POST 00448E : USE OF VVMs ON ALL VACCINES
Follow-up on Post 00446E
4 May 2002
_________________________________________________
Some more comments and questions about the use of VVMs were received. First
from G R Baru, Project Officer (Cold Chain) at the UNICEF/India country
office (mailto:[log in to unmask])
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My comments on Dr Jayaprakash’s observation on VVM of OPV is that beside
high ambient temperature, sustained exposure to vaccine even at lower
temperature is a major a factor to bring change in VVM status. I took one
vial of OPV-VVM stage-2 from one of the PHCs in Bihar (India) which reached
stage-3 within 3 hours at ambient temperature whereas an OPV vial which I
took from another PHC at the same stage-2 changed its color to stage-3
after 8 hours.
This appears that the latter one had more cumulative effect of higher
temperature. During my recent visit to Iraq for strengthening of cold chain
maintenance, I also observed that VVM changes color from stage-2 to 3 even
during storage in kerosene oil refrigerators. It could be due to the reason
that kerosene refrigerators normally do not maintain 2-8°C temperature when
ambient temperature is above 45°C thereby exposing vaccines at higher
temperature for a sustained duration.
We do not have any experience with VVMs on measles vaccine as it is yet to
be introduced in India.
_________________________________________________
Bal Ram Bhui from the CORE Group PEI, Nepal
(mailto:[log in to unmask]) also contributes the following.
_________________________________________________
While the people in immunization business are excited and eager to see all
vaccine with VVMs, the concerned manufacturers also need to look at the
integrity of labels on the vaccine vials. Our experience with OPV VVMs
suggest that the label can come off the vials. The melting of ice on the
icepack and frost produced inside the cold box made vials sufficiently wet
to allow labels to come off even with normal handling of vials. I think
this should be a serious issue for researchers, manufacturers and health
workers when we want to use VVM as a management tool.
__________________________________________________
Ãœmit Kartoglu from WHO (mailto:[log in to unmask]) shares these comments and
answers to questions raised above.
__________________________________________________
The observation by Dr. Jayaprakash is quite interesting and shows how the
informed choice could be taken. This also underlines the important fact
that VVM is the ONLY tool that is available at all times during
distribution and storage as well as when the vaccine is administered,
indicating whether the vaccine has been exposed to a combination of
excessive heat over time and whether it is likely to have been damaged.
However, we should also keep in mind that such experiments may produce
confusing results. VVM reaction rate is not only affected by heat exposure,
but also by UV light. When a vial is taken out for such an experiment, the
reaction rate will depend on the combined affect of the ambient temperature
and the UV light exposure. This is why all VVM validation tests (and the
tests conducted by LifeLines for lot release of each batch) are conducted
in temperature-controlled water baths with NO lights.
The problem of vaccine labels coming off as indicated by Bal Ram Bhui from
Nepal is not directly linked with VVM. UNICEF and GAVI tenders require
"water-resistant" adhesive for the vaccine labels. This is listed among the
"minimum requirements" for vaccines to be procured by UNICEF: QUOTE
"Vaccine vial labels shall be affixed with water-resistant adhesive so that
the labels do not become loose or fall off." END QUOTE
Regarding complaints, we [WHO] need to know the vaccine manufacturer and
the type of presentation in question. For such complaints, we encourage
colleagues to contact directly Dr. Nora Dellepiane
(mailto:[log in to unmask] ) at WHO-HQ in Geneva.
One way of preventing vials getting wet is to use ziplock bags. This can be
used especially with vaccines intended to be used in subsequent sessions
within the multi-dose vial policy (MDVP). Vials submerged in water cannot
and should not be used in subsequent sessions. Using ziplock bags can also
help in facilitating this condition for MDVP implementation. Ziplock bags
are available from UNICEF Supply Division: S0521425, Envelope, plastic,
10x15cm, pkt of 100, $0.41 PER PKT OF 100. Even if they are cheap,
volume-wise they are quite small and cannot accommodate many vials. Maybe
UNICEF SD could purchase bigger sizes if required.
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