Assessment of temperatures in the vaccine cold chain in two provinces in Lao People’s Democratic Republic: a cross-sectional pilot study
Kitamura et al. BMC Res Notes
Assessment of temperatures in the vaccine cold chain in two provinces in Lao People's Democratic Republic: a cross-sectional pilot study
Tomomi Kitamura 0 3
Viraneth Bouakhasith 2 3
Kongxay Phounphenghack 2 3
Chansay Pathammavong 2 3
Anonh Xeuatvongsa 2 3
Masataro Norizuki 0 3
Hironori Okabayashi 0 3
Yoshio Mori 1 3
Munehito Machida 3 4
Masahiko Hachiya 0 3
0 Bureau of International Cooperation, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku , Tokyo 1628655 , Japan
1 Laboratory of Rubella, Department of Virology III, National Institute of Infectious Diseases , Murayama Branch, 4-7-1
2 National Immunization Program, Ministry of Health , Lao PDR, Simuang Road, Vientiane , Lao People's Democratic Republic
3 Gakuen , Musashimurayama, Tokyo 208-0011 , Japan
4 Department of Global Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University , 13-1 Takaramachi , Kanazawa , Ishikawa 9208640 , Japan
Objective: All childhood vaccines, except the oral polio vaccine, should be kept at 2-8 °C, since the vaccine potency can be damaged by heat or freezing temperature. A temperature monitoring study conducted in 2008-2009 reported challenges in cold chain management from the provincial level downwards. The present cross-sectional pilot study aimed to assess the current status of the cold chain in two provinces (Saravan and Xayabouly) of Lao People's Democratic Republic between March-April 2016. Two types of temperature data loggers recorded the temperatures and the proportions of time exposed to < 0 or > 8 °C were calculated. Results: The temperature remained within the appropriate range in the central and provincial storages. However, the vaccines were frequently exposed to > 8 °C in Saravan and < 0 °C in Xayabouly in the district storage. Vaccines were exposed to > 8 °C during the transportation in Saravan and to both > 8 and < 0 °C in Xayabouly. Thus, challenges in managing the cold chain in the district storage and during transportation remain, despite improvements at the provincial storage. A detailed up-to-date nationwide analysis of the current situation of the cold chain is warranted to identify the most appropriate intervention to tackle the remaining challenges.
Vaccines; Cold chain; Storage; Transportation; Temperature
Immunization is one of the most important
achievements in public health, and a major contributor for this
success is the expanded program on immunization (EPI)
]. The EPI was initiated in Lao People’s Democratic
Republic (Lao PDR) in 1979, and the immunization
coverage has been improving since then; however, the
country has experienced outbreaks of vaccine-preventable
diseases lately, and one of the reasons was speculated as
several steps of the cold chain potentially being
The World Health Organization and vaccine labels
state that all childhood vaccines, except for oral polio
vaccines, should be kept at 2–8 °C to ensure their quality,
efficacy, and safety, since most vaccines are sensitive to
heat or freezing temperatures [
]. In Lao PDR,
the supply chain consists of three levels. The vaccines are
dispatched from the National Immunization Program
(NIP) storage in the capital to the regional or provincial
storage. Subsequently, they are sent to the district
storage. Finally, they reach the health centers.
Immunization services are provided either at the health facilities or
during outreach sessions in the villages. A temperature
monitoring study conducted in 2008–2009 by the United
Nations Children’s Fund (UNICEF) reported several
challenges in cold chain management from the provincial
level downward and the vaccines were exposed both
overheating and freezing [
]. A new strategy has been
implemented such as continuous monitoring at
storage since then. With this in mind, the present study and
aimed to assess the current status of the cold chain, at all
levels, in two representative provinces of Lao PDR.
This was a cross-sectional pilot study conducted from
March to April 2016. Two provinces, one each in the
northern and southern part of Lao PDR, were
deliberately selected by the NIP since these two provinces are
good representatives of all 18 provinces considering their
population and geographical characteristics (Fig. 1). One
district per province and five health centers per district
were selected by the EPI officers of the NIP and the
Provincial Health Department from each province. Sampling
method is a purposive sampling and sample size was
justified since this study tested feasibility and
acceptability of the study protocol for a larger study in the future.
The ambient temperature was not recorded in this study
to avoid the complexity of the procedure for the health
care workers. DTP-HepB-Hib vaccines was agreed to
transport through a normal vaccine transportation route
among the researchers before the study was conducted.
Two types of temperature data loggers were used and
randomly assigned to the final destination: MicroLite™
(Sato Shouji Inc., Japan) and CUSTOM™ (CUSTOM,
Japan). MicroLite™ was pre-set to record
temperatures every two minutes and CUSTOM™ was set to
record every 5 min. The health care workers were all
pre-informed about the study, however they were not
informed about the monitoring intervals and the
loggers were pre-set to avoid manipulations by the health
care workers to minimize the bias. The recordings were
started on 17/3/2016 and lasted until 11/4/2016. All data
loggers and vaccines started to travel down to the
provinces on 24/3/2016. A monitoring form was developed
and attached with the vaccines and temperature data
loggers to record the dates of events such as the arrival
and departure of the vaccines. The provincial/district
EPI officers and the health center staff recorded the
information in the forms. The temperature data loggers
and monitoring forms were packed with the vaccines in
the vaccine carriers and transported using the normal
transportation route. Once they reached the provincial/
district storage, they were stored in the refrigerator with
the vaccines until they were ready to be dispatched to the
All data were downloaded from each temperature
data logger as an Excel spreadsheet or PDF file. The
analysis conducted in the study was descriptive and the
proportions of time exposed to < 0 and > 8 °C were
calculated. The precise times (hours or minutes) of arrival
and departure were not recorded, and the duration of
transportation was defined from 0:00 on the departure
date to 23:59 on the arrival date. The duration of
storage was defined as 24 h per date not indicated as being in
No ethical clearance or informed consent was
necessary, since there was no intervention or interaction with
]. However, authorization to conduct this
study was granted by the Ministry of Health and the
Provincial Health Departments [
Eight and six days of recordings were analyzed for the
loggers that went to Saravan (23/3/2016–31/3/2016) and
Xayabouly (23/3/2016–29/3/2016), respectively.
Saravan, ranged from 21 to 37 °C, while the recorded
temperatures in Saravan ranged between 0.2 and 18.0 °C;
these were below the ambient temperature recorded
in Pakse. The temperature in Luang Prabang, which is
located 49 km from Xayabouly, ranged from 18 to 35 °C.
In Xayabouly, the temperature ranged between − 3.3 and
20.4 °C [
Proportions of exposure to suboptimal temperature
throughout the observation period
On average, the vaccines were exposed to > 8 °C for 41%
of the total recorded time in Saravan (37–45%). They
were not exposed to < 0 °C. The corresponding
proportions in Xayabouly were 5% (5–6%) and 15% (11–19%),
Ambient temperature and range of temperature during the study period
Ambient temperature was not recorded in this study. The
temperature ranged from 19 to 38 °C in Vientiane,
capital of Lao PDR, during the study period. The temperature
in Pakse and Champasak, which are located 54 km from
Proportions of exposure to suboptimal temperature
No exposure to suboptimal temperature in the central
storage was observed 1 day prior to the vaccines and data
loggers being dispatched (Table 1). The times spent at the
provincial and district storages were 2 days in Saravan
and 1 day in Xayabouly. No exposure to suboptimal
temperature was seen in the provincial storage in both
provinces. In Saravan, the loggers recorded more than 80%
of the time spent in the storage as being at above 8 °C
(range of proportion: 84–100%, range of temperature:
7.9–11.9 °C), whereas there was no exposure to < 0 °C at
the district storage. In Xayabouly, no exposure to > 8 °C
was recorded; however, more than 50% of the time, the
temperature was recorded as < 0 °C (range of proportion:
44–68%, range of temperature: − 2.7 to 6.3 °C) at the
Proportions of exposure to suboptimal temperature
The times required to transport the vaccines from the
capital to the province, from the province to the
district, and from the district to the health centers were 2,
1 and 1 day, respectively, in both provinces (Table 2).
The vaccines were exposed to >8 °C at an average of
48% (45–50%), 51% (41–61%), and 32% (27–39%) of
the time spent for transportation from the capital to
province, from province to district, and from district to
health center, respectively in Saravan. They were never
exposed to < 0 °C. The differences in maximum and
minimum temperature were 11.0, 11.4 and 17.8 °C
respectively (capital → province: maximum 15.5 °C, minimum
4.5 °C; province → district: max 16.8 °C, min 5.4 °C;
district → health center: max 18.0 °C, min 0.2 °C). The
vaccines were exposed to > 8 °C at an average of 6% (5–10%),
18% (13–25%), and 8% (2–11%) of the time during
transportation in Xayabouly and to < 0 °C at an average of 0%,
12% (9–17%), and 32% (8–51%) of the time during
transportation from the capital to province, from province to
district, and from district to health center, respectively.
The ranges of temperature were 16.8, 15.8 and 23.7 °C,
respectively (capital → province: max 18.4 °C, min 1.6 °C;
province → district: max 14.3 °C, min –2.7 °C;
district → health center: max 20.4 °C, min − 3.3 °C).
This pilot study aimed to identify the current temperature
control of vaccines in Lao PDR. This study discovered
challenges during the storage at the district and during
transportation, and these challenges differed according to
the region. The vaccines were exposed to both
overheating and freezing.
The study of temperature monitoring in 2008–2009
by UNICEF pointed out significant weaknesses of cold
chains in terms of material and human resources from
the provincial level downwards, including improperly
maintained or outdated refrigeration equipment, poor
compliance with cold-chain procedures, inadequate
monitoring, and poor understanding of the dangers of
freezing vaccines [
]. The present study showed that the
temperature remained within the appropriate range in
the provincial level storage. However, at the district
storage, the vaccines were still exposed to either overheating
or freezing during a high proportion of the time spent
there. The temperature exceeded 5 °C above or below the
appropriate temperature range. Besides the weaknesses
pointed out by UNICEF, the studies from five different
countries described an unstable power supply or lack of
contingency plans during power cuts a lack of training
on the cold chain, insufficient supervision to implement
proper monitoring, lack of access to guidelines or
Standard Operating Procedures, and improper management
of the budget for the cold chain might be root causes of
inappropriate cold chain management below the district
10, 11, 13, 14, 19, 20, 22
In the present study, the vaccines were exposed to
either overheating or freezing throughout the
transportation from the central to the health centres as well,
however the differences in the maximum and minimum
temperature was greater than 10 °C, suggesting that the
temperature control during transport was more unstable
than that in storage. In addition to the reasons mentioned
above, the studies from four different countries described
the characteristic reasons during transport as unstable
temperature control during transportation might be due
to improper management of ice packs, unexpected delays
in transportation due to road or vehicle conditions, and
improper means of transporting vaccine [
10, 11, 13, 19,
]. The study by Nanthavong et al. mentioned the
possibility of cold chain breaks during transport in Lao PDR
Emphasis has long been placed on avoiding high
temperatures, but, as this study also showed, recent
studies have reported exposure to freezing temperature at
many stages during distribution [
12, 23, 24
]. The World
Health Organization guidelines specify that the
hepatitis B, diphtheria–tetanus–pertussis, diphtheria–tetanus,
and tetanus toxoid vaccine must not be frozen [
avoid freezing of vaccines, Kolwaite et al. conducted a
pilot study to assess the effect of “out-of-the-cold-chain”
storage in Lao PDR and discovered improved Hepatitis
B dose coverage without an increase in adverse reactions
]. Some innovative solutions should be considered in
the context of developing countries, such as a
computerizing temperature monitoring system, development of
thermostable vaccines, development of a compact
prefilled vaccination device, or the use of a cold box that can
manage temperature control on its own for a long
10, 14, 24, 26
This study identified the current status of cold chain
management for vaccines in two provinces in Lao PDR.
Despite improvements in the cold chain management at
the provincial storage, it remains a challenge to manage
the cold chain in the district storage and during
transportation. Both overheating and freezing of vaccines
were identified, and these findings differed according to
the region. A detailed up-to-date analysis of the current
situation of the cold chain at all levels is warranted in
Lao PDR, such as a nationwide cold chain assessment to
implement proper context-specific interventions for
different cold chain management issues.
This study has several limitations. First, this study only
covered two out of 18 provinces. Second, the ambient
temperature was not recorded; however, we speculate
that the temperature loggers were travelled or stored in
the vaccine carriers or refrigerator as instructed, since the
available temperatures from the neighboring provinces
were higher than those recorded in the loggers. Third, the
temperature management in the health center storages
and during the outreach activities were not monitored.
Fourth, the precise times of arrival and departure were
not recorded and the transportation period may thus also
include time spent in the storage. Finally, all health care
workers were conscious that the temperature was being
monitored, thus, their vaccine handling may have been
changed. The results should be carefully interpreted by
considering these limitations.
EPI: expanded program on immunization; Lao PDR: Lao People’s Democratic
Republic; NIP: National Immunization Program; UNICEF: United Nations
TK, VB, KP, CP, and AX carried out data collection in the field. TK, MN, HO, YM,
MM, and MH conducted the data analysis and produced the first draft of the
manuscript. TK edited the final version of the manuscript and was a major
contributor in writing the manuscript. All authors read and approved the final
We acknowledge all the health care workers who took parts in this study and
we respect their hard work in the field despite of the challenging situation.
We also would like to thank Dr. Hiromi Obara and experts from development
partners including JICA, UNICEF, and WHO for offering insightful comments.
The authors declare that they have no competing interests.
Availability of data and materials
The datasets generated and/or analyzed during the current study are available
from the corresponding author on reasonable request.
Consent for publication
Ethics approval and consent to participate
No ethical clearance or informed consent was necessary, since there was no
intervention or interaction with humans. However, authorization to conduct
this study was granted by the Ministry of Health and the Provincial Health
This work was supported by The Grant of National Center for Global Health
and Medicine (27-4, 28-1) and Research Program on Emerging and
Reemerging Infectious Diseases from Japan Agency for Medical Research and
Development (AMED). The funding source had no control over the study.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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