The development of COVID-19 vaccine is highly concerned by all countries in the world. So far, many kinds of COVID-19 vaccines have entered phase III clinical trial. However, it is difficult to deliver COVID-19 vaccines efficiently and safely to the areas affected by the epidemic. This paper focuses on vaccine transportation in a supply chain model composed of one distributor and one retailer (clinic or hospital), in which the distributor procures COVID-19 vaccines from the manufacturer and then resells them to the retailer. Distributor detects the activity level of the vaccines, and retailer is responsible for transportation of the vaccines. Firstly, we establish a difference equations model with time-delay. Secondly, we investigate the impact of time-delay on the stability of vaccine supply chain. In addition, we explore the influence of decision adjustment speed of the distributor (or retailer) on the stability of vaccine supply chain. Finally, we verify the theoretical results by a two-dimensional bifurcation diagram, the largest Lyapunov exponent, entropy, and domain of attraction. The results show that when the decision delay-time or the adjustment speed of decision variables exceeds a certain threshold, it brings a negative impact on the stability of vaccine supply chain system. The stability domain of the system shrinks as customers’ sensitivity to cold chain transportation decreases and by contrast expends as customers’ sensitivity to vaccine prices decreases. When the vaccine supply chain is in a state of chaos, the effect of external control over the system is superior to that of internal control over the system.

COVID-19疫苗的开发受到世界所有国家的高度关注。到目前为止，许多种COVID-19疫苗已进入III期临床试验。但是，很难有效，安全地将COVID-19疫苗运送到受疫情影响的地区。本文主要关注由一个分销商和一个零售商（诊所或医院）组成的供应链模型中的疫苗运输，其中分销商从制造商那里购买COVID-19疫苗，然后再将其转售给零售商。分销商会检测疫苗的活性水平，而零售商负责疫苗的运输。首先，建立具有时滞的差分方程模型。其次，我们研究了时间延​​迟对疫苗供应链稳定性的影响。此外，我们探讨了分销商（或零售商）的决策调整速度对疫苗供应链稳定性的影响。最后，我们通过二维分叉图，最大的李雅普诺夫指数，熵和吸引域来验证理论结果。结果表明，当决策延迟时间或决策变量的调整速度超过一定阈值时，会对疫苗供应链系统的稳定性产生负面影响。随着客户对冷链运输的敏感性降低，系统的稳定性范围缩小，相反，随着客户对疫苗价格的敏感性降低，系统的稳定性范围也随之扩大。当疫苗供应链处于混乱状态时，对系统进行外部控制的效果要优于对系统进行内部控制的效果。