# Situation: A nurse runs the weekly immunization session of a Barangay Health Station (BHS) under the National Immunization Program (NIP) and reviews the station's target client list. An infant who received every dose due at birth and at 6, 10, and 14 weeks comes for the 9-month visit and is well. Under the NIP schedule, which vaccines are due at this visit?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=627151  
> language: ko  
> subject: Nursing Practice I — Community Health Nursing

## 문제

Situation: A nurse runs the weekly immunization session of a Barangay Health Station (BHS) under the National Immunization Program (NIP) and reviews the station's target client list.

An infant who received every dose due at birth and at 6, 10, and 14 weeks comes for the 9-month visit and is well. Under the NIP schedule, which vaccines are due at this visit?

## 보기

1. MMR 1 and bOPV 4
2. MR 1 and IPV 2
3. MMR 1 only
4. MMR 1 and IPV 2 **✔ 정답**

**정답: 4**

## 해설

The NIP gives inactivated polio vaccine (IPV) twice, at 14 weeks and at 9 months, and the first dose of measles-mumps-rubella (MMR) vaccine at 9 months, with the second at 12 months. A fully vaccinated infant therefore receives MMR 1 and IPV 2 at the 9-month visit. Measles-rubella (MR) is the vaccine given in school in Grades 1 and 7 and in catch-up campaigns, and bivalent oral polio vaccine (bOPV) has only three routine doses.

## 심화 해설

Core schedule logic at the 9-month visit

The National Immunization Program (NIP) schedules two doses of inactivated polio vaccine (IPV): the first at 14 weeks and the second at 9 months. The same 9-month visit is also when the first dose of measles-mumps-rubella (MMR) vaccine is given, with the second MMR dose following at 12 months. An infant who completed all doses due at birth and at 6, 10, and 14 weeks has already received the primary series, so the vaccines now due are MMR 1 and IPV 2.

The 9-month visit is a scheduled catch-up point for polio protection because IPV is deliberately given twice in the routine infant schedule, not as a single dose. The first IPV dose at 14 weeks accompanies the end of the primary oral polio series, while the second dose at 9 months reinforces immunity as the infant approaches an age when measles-containing vaccines are also introduced. This pairing of IPV 2 with MMR 1 is a practical feature of the NIP schedule: both vaccines can be safely co-administered at the same visit without compromising immunogenicity.

Key point! MMR is a measles-containing vaccine given at 9 months and 12 months in the routine infant schedule. Measles-rubella (MR) vaccine is a different product used for school-based immunization in Grades 1 and 7 and in catch-up campaigns, not for the routine 9-month infant visit.

Watch out! Bivalent oral polio vaccine (bOPV) has only three routine doses in the NIP schedule. A fourth bOPV dose is not given at 9 months; the polio vaccine due at that age is IPV, which is injectable rather than oral.

Why the schedule pairs IPV with MMR at 9 months

The timing reflects two independent immunological goals that converge at the same age. Measles-containing vaccines are typically deferred until 9 months because maternal measles antibodies, transferred across the placenta, can neutralize the vaccine virus if given too early. By 9 months, those maternal antibody levels have declined enough to allow a reliable immune response to the first MMR dose. The second dose at 12 months is not a booster in the traditional sense; it is given to seroconvert the small percentage of infants who did not respond to the first dose, a strategy that increases population-level measles immunity.

IPV is given at 9 months for a different reason. The oral polio vaccine series, including bOPV, provides strong intestinal mucosal immunity but carries a rare risk of vaccine-associated paralytic poliomyelitis. Adding IPV doses at 14 weeks and 9 months strengthens systemic humoral immunity against all three poliovirus serotypes while reducing reliance on oral vaccine alone. The NIP uses a mixed schedule of bOPV and IPV to balance mucosal protection with the safety and seroconversion reliability of the inactivated vaccine.

Distinguishing the vaccine options

| Vaccine | Routine infant schedule | Key distinction |
| --- | --- | --- |
| MMR | Dose 1 at 9 months, dose 2 at 12 months | Contains measles, mumps, and rubella antigens |
| MR | Not routine for infants | School-based (Grades 1 and 7) and catch-up campaigns only |
| IPV | Dose 1 at 14 weeks, dose 2 at 9 months | Inactivated, injectable polio vaccine |
| bOPV | 3 routine doses (birth, 6 weeks, 10 weeks, 14 weeks depending on schedule) | Oral, bivalent (types 1 and 3); no 9-month dose |

A fully vaccinated infant who completed all earlier doses arrives at the 9-month visit needing MMR 1 and IPV 2, not MMR alone and not MR or bOPV. The presence of IPV 2 as a distinct scheduled dose is the detail that separates the correct answer from the option listing MMR 1 only.

Key point! When a question describes an infant who is up to date on all previous doses and presents at 9 months, the expected vaccines are those scheduled for that exact age. Do not add vaccines from the 12-month visit or from school-based programs.

## 임상 시나리오

9-Month NIP Visit: Vaccine PairingMMR 1 and IPV 2 are co-administered
At the 9-month visit, the NIP schedule requires MMR 1 and IPV 2. The infant has already completed the primary series at birth, 6, 10, and 14 weeks.

IPV is given twice in the routine schedule: first at 14 weeks, second at 9 months. MMR is given at 9 months and 12 months.

CautionDo not confuse MR with MMR. MR is for school-based immunization (Grades 1 and 7) and catch-up campaigns, not the routine 9-month visit. bOPV has only three routine doses; no fourth dose is given at 9 months.

## 핵심 개념

- **MMR** — Measles-mumps-rubella vaccine; first dose at 9 months, second at 12 months.
- **IPV** — Inactivated polio vaccine; given twice in the NIP schedule at 14 weeks and 9 months.
- **bOPV** — Bivalent oral polio vaccine; only three routine doses in the NIP schedule.
- **MR** — Measles-rubella vaccine; used in school-based immunization (Grades 1 and 7) and catch-up campaigns.
- **NIP** — National Immunization Program; the routine immunization schedule for infants and children.

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