Table 3.

Applications of digital technologies in COVID-19 vaccination.

Field of COVID-19 vaccination	Algorithm	Blockchain	Mobile health	Internet of Things (IoT)	Others
Strategy of COVID-19 vaccination	XGBoost model [133,134] Genetic algorithms [135,136] Fuzzy logic system [137] Random forest [134] Logistic regression [134] Long short-term memory [138] Autoregressive Integrated Moving Average Model [138] Reinforcement learning [139] Disease propagation graph [140] Spatial artificial intelligence [141]	N/Aa	N/A	N/A	N/A
Distribution and delivery of COVID-19 vaccines	No specifics [142,143] Spatiogeographical model, minimum-cost flow problem, and self-designed scheduling algorithm [144] Double Deep Q-Network, Advantage Actor Critic, Trust Region Policy Optimization, Actor-Critic using Kronecker-Factored Trust Region, and Linear Upper Confidence Bounds model [145] Long short-term memory [146,147] Gray Wolf Optimization [148] Variable neighborhood search [148,149] Whale Optimization Algorithm [149] Artificial neural network and convolutional neural network [150] Heuristic algorithm [151] Machine learning [152] Unsupervised self-organizing map, recurrent neural network, and Stochastic Mixture Density Network [147]	No specifics [142,152-154] Ethereum [155,156] Smart contract [156-161]	N/A	No specifics [142,143,162] Software-Defined Networking-IoT model [163]	5G-UAVCN [157] 6G-eRLLC [161]
Model prediction of COVID-19 vaccination	Logistic regression [164] Linear regression [165,166] AdaBoost [164,167] Boost classification [166] Decision tree [164,165] Random forest [164,166,167] Long short-term memory [168,169] DeepAR [169] Support vector machine [165] Autoregressive model [166] Extra trees [167] Gradient boosting [167] XGBoost [167]	N/A	N/A	N/A	N/A
COVID-19 vaccination services	AnyLogic model and a trained neural network [170] Accelerated Dual Ascent [171] Decreasing order-based algorithm, iterative random algorithm, and clustering algorithm [172] K-means clustering [173]	N/A	App [174-177] Personalized message/email [178]	N/A	Online tool [179] Cloud storage [180] Digital twin [177]
Certification of COVID-19 vaccination	Yolov5 deep learning model [181] Dense convolutional networks [182] Convolutional neural networks [183]	Ethereum [184-186] Smart contract [184,187-189] Hash algorithm [190] Blockchain adaptor (Canis Major) [191]	Mobile phone app [186] A digital Yellow Card on mobile phone [192]	N/A	Biometrics [181,193]
Postvaccination surveillance	N/A	Smart contract [194]	Mobile app (Respon) [195] Mobile app (vaxEffect@UniMiB) [196]	N/A	N/A

^aN/A: not applicable.