Pakistan’s summers are brutal. In cities like Multan, Sukkur, and Jacobabad, temperatures regularly exceed 45°C — some of the highest ambient temperatures recorded anywhere on earth. For pharmaceutical and veterinary cold chain operations, this isn’t just uncomfortable, it’s a genuine threat to the integrity of temperature-sensitive products.
This article is a practical guide for cold chain managers and procurement teams in Pakistan on how to correctly use ice gel packs during summer to ensure your vaccines and medicines stay within the 2–8°C target range regardless of how hot it gets outside.
Why Summer Changes Everything for Cold Chain
During cooler months, a mediocre cold chain setup may work adequately. An old cold box, a couple of gel packs, and you can probably get through a delivery run without a significant temperature excursion. But come April, that same setup will fail. The thermal load on your cold box increases exponentially as the ambient temperature rises — a box that maintains 6°C at 25°C ambient may only hold 10°C at 40°C ambient with the same number of packs.
This is why summer is when temperature excursion incidents spike across Pakistan’s pharma and veterinary distribution networks. It’s also why suppliers like Plastocraft see their highest demand between April and August.
The Right Number of Packs Per Cold Box
One of the most common mistakes is under-packing a cold box. Here is a practical guideline for common cold box sizes used in Pakistan:
- 3-litre vaccine carrier (EPI-style): 2 × 400g packs, conditioned to 0°C
- 10-litre cold box: 4 × 400g packs for up to 8 hours; 6 packs for up to 14 hours
- 20-litre cold box: 6–8 × 400g packs for up to 12 hours
- Large transport cooler (40+ litres): 10–14 packs depending on load and route duration
These numbers assume packs are fully frozen (at -18°C to -20°C), correctly conditioned before use, and the cold box is kept closed as much as possible during transit.
Conditioning Gel Packs Correctly — The Step Most People Skip
Here’s something that surprises many people: putting packs directly from the freezer into a cold box with vaccines can freeze the vaccines. Frozen vaccines — especially live attenuated vaccines like OPV — are permanently damaged and cannot be used.
The correct procedure, per WHO cold chain guidelines:
- Remove gel packs from the freezer (they will be at approximately -18°C to -20°C).
- Leave them at room temperature for 30–60 minutes.
- Check them periodically. When you hear liquid sloshing inside and the outer surface is wet with condensation but no longer rock solid, they are conditioned.
- Now they are safe to place adjacent to vaccines in the cold box.
This step is non-negotiable for pharmaceutical cold chain. Skipping it is one of the leading causes of vaccine freeze damage in Pakistan’s distribution network.
Choosing the Right Cold Box for Pakistan’s Summer
Not all cold boxes are equal. For summer use in Pakistan, look for:
- Thick polyurethane foam insulation (at least 5cm walls) — cheap EPS foam boxes are not adequate above 38°C
- Tight-fitting lid with a seal — any gap lets warm air in continuously
- Pre-cooling the cold box — before packing, place conditioned gel packs inside for 30 minutes to cool the box walls, then repack with vaccines
Storage at Depots During Power Outages
Pakistan’s power outages (loadshedding) are an additional challenge. A fully packed cold box with quality gel packs can maintain temperature for 12–24 hours without power — but only if the lid stays closed. Train staff to never open the cold box during a power outage unless absolutely necessary. Keep a thermometer inside and log temperatures every 4 hours during extended outages.
Summer Supply Planning — Order Early
Gel pack demand surges in April as temperatures begin rising. By May and June, suppliers are often running on backorder. Place your summer stock order in March or early April to ensure you have enough packs on hand for your peak season needs without paying rush delivery rates.
Plastocraft recommends calculating your monthly gel pack consumption, multiplying by 3, and placing a single bulk order before the season begins. This typically results in cost savings of 15–20% compared to smaller repeat orders, and eliminates the risk of running short during peak season.
To plan your summer order, contact us at +92 321 888 9636 or info@plastocraft.pk.