From the CDC that we know downplays information they don’t want to deal with
Most children who get MMRV vaccine do not have any problems with it.
Mild Problems
Fever (about 1 child out of 5).
Mild rash (about 1 child out of 20).
Swelling of glands in the cheeks or neck (rare).
If these problems happen, it is usually within 5-12 days after the first dose. They happen less often after the second dose.
Moderate Problems
Seizure caused by fever (about 1 child in 1,250 who get MMRV), usually 5-12 days after the first dose. They happen less often when MMR and varicella vaccines are given at the same visit as separate shots (about 1 child in 2,500 who get these two vaccines), and rarely after a 2nd dose of MMRV.
Temporary low platelet count, which can cause a bleeding disorder (about 1 child out of 40,000).
Severe Problems (Very Rare)
Several severe problems have been reported following MMR vaccine, and might also happen after MMRV. These include severe allergic reactions (fewer than 4 per million), and problems such as:
Deafness.
Long-term seizures, coma, lowered consciousness.
Permanent brain damage.
Because these problems occur so rarely, we can’t be sure whether they are caused by the vaccine or not. (but we wouldn’t put the warning here if we were reasonbly sure there were issues)
From the package insert from Merck.com
Other
Death from various, and in some cases unknown, causes has been reported rarely following
vaccination with measles, mumps, and rubella vaccines; however, a causal relationship has not been
established in healthy individuals (see CONTRAINDICATIONS). No deaths or permanent sequelae were
reported in a published post-marketing surveillance study in Finland involving 1.5 million children and
adults who were vaccinated with M-M-R II during 1982 to 1993.{60}
Under the National Childhood Vaccine Injury Act of 1986, health-care providers and manufacturers
are required to record and report certain suspected adverse events occurring within specific time periods
after vaccination. However, the U.S. Department of Health and Human Services (DHHS) has established
a Vaccine Adverse Event Reporting System (VAERS) which will accept all reports of suspected
events.{49} A VAERS report form as well as information regarding reporting requirements can be
obtained by calling VAERS 1-800-822-7967.