Health logistics: medicines, cold chain and quality assurance

1The basic rules for health products

Health products (medicines, medical devices, laboratory reagents, vaccines) are subject to stricter rules than other items, because a mistake can kill:

• Reference lists: the national essential medicines list, the WHO model list, national treatment protocols. A medicine not authorised in the country is not imported without a waiver.
• Qualified suppliers: WHO prequalification for certain products, recognised humanitarian procurement centres, manufacturers that comply with good manufacturing practices. Purchases on the uncontrolled local market are the exception, with reinforced controls.
• Standard kits: for example the Interagency Emergency Health Kits (IEHK), designed for 10,000 people for 3 months, useful at the start of a crisis but to be replaced afterwards by orders adapted to actual consumption.
• Batch traceability: every receipt and issue records the batch number and the expiry date, so that a batch can be withdrawn in the event of a recall.

2Quantifying health needs

Two main methods:

• Consumption method: based on the AMC corrected for stock-outs (see week 2). Reliable if the data are good and prescribing is rational.
• Morbidity method: number of expected cases × standard treatment. Useful at start-up or when consumption data are distorted.

Morbidity example. Population 50,000; malaria incidence during the season: 8% per month; 60% of cases seek care; 70% of cases are adults. Adult treatment: 24 tablets; child (according to weight, average used): 12 tablets. Cases treated per month: 50,000 × 8% × 60% = 2,400. Tablets: 2,400 × (0.7 × 24 + 0.3 × 12) = 2,400 × (16.8 + 3.6) = 2,400 × 20.4 = 48,960 tablets per month. Over a 4-month season, plus a 2-month safety stock: 6 × 48,960 = 293,760 tablets.

The two methods cross-check each other: a large difference signals a problem (irrational prescribing, leakage, under-use of services).

3The cold chain

Vaccines and many biological products must be kept between +2 °C and +8 °C; some must be frozen. A break can render them ineffective with no visible sign.

Equipment: cold rooms, prequalified refrigerators and freezers (WHO PQS catalogue), solar direct-drive refrigerators, cold boxes and vaccine carriers with conditioned ice packs, temperature loggers.

Sizing. Net storage volume = number of doses × volume per dose (cm³) × period factor (maximum stock). Example: measles campaign, 60,000 children, expected wastage rate 15%, 10-dose vials. Doses required = 60,000 / 0.85 ≈ 70,590, rounded to 70,600, i.e. 7,060 vials. Volume per packed dose: 2.6 cm³ (to be checked on the product sheet). Volume: 70,600 × 2.6 ≈ 183,600 cm³ ≈ 184 litres net, to which the diluent is added (often stored at room temperature but refrigerated before use).

Monitoring. Temperature reading twice a day, electronic loggers with alarms, vaccine vial monitors (indicators that change colour after cumulative exposure to heat). Any temperature excursion is documented and assessed according to the manufacturer's instructions before the product is used.

4Wastage rate and vaccine efficiency

The vaccine wastage rate combines opened vials not fully used, expired products and cold chain breaks.

Wastage factor = 1 / (1 − wastage rate). With a wastage rate of 20%, the factor is 1.25: to vaccinate 1,000 children, 1,250 doses are needed.

Example. 1,000 vials of 10 doses distributed; 6,400 children vaccinated. Doses used: 10,000; wastage rate = (10,000 − 6,400) / 10,000 = 36%. For a 10-dose multi-dose vial in sessions with few children, part of this wastage is unavoidable; the multi-dose vial policy (keeping certain opened vials for up to 28 days under conditions) and the organisation of sessions reduce it. The rate must be compared with the national programme's target.

5Falsified products, recalls and waste

Falsified or substandard products. They circulate widely in countries with weak regulatory capacity. Signs: different packaging, spelling mistakes, abnormally low prices, inconsistent batch numbers. Course of action: quarantine, report to the national authority and to the WHO Global Surveillance and Monitoring System, no distribution.

Batch recalls. Thanks to traceability, it is possible to identify within a few hours where the units of the batch concerned are: warehouses, health centres, patients if necessary.

Controlled substances. Narcotics and psychotropics (morphine, for example) require specific import authorisations, double-lock storage and a special register.

Waste. Expired medicines, sharps waste, infectious waste: segregation at source, safety boxes, appropriate incineration or an approved disposal channel, destruction report. Burning medicines in the open air is dangerous and often illegal.

6Quality assurance and good distribution practices

Good distribution practices cover the entire journey of a health product:

• a clean, dry, ventilated warehouse, with temperature and humidity readings (often below 25 °C for ordinary medicines, according to the labelling);
• strict FEFO, quarantine and rejected product zones;
• transport that protects against heat, humidity and theft;
• trained staff, with a pharmacist or qualified person who validates receipts;
• written procedures and self-inspections.

Performance indicators of a health supply chain: availability of tracer products (for example 15 essential medicines monitored in each centre), stock-out days, expiry rate, inventory discrepancies, replenishment time for health centres.

Tracer product availability = number of tracer products in stock on the day of the visit / number of tracer products monitored. A centre at 9 out of 15 (60%) cannot provide proper care.