I took my son to Taipei’s hospital for 18-month well baby check-up yesterday (his first well baby check-up in Taiwan); he had his 5 in 1 (prevnar) shot.

According to Toronto’s immunization schedule, one should be given the Mumps, Measles, and rubella (MMR) shot during both 12 months and 18 months well baby check up. However, I asked the doctor why my son wasn’t given the MMR, he said Taiwan only give MMR once, which, during 15 months.

I’m wondering if the dose of MMR given in Canada the same as Taiwan. If they’re the same, why does Toronto give MMR twice, but Taiwan only give it once.

Please advise. Thanks!!

That’s interesting that he said Taiwan only gives it once. What he might have meant is that it is only given once during the standard baby check-ups. Some places in the world, including HK, give the second dose closer to the beginning of primary school. Note that the second dose is not a booster, like when you get a second tetanus shot years after the first one to boost flagging immunity. The reason most countries give a second dose of the MMR is that up to 5% of the population does not develop immunity to the measles after the first jab, and so need a second one. I don’t know why that is. Maybe the measles part of the vaccine is especially sensitive to slight body temperature changes or whatever. It could just be that the immunologists in Taiwan have found that a high enough percentage of the local population develop immunity after the first jab to insure herd immunity, so they don’t bother with the second dose.