--- title: "Vaccine and medicine cold chain | Nexus Observatory" description: "Vaccines spoil when refrigerators fail, power cuts last too long or doors are left open. Remote temperature monitoring of every fridge…" url: https://observatory.global/industries/humanitarian/cold-chain/ publisher: Nexus Observatory Inc. updated: 2026-11-02 --- [Nexus Observatory](https://observatory.global/) / [Humanitarian](https://observatory.global/industries/humanitarian/) / [Specialized fields](https://observatory.global/industries/humanitarian/fields/) / **Vaccine and medicine cold chain** # Every dose kept cold, every hour on record. Vaccines spoil when refrigerators fail, power cuts last too long or doors are left open. Remote temperature monitoring of every fridge, with power and door state, alerts health workers and technicians in time and gives programmes a record of every dose's temperature history. [Plan a deployment](https://observatory.global/contact/deployment/) How it works [Station Builder](https://observatory.global/studio/builder/) **Industry**: Humanitarian **Measurements**: 4 **Sources cited**: 4 1. Humanitarian · Vaccine and medicine cold chain A fridge between a dose and a child Vaccines spoil when refrigerators fail, power cuts last too long, doors are left open or freeze-sensitive vaccines freeze. In many clinics a failure is found days later. Remote monitoring lets health workers and technicians act in time and gives the programme a temperature history for every fridge. 2. What is measured Temperature, power and doors A logger inside every refrigerator and freezer records temperature every few minutes. Door sensors record openings during busy clinics, and power meters show whether mains, solar or battery is feeding the fridge, so a fault can be told from a power cut. InstrumentsTemperature loggers · Door sensors · Power meters 3. The base node Excursions caught early The node checks every reading against the fridge's safe range, raises heat and freezing alarms with their duration, predicts how long a fridge will hold during a power cut and keeps the full history when links fail, sending it when they return. 4. Radio and links Alarms to the right phone Most clinics have some coverage, so alarms reach the health worker and the district technician by cellular. Clinics beyond coverage send their alarms by satellite. Temperature histories reach the programme's logistics system through the same path, with nothing for health workers to upload. LinksPublic cellular · Satellite 5. How it works From a failing fridge to safe vaccines On a Friday evening a clinic fridge's temperature starts to climb while power is normal. The node raises an alarm; the health worker moves the vaccines to a cold box, and the district technician arrives on Saturday with a replacement part. Every dose's temperature history is recorded. 6. From order to operation · Order Scope the cold chain The scope reads the programme's facilities, refrigerator types, power at each, supply chain levels and the latest vaccine management assessment. Nexus Observatory Inc. returns monitoring per facility, alert routing, technician workflow, training and a price per fridge and per year. [Plan a deployment](https://observatory.global/contact/deployment/) 7. From order to operation · Survey Survey clinics and depots Crews visit representative facilities with programme staff: refrigerator models and power, solar systems, where loggers and door sensors go, who responds to alarms, and coverage for backhaul. Findings set the kit for each facility type. Findings shape the kit for each site before anything is built. 8. From order to operation · Permits Programme approvals The immunisation programme approves the monitoring devices against its prequalification policy, agrees who receives alarms at each level, and sets data sharing with partners. Every approval is kept with the facility record. No crew goes to site before its approvals are in place. 9. From order to operation · Build Build and configure Loggers are checked against a reference thermometer, nodes are configured with each fridge's safe range and the alarm routing, enrolled with their identities and tested with door sensors and power meters before they ship to the district stores. Nothing ships until the whole kit has passed its tests together. [Open the Station Builder](https://observatory.global/studio/builder/) 10. From order to operation · Install Install with health workers Crews and district technicians fit loggers in each refrigerator, door sensors and power meters, mount the node and backhaul, and train health workers to read the display and acknowledge alarms. Every fridge is photographed and recorded. Crews follow the site safety plan throughout the work. 11. From order to operation · Commission Commission with a test alarm Each node proves its identity. Logger readings are compared with a reference thermometer, a controlled door opening and power cut test the alarms, and alerts are acknowledged by the health worker and the district technician before the facility enters service. 12. From order to operation · Operate Respond to every excursion District logisticians see every fridge in the district, its temperature, power and alarms. Technicians are sent to failing fridges first, vaccines are moved before they spoil, and every excursion and response is recorded for the programme. Every alert and action is kept on the record. 13. From order to operation · Maintain Repair and review Technicians repair fridges from alarm history and power data, loggers are checked against references on the agreed plan, software updates arrive remotely, and excursion records feed the programme's next vaccine management assessment. Every change is kept with the facility record. [Book field services](https://observatory.global/contact/field-service/) 14. Data products For health workers and logisticians Health workers and district technicians receive excursion alarms; district and national logisticians receive cold chain dashboards; programme managers and partners receive equipment performance records; vaccine management assessors receive the temperature history of every facility, each tied to the fridge and the time. [See the data products](https://observatory.global/data-products/) 15. Evidence Prequalified, and assessed Refrigerators and temperature monitoring devices follow the international performance specifications for immunisation equipment, off-grid power follows the rural electrification specifications, and records support the effective vaccine management assessment. Every reading, excursion and response is signed and kept with its facility, ready for the assessors. Drawn againstWHO PQS E003 · WHO PQS E006 · IEC TS 62257 · Effective Vaccine Management (EVM) 2.0 16. What you get Sensing as a Service Observation networks designed, installed, operated and maintained for a monthly fee: weather, hydromet, air, seismic and environmental stations, with data delivered under a licence. Delivered as managed service and data licence, for agencies, utilities, municipalities, insurers, agribusiness. Scale: Global, multi-site, per-site pricing. [Talk to sales](https://observatory.global/contact/sales-enquiry/) 17. Next step Plan vaccine and medicine cold chain with us Tell us the site, the measurements and the rules it answers to. We reply with a survey proposal, a design and a scope for vaccine and medicine cold chain. An engineer replies with a survey proposal and a scope, and the plan grows from one site to the network you need, at your pace. [Plan a deployment](https://observatory.global/contact/deployment/) [Open the Station Builder](https://observatory.global/studio/builder/) [Open the Studio](https://observatory.global/studio/) **01** The place and its hazards ## Where it runs, and what can go wrong. Operating contextImmunisation programmes use refrigerators and temperature monitoring devices prequalified against international performance specifications, and the effective vaccine management initiative assesses every level of the supply chain. Many clinics run solar direct-drive refrigerators off grid, and failures are often found days later. Hazards - Refrigerator failures found days later - Power cuts that outlast a fridge's hold-over - Freezing that destroys freeze-sensitive vaccines - Doors left open during busy clinics - Technicians far away with no warning of failure **02** What must be measured ## What, where, how often, and under which rules. Each measurement names where it is taken, how often, and the public standard or regulation behind it. Numbers in the sources column open the cited source below. | Measurement | Where | Cadence | Sources | | --- | --- | --- | --- | | Refrigerator temperature | Inside every vaccine refrigerator and freezer | Every few minutes | 12 | | Power and solar supply | Mains, solar and battery supply to each fridge | Continuous | 32 | | Door openings | Each refrigerator door | On event | 1 | | Temperature excursions and responses | Every excursion from alarm to action | Every event | 4 | **03** The observation stack ## From one base unit to a network. The same blocks at every scale: instruments and a base node, a site with its radio, a fleet run as one, and a network federated on the open protocol. 1. **01** Base unit A fridge point: a remote temperature logger and door sensor with a power meter on a small node. [Build a station →](https://observatory.global/studio/builder/) 2. **02** Site A facility: every refrigerator at a clinic or depot on one node with cellular or satellite backhaul. [Plan a site →](https://observatory.global/contact/deployment/) 3. **03** Fleet Every facility of a district or country watched as one cold chain, with one view for logisticians and technicians. [Managed offers →](https://observatory.global/industries/humanitarian/solutions/) 4. **04** Network Programmes and partners share cold chain records and equipment performance through open standards. [The open protocol →](https://observatory.global/protocol/) - **01** Energy and power-quality meter - **02** Micro node (Nano) - **03** Cellular modem/router - **04** LEO flat-panel terminal - **05** Solar array Radio and links ### Public cellular Most clinics have some coverage; alerts go to health workers' phones by cellular. Radio and links ### Satellite Clinics beyond coverage send alarms by satellite. Edge computeThe node checks every reading against the safe range, alerts on heat and freezing excursions with their duration, predicts hold-over during power cuts and keeps the full temperature history even when links fail. PowerLoggers carry their own batteries; the node runs from the clinic's solar or mains supply with a battery that outlasts long cuts. **04** How it works ## From the instrument to the product. One observation's path, tier by tier, with the interface on every link and a bill of materials below; then how the one node grows to a site, a fleet and federated networks. Vaccine and medicine cold chain: data path – of 06 01 Instruments Measurement with sensor identity andcalibration 02 Node – Wrap in an observation envelope with timequality– Measure quality and uncertainty, attachquality flags– Buffer locally (store-and-forward when thelink drops) 03 Backhaul Commit with transactional outbox andpublish, delivered at least once 04 Site Consumer inbox deduplicates and applieseach record once into governed data 05 Data store Governed product through API, map orexport, correction-aware 06 Products MQTTOGC SensorThings APIGS1 07 Power and structure Supplies 12 V DC, 48 V DC to the fieldequipment Remote temperature loggers and doorsensors in refrigerators Not in the reference kit 01 Energy and power-quality meter SDI-12 · RS-485 · Ethernet 02 Micro node (Nano) Ethernet · USB · Analogue I/O ·RS-485 · CAN 03 Cellular modem/router Ethernet · USB · RS-232 04 LEO flat-panel terminal Ethernet Site MQTT 5 with Sparkplug B Governed data store Versioned, correction-aware Excursion alarms Cold chain dashboards Equipment performance records Temperature history by facility 05 Solar array RS-485 USB RS-485 · Modbus Ethernet Ethernet LTE/NR Satellite IP From the instrument to the published product: each band is a tier, each connector names its interface, and the numbers match the bill of materials. Hover or focus a block to trace its path; scroll or step to follow one observation. | Item | Equipment | Data ports | Protocols | Power in | | --- | --- | --- | --- | --- | | 01 | **Energy and power-quality meter** Meter for voltage, current, power, energy and power quality at a site or on a feeder. | SDI-12RS-485Ethernet | Modbus, IEC 61850 (MMS, GOOSE), DNP3 (IEEE 1815), MQTT 5 | 12 V DC | | 02 | **Micro node (Nano)** Single-board or module-class node for sensor sites, gateways and low-power deployments. | EthernetUSBAnalogue I/ORS-485CAN | MQTT 5, OMA LwM2M, CoAP | PoE, 12 V DC, USB PD | | 03 | **Cellular modem/router** LTE or NR modem or router that uses a public carrier or private network as backhaul. | EthernetUSBRS-232 | 3GPP E-UTRA air interface, 3GPP NR air interface, OMA LwM2M | 12 V DC, PoE | | 04 | **LEO flat-panel terminal** Electronically steered flat-panel user terminal for low-Earth-orbit broadband constellations. | Ethernet | — | PoE, 48 V DC, AC mains | | 05 | **Solar array** PV modules with charge controller sized to the site's load and climate. | RS-485 | Modbus | — | How it scales 01 Instruments Arbitrary qualified sensors and instruments whosemeasurements are ingested with calibration, units,geometry, time, custody and uncertainty. ×n 02 Node The minimum useful deployable unit: server, ruggedappliance, radio node, sensor gateway, satelliteterminal, AI, scientific, vehicle or virtual node. Node Node agent 03 Site The minimum independently operable localgovernance and failure domain: one or more nodesplus local network, identity, policy, evidence,storage, products and operator surfaces. SITE Node Node Node ×n 04 Cluster An optional scale or specialisation domain forscheduling, shared storage, accelerators or datalocality. CLUSTER ×n 05 Fleet Coordinates plans, acknowledgements,convergence evidence, update campaigns andcorrection propagation across nodes and sites. FLEET Fleet controller ×n 06 Federation An exchange of products, capabilities, events orwork across approved, independently administeredtrust domains, using explicit trust, policy,data-locality, version and correction contracts. TRUST DOMAIN TRUST DOMAIN TRUST DOMAIN ×n Verifier Applications Data in the field Telemetry Control Data upstream Control Data upstream Control Exchange Evidence Events Exchange The smallest deployable unit is one node; the same unit is replicated to meet the demand. Nodes form a site, sites may form a cluster, sites and clusters are coordinated as a fleet, and fleets exchange across independently administered trust domains. Each plane is a separate channel with its own open binding. **Data in the field**: MQTT 5 with Sparkplug B; connectors for LoRaWAN, OPC UA and instrument buses. **Telemetry**: OpenTelemetry OTLP. **Control**: TLS 1.3 with mutual authentication; protobuf messages over gRPC or HTTP/2. **Data upstream**: At-least-once publication with repeat-safe keys over the control channel or NATS JetStream; QUIC MAY be used on lossy links. **Evidence**: DSSE-signed in-toto statements; SLSA provenance; SCITT transparency receipts. **Events**: Event envelopes mapped to CloudEvents 1.0; channels described in AsyncAPI 3. **Exchange**: OpenAPI 3.1; the OGC API family; SensorThings; STAC; WIS 2.0. **05** From order to operation ## Every step, from the first call to a running site. The same crew and the same record carry the work from scope to maintenance. 1. 01 Order Scope the cold chain The scope reads the programme's facilities, refrigerator types, power at each, supply chain levels and the latest vaccine management assessment. Nexus Observatory Inc. returns monitoring per facility, alert routing, technician workflow, training and a price per fridge and per year. 4 2. 02 Survey Survey clinics and depots Crews visit representative facilities with programme staff: refrigerator models and power, solar systems, where loggers and door sensors go, who responds to alarms, and coverage for backhaul. Findings set the kit for each facility type. Findings shape the kit for each site before anything is built. 3. 03 Permits Programme approvals The immunisation programme approves the monitoring devices against its prequalification policy, agrees who receives alarms at each level, and sets data sharing with partners. Every approval is kept with the facility record. No crew goes to site before its approvals are in place. 1 4. 04 Build Build and configure Loggers are checked against a reference thermometer, nodes are configured with each fridge's safe range and the alarm routing, enrolled with their identities and tested with door sensors and power meters before they ship to the district stores. Nothing ships until the whole kit has passed its tests together. 1 5. 05 Install Install with health workers Crews and district technicians fit loggers in each refrigerator, door sensors and power meters, mount the node and backhaul, and train health workers to read the display and acknowledge alarms. Every fridge is photographed and recorded. Crews follow the site safety plan throughout the work. 6. 06 Commission Commission with a test alarm Each node proves its identity. Logger readings are compared with a reference thermometer, a controlled door opening and power cut test the alarms, and alerts are acknowledged by the health worker and the district technician before the facility enters service. 1 7. 07 Operate Respond to every excursion District logisticians see every fridge in the district, its temperature, power and alarms. Technicians are sent to failing fridges first, vaccines are moved before they spoil, and every excursion and response is recorded for the programme. Every alert and action is kept on the record. 4 8. 08 Maintain Repair and review Technicians repair fridges from alarm history and power data, loggers are checked against references on the agreed plan, software updates arrive remotely, and excursion records feed the programme's next vaccine management assessment. Every change is kept with the facility record. 4 **06** Data products and integration ## What it delivers, to whom, and into which systems. Data products - **Excursion alarms** Health workers and district technicians - **Cold chain dashboards** District and national logisticians - **Equipment performance records** Programme managers and partners - **Temperature history by facility** Vaccine management assessors Integration - **Logistics information system** Temperature and alarm records reach the programme's logistics system. - **Maintenance** Failing fridges open repair tasks for technicians. - **Partners** Equipment performance is shared with partners who supply refrigerators. Exchanged through MQTT, OGC SensorThings API, GS1. **07** Questions buyers ask ## Before you scope it. Does it replace prequalified loggers? It uses devices that meet the programme's prequalification policy. What about solar fridges? Solar supply is monitored with the fridge. Who gets the alarm? Routing is set by the programme, usually the health worker and the district technician. Does it work without coverage? Satellite carries alarms from clinics beyond coverage. **08** Resources ## The sources behind this page. Public standards, regulations and guidance, cited where they apply. Each applies only where its jurisdiction or scope does. 1. **1** [WHO PQS E006: Temperature monitoring devices](https://www.who.int/) World Health Organization 2. **2** [WHO PQS E003: Refrigerators and freezers for storing vaccines](https://www.who.int/) World Health Organization 3. **3** [IEC TS 62257: Renewable energy and hybrid systems for rural electrification](https://webstore.iec.ch/) International Electrotechnical Commission 4. **4** [Effective Vaccine Management (EVM) 2.0](https://www.who.int/) World Health Organization and UNICEF **09** Related ## Use cases and solutions. [Solution Sensing as a ServiceObservation networks designed, installed, operated and maintained for a monthly fee: weather, hydromet, air, seismic and environmental stations, with data delivered under a licence.Solutions for humanitarian →](https://observatory.global/industries/humanitarian/solutions/#sensing-service) [Solution Microgrids and off-grid site powerPV, storage and generator sizing for instruments and edge sites, with telemetry and remote control.Solutions for humanitarian →](https://observatory.global/industries/humanitarian/solutions/#site-power) [Solution Field services across the site lifecycleSurvey, design, installation, commissioning, maintenance, refurbishment and decommissioning with every part recorded.Solutions for humanitarian →](https://observatory.global/industries/humanitarian/solutions/#field-lifecycle) **10** Humanitarian: specialized fields ## Other fields of this industry. [Specialized field Displacement sites and campsWeather, heat, flood, water supply and storage at camps and displacement sites, so site managers protect people from the hazards of the place and keep water flowing.The full field →](https://observatory.global/industries/humanitarian/displacement-sites/) [Specialized field Field connectivity for respondersSatellite and cellular connectivity, Wi-Fi and mesh for field offices, warehouses and responders, deployed in days, secured and run for the length of the operation.The full field →](https://observatory.global/industries/humanitarian/field-connectivity/) [Specialized field Drought and food security monitoringRain, soil moisture and water point stations where food insecurity follows drought, feeding the indicators that trigger early action before harvests fail.The full field →](https://observatory.global/industries/humanitarian/drought-food-security/) ### Bring us the site. 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