MONOVALENT TYPE 1 ORAL POLIOMYELITIS VACCINE (mOPV1)

Once opened, multi-dose vials should be kept between +2°C and +8°C. Multi-dose vials of mOPV1 from which one or more doses of vaccine have been removed during an immunization session may be used in subsequent immunization sessions for up to a maximum of 4 weeks, provided that all of the following conditions are met (as described in the WHO policy statement: The use of opened multi dose vials in subsequent immunization sessions. WHO/V&B/00.09):

• The expiry date has not passed;
• The vaccines are stored under appropriate cold chain conditions;
• The vaccine vial septum has not been submerged in water;
• Aseptic technique has been used to withdraw all doses;
• The vaccine vial monitor (VVM), if attached, has not reached the discard point (see figure).
  After first opening, immediate use is recommended.

Monovalent Type 1 Oral Poliomyelitis  vaccine (mOPV1)is administered  to stimulate the body mechanism to produce active immunity by simulating the natural infection without producing untoward symptoms of the disease. This is achieved by multiplication of the vaccine virus in the intestinal tract.

In the vast majority of cases there are no side effects reported with the trivalent OPV, that includes the same OPV1 component.  Very rarely,  there may be vaccine-associated paralysis (less than one case per  one million doses administered). Persons in close contact with a  recently vaccinated child may very rarely be at risk of vaccine – associated paralytic poliomyelitis.

No adverse effects are produced by giving mOPV1 to a sick child.

Individuals infected with human immunodeficiency virus (HIV), both asymptomatic and symptomatic, should be immunized with mOPV1 according to standard schedules. However,  the vaccine is contraindicated in those with primary  immune deficiency disease or suppressed immune response from medication, leukaemia, lymphoma or generalized malignancy.

The vaccine comes in a glass vial of 20 doses (2 ml). Due to minor variation of its pH, mOPV1 may vary in colour from light yellow to light red.

Remove the vaccine vial from cold storage and examine the Vaccine Vial Monitor on the label. Vaccine Vial monitors(VVMs) supplied by TEMPTIME Corporation, USA are part of the label on all mOPV1 vials. The colour dot is a time-temperature sensitive dot that provides an indication of the cumulative heat to which the vial has been exposed. It warns the end user when exposure to heat is likely to have degraded the vaccine beyond an acceptable level.The interpretation of the VVM is simple. Focus on the central square. Its colour will change progressively.As long as the colour of this square is lighter than the colour of the ring, then the vaccine can be used. As soon as the colour of the central square is the same colour as the ring or of a darker colour than the ring, then the vial should be discarded. Allow the vaccine to thaw and examine the vial to ensure that the vaccine is clear and transparent. With clean hands,tear off the metal seal, remove the rubber cork and fix the dropper onto the vial. Remove the cap of the dropper and feed two drops of vaccine directly into the mouth of the child by pressing the dropper. Put cap on the dropper and return the vial to cold storage. Once the seal is broken, consume the vaccine as early as possible.

Vaccine, if not handled in an aseptic manner may develop turbidity due to bacterial or fungal contamination. Fingers should never come in contact with the vaccine. The tip of the dropper should never be touched and should always be covered with the  cap while in store. Vaccine should be checked carefully for clarity before every use and must be discarded if found turbid.