Vaccine MKT Calculator (2–8 °C)

Most refrigerated vaccines are labelled for 2–8 °C storage, so 8 °C is the upper limit checked here (the lower limit — freezing — is a separate, often more serious, concern). The authoritative limit is whatever your product's labelled storage condition and stability data specify — read it off the marketing authorisation, the manufacturer's storage statement or the governing pharmacopoeia, and enter your real temperature history against it.

No — and this is critical. MKT addresses heat-driven degradation; it cannot represent freeze damage, which destroys many vaccines (adjuvanted, several mRNA and others) irreversibly even from a brief sub-zero excursion. Always assess the minimum temperature separately: any freezing of a freeze-sensitive vaccine is typically an immediate reject regardless of a passing MKT. Use this calculator for the heat side of the 2–8 °C window, and a freeze-indicator or minimum-temperature check for the cold side.

Because degradation is not linear with temperature — it accelerates roughly exponentially (Arrhenius). A simple average treats an hour at 30 °C the same as an hour at 20 °C either side of 25 °C, but the product is harmed far more by the hot hour. MKT weights each reading by exp(−ΔH/RT), so it reflects the true cumulative chemical stress. It is always ≥ the arithmetic mean, and it is the figure regulators expect for storage and distribution compliance.

Use a representative series with durations — typically the logger's interval readings, or summarised blocks of 'X hours at Y °C' if you only have an excursion summary. The more granular the data, the more accurate the MKT, but the result is dominated by the warm excursions, so capturing those accurately matters most. Don't average data before entering it — that defeats the point; enter the temperatures and let the calculator do the kinetic weighting.