Cold-Chain Storage for the DRC Response: Keeping Vaccines Viable to the Last Mile

To keep vaccines usable in the Democratic Republic of the Congo, every storage point from the airport to the health post must hold a steady +2 °C to +8 °C, with no freezing. That is the WHO PQS standard, and it is the whole job. The challenge in the DRC is not the standard; it is meeting it at a clinic that has no mains electricity, after a multi-day road and river move, with a refrigerator that has to ride out a power cut without breaching.

What temperature must vaccines be held at, and to what standard?

Vaccines must be stored between +2 °C and +8 °C with no freezing, and the equipment that does it should be prequalified under the WHO Performance, Quality and Safety (PQS) scheme. WHO PQS E003 refrigerators and freezers are tested and listed against exactly this requirement, which is why "PQS-prequalified" is the specification to write into a tender, not a generic "vaccine fridge".

That single band, +2 °C to +8 °C, governs every link of a humanitarian cold-chain store. A breach above the band degrades the vaccine; freezing below it can destroy it outright for freeze-sensitive products. For a response across the DRC, where consignments move far from any reliable grid, the equipment has to hold that band on its own, which is where the choice of refrigerator stops being a formality.

How do you keep vaccines cold where there is no reliable electricity?

You specify equipment built for an unreliable grid: ice-lined refrigerators (ILRs) and solar direct-drive (SDD) units, both available as PQS-prequalified models. A WHO PQS ice-lined refrigerator holds vaccines below +8 °C on as little as eight hours of mains electricity per 24 hours, and stays cold for at least 20 hours during a power cut. That holdover is the property that matters in the field, because it turns an intermittent or failing grid into a survivable one.

The need is not marginal. Globally, around one billion people are served by health facilities with no access to electricity, which is the precise gap that solar and ice-lined cold chain is built to close. Gavi's Cold Chain Equipment Optimisation Platform (CCEOP) has procured more than 62,500 grid and solar fridges and installed over 46,000 across Gavi-supported countries as of June 2021, backed by more than US$160 million, evidence that off-grid PQS equipment is the established answer at scale, not an experiment. SLS specifies and supplies this class of equipment for UN and NGO programmes and lands it ready to run.

ILR or solar direct-drive: which refrigerator for the DRC?

Choose by the power situation at the site, not by habit. Where a site has some mains or generator power, even a few intermittent hours a day, a PQS ice-lined refrigerator is the pragmatic choice, because it holds below +8 °C on eight hours of electricity and rides out a cut for 20 hours or more. Where a site has no usable grid at all, solar direct-drive removes the fuel and grid dependency entirely.

On cost, the case for solar is stronger than it first looks. WHO PQS estimates the 10-year life-cycle cost of solar direct-drive vaccine refrigerators as equal to or lower than gas-powered systems, so the recurring spend on gas, fuel logistics, and resupply is what makes SDD competitive over the life of the equipment, not just its environmental profile. Our view for a deep-field DRC site with no grid is to default to PQS solar direct-drive and reserve ILRs for sites with at least intermittent power; SLS sizes and supplies both classes through one chain so the decision is made on the site survey, not on what a vendor happens to stock.

What changed with the PQS data-logger mandate in January 2026?

From January 2026, the WHO PQS specification for E003 refrigerators tightened to require an integrated electronic temperature-monitoring (data-logger) capability, so a compliant unit now records its own temperature history rather than relying on a separate device. Practically, that means any cold-chain equipment you procure for the DRC response should be checked against the current PQS E003 listing, because a unit that met the old spec may no longer be the one to buy.

This matters most at implementation. A logger that travels inside the unit gives you an auditable temperature record from the central store all the way to the health post, which is exactly the evidence a programme needs to prove the cold chain held, or to find where it broke. SLS specifies to the current standard and configures monitoring before equipment ships, so the record starts the moment the vaccine goes in, not the moment someone remembers to switch a logger on.

How do you keep the cold chain intact to the last mile?

Treat the cold chain as one unbroken sequence of controlled-temperature points, not a fridge at each end with a gap in between. The breaches happen in the transitions: the time on the apron, the road and river legs, the transfer at a forward store, the final run to the health post. Each of those needs a plan, passive cold boxes and packed ice for the moving legs, PQS storage at every fixed point, and equipment chosen so a power cut at any node does not become a breach.

That is the chain SLS owns end to end. We specify PQS-compliant cold storage and refrigeration, clear it through customs, hold it at our in-region facilities, and run the last mile across the DRC and the wider region, then keep the equipment maintained through the response. A vendor that sells you only the refrigerator has handed you every transition in between, which is precisely where viable vaccines are lost.

Why preposition cold-chain capacity rather than buy it during an outbreak?

Because the equipment that protects a vaccine response cannot be sourced at the speed an outbreak demands. PQS-prequalified refrigerators, the spares, and the passive cold boxes have lead times, and an outbreak in the DRC does not wait for a procurement cycle to close. Cold-chain capacity standing in-region before a response is the difference between vaccinating on the outbreak's timeline and vaccinating on a supplier's.

The regional demand behind that is real and growing: the Middle East and Africa cold chain market was valued at USD 13.10 billion in 2025 and is projected to reach USD 23.72 billion by 2034, a compound annual growth rate of 6.82%. That trajectory tells a procurement team two things: the equipment ecosystem is deepening, and demand for it is rising fast enough that lead times will be contested. SLS holds and sources PQS-compliant cold-chain equipment in-region and supplies it through one design-to-deployment chain, so a DRC response is not waiting on a freight booking when the first cases are confirmed.

Frequently asked questions

What temperature range must vaccines be stored at?

Between +2 °C and +8 °C with no freezing, the band that WHO PQS E003 refrigerators are tested and prequalified to maintain.

How long can a PQS ice-lined refrigerator hold temperature during a power cut?

A WHO PQS ice-lined refrigerator holds vaccines below +8 °C on as little as eight hours of electricity per 24 hours and stays cool for at least 20 hours during a power cut.

Is solar direct-drive more expensive than gas-powered cold chain?

No; WHO PQS estimates the 10-year life-cycle cost of solar direct-drive vaccine refrigerators as equal to or lower than gas-powered systems, once fuel and resupply are counted.

Why is off-grid cold-chain equipment necessary in places like the DRC?

Because around one billion people are served by health facilities with no access to electricity, so solar and ice-lined refrigerators are needed to hold the cold chain where there is no reliable grid.

What changed in the WHO PQS refrigerator specification in January 2026?

From January 2026 the PQS E003 specification requires integrated electronic temperature monitoring, so buyers should check equipment against the current PQS E003 listing before procuring.

Specify the cold chain, not just the fridge

SLS is Hallgruppen's authorised regional distributor, and we deliver cold-chain design, deployment, last-mile movement, and customs as a single chain rather than four separate purchases. We are in-country across five countries, including the DRC, with our own crews and customs expertise, and we are a UNGM-registered vendor (380716), so we can transact with UN buyers directly. If you are standing up a vaccine response and need the cold chain to hold from the apron to the health post, request a quotation from SLS and we will specify to the current PQS standard, deploy it, and keep it running.