbreviation for idiopathic thrombocytopenic purpura.
It is a condition in which our platelets get destroyed, leading to excessive bruising and bleeding, since platelets are needed for normal blood clotting.
What Causes ITP?
To understand what causes ITP, it is important to know it is also often referred to as immune thrombocytopenic purpura, because it is typically the cells of our own immune system that destroys our platelets.
Well, that’s where the idiopathic part comes in.
We don’t know why people develop ITP, although classically, ITP is thought to follow a viral infection, including Epstein-Barr virus (mono), influenza, measles, mumps, rubella, and varicella (chicken pox). ITP has also been associated with many other viral infections, from Dengue fever to Zika.
“Often, the child may have had a virus or viral infection approximately three weeks before developing ITP. It is believed that the body’s immune system, when making antibodies to fight against a virus, “accidentally” also made an antibody that can stick to the platelet cells. The body recognizes any cells with antibodies as foreign cells and destroys them. Doctors think that in people who have ITP, platelets are being destroyed because they have antibodies.”
These children with ITP, usually under age 5 years, develop symptoms a few days to weeks after their viral infections. Fortunately, their platelet counts usually return to normal, even without treatment, within about 2 weeks to 6 months. Treatments are available if a child’s platelet count gets too low though.
Can Vaccines Cause ITP?
The measles vaccine is the only vaccine that has been clearly associated with ITP.
“The available data clearly indicate that ITP is very rare and the only vaccine for which there is a demonstrated cause-effect relationship is the measles, mumps and rubella (MMR) vaccine that can occur in 1 to 3 children every 100,000 vaccine doses.”
Cecinati on Vaccine administration and the development of immune thrombocytopenic purpura in children
Even then though, the risk of ITP after a measles containing vaccine, like MMR or ProQuad, is much less than after getting a natural measles infection, so worry about ITP is a not a good reason to skip or delay getting vaccinated.
What about other vaccines?
There is no good evidence that other vaccines, including the chicken pox vaccine, DTaP, hepatitis B vaccine, or flu vaccine, etc., cause ITP.
What about Gardasil? ITP is listed in the package insert as an adverse reaction for Gardasil, but only in the postmarketing experience section, so it does not mean that the vaccine actually caused the reaction, just that someone reported it.
Several large studies have actually been done that found no increased risk for ITP after getting vaccinated with Gardasil.
What to Know About Vaccines and ITP
Although measles containing vaccines can rarely cause ITP, vaccines prevent many more diseases that can cause ITP.
“Measles is so contagious that if one person has it, 90% of the people close to that person who are not immune will also become infected.”
CDC on Transmission of Measles
Unlike measles, which is so contagious that you can get it if you are simply in the same room with someone that is sick, mumps typically requires prolonged, close contact.
“When you have mumps, you should avoid prolonged, close contact with other people until at least five days after your salivary glands begin to swell because you are contagious during this time. You should not go to work or school. You should stay home when you are sick with mumps and limit contact with the people you live with; for example, sleep in a separate room by yourself if you can.”
CDC on Mumps Outbreak-Related Questions and Answers for Patients
How do you get mumps?
Since the virus spreads through saliva and mucus, you can get sick if you are in close contact with someone with mumps and they:
cough or sneeze
use a cup or eating utensil that you then use
touch an object or surface that you then touch (fomites)
And like many other vaccine-preventable diseases, people with mumps are usually contagious just before they begin to show symptoms.
“The mumps virus replicates in the upper respiratory tract and spreads through direct contact with respiratory secretions or saliva or through fomites. The risk of spreading the virus increases the longer and the closer the contact a person has with someone who has mumps.”
CDC on Mumps for Healthcare Providers
The need for prolonged, close contact is likely why most outbreaks these days are on college campuses.
Is Your Child Protected Against the Mumps?
The MMR vaccine protects us against mumps – and measles and rubella.
One dose of MMR is 78% effective at preventing mumps, while a second dose increases that to 88%. Unfortunately, that protection can decrease over time.
Kids get their first dose of MMR when they are 12 to 15 months old. While the second dose of MMR isn’t typically given until just before kids start kindergarten, when they are 4 to 6 years old, it can be given earlier. In fact, it can be given anytime after your child’s first birthday, as long as 28 days have passed since their first dose.
“Evidence of adequate vaccination for school-aged children, college students, and students in other postsecondary educational institutions who are at risk for exposure and infection during measles and mumps outbreaks consists of 2 doses of measles- or mumps-containing vaccine separated by at least 28 days, respectively. If the outbreak affects preschool-aged children or adults with community-wide transmission, a second dose should be considered for children aged 1 through 4 years or adults who have received 1 dose. In addition, during measles outbreaks involving infants aged <12 months with ongoing risk for exposure, infants aged ≥6 months can be vaccinated.”
CDC on Prevention of Measles, Rubella, Congenital Rubella Syndrome, and Mumps, 2013: Summary Recommendations of the Advisory Committee on Immunization Practices
And although it won’t count as their first dose, in special situations, kids can get an early MMR once they are six months old.
What to Do If Your Unvaccinated Child Is Exposed to Mumps
To be considered fully vaccinated and protected against mumps, kids need two doses of MMR – one at 12 to 15 months and another when they are 4 to 6 years.
“Although mumps-containing vaccination has not been shown to be effective in preventing mumps in persons already infected, it will prevent infection in those persons who are not yet exposed or infected. If persons without evidence of immunity can be vaccinated early in the course of an outbreak, they can be protected prior to exposure.”
Unfortunately, neither a post-exposure dose of MMR nor immune globulin work to prevent mumps after you are already exposed. They should still get an MMR though, as it will provide immunity against measles and rubella, and mumps if they don’t get a natural infection.
“Persons who continue to be exempted from or who refuse mumps vaccination should be excluded from the school, child care, or other institutions until 21 days after rash onset in the last case of measles.”
Manual for the Surveillance of Vaccine-Preventable Diseases
Unvaccinated kids who are exposed to mumps will likely need to be quarantined, as you watch for signs and symptoms of measles developing over the next 12 to 25 days.
If your exposed child develops mumps, be sure to call your health care provider before going in for a visit, so that they can be prepared to see you and so you don’t expose other people to mumps. Your child with suspected mumps should be wearing a mask before going out in public and if possible, will be put in a negative pressure room in the emergency room or doctor’s office.
It is very important to understand that simply wearing a mask doesn’t eliminate the risk that your child with mumps could expose others, it just reduces the risk. You still want to avoid other people!
What to Do If Your Vaccinated Child Is Exposed to Mumps
If your fully vaccinated child is exposed to mumps, does that mean you are in the clear?
Again, it depends on what you mean by fully vaccinated.
It also depends on what you mean by exposed. Is it someone in the same school that your child has had no real contact with or a sibling that he is around all of the time?
And is your child fully vaccinated for his age or has he had two doses of MMR?
Since kids get their first dose of MMR at 12 to 15 months and the second when they are 4 to 6 years old, it is easy to see that many infants, toddlers and preschoolers who are following the immunization schedule are not going to be fully vaccinated against mumps, even if they are not skipping or delaying any vaccines.
“In the case of a local outbreak, you also might consider vaccinating children age 12 months and older at the minimum age (12 months, instead of 12 through 15 months) and giving the second dose 4 weeks later (at the minimum interval) instead of waiting until age 4 through 6 years.”
Ask the Experts about MMR
In most cases, documentation of age-appropriate vaccination with at least one dose of MMR is good enough protection. That’s because the focus in controlling an outbreak is often on those folks who don’t have any evidence of immunity – the unvaccinated.
And one dose of MMR is about 78% effective at preventing mumps infections. A second dose does increase the vaccine’s effectiveness against mumps to over 88%.
An early second dose is a good idea though if your child might be exposed to mumps in an ongoing outbreak, has only had one dose of MMR, and is age-eligible for the second dose (over age 12 months and at least 28 days since the first dose). Your child would eventually get this second dose anyway. Unlike the early dose before 12 months, this early dose will count as the second dose of MMR on the immunization schedule.
“Persons previously vaccinated with 2 doses of a mumps virus–containing vaccine who are identified by public health authorities as being part of a group or population at increased risk for acquiring mumps because of an outbreak should receive a third dose of a mumps virus–containing vaccine to improve protection against mumps disease and related complications.”
Recommendation of the Advisory Committee on Immunization Practices for Use of a Third Dose of Mumps Virus–Containing Vaccine in Persons at Increased Risk for Mumps During an Outbreak
This third dose of MMR is not for post-exposure prophylaxis though, which again, doesn’t work for mumps. It is to prevent mumps from ongoing exposures.
You should still watch for signs and symptoms of mumps over the next 12 to 25 days though, as no vaccine is 100% effective. Your vaccinated child won’t need to be quarantined though.
Most importantly, in addition to understanding that vaccines are safe and necessary, know that the ultimate guidance and rules for what happens when a child is exposed to mumps will depend on your local or state health department.
What to Know About Getting Exposed to Mumps
Talk to your pediatrician if your child gets exposed to mumps, even if you think he is up-to-date on his vaccines, as some kids need a third dose of the MMR vaccine during on-going mumps outbreaks.