Vaccines 2023, 11, 93. https://doi.org/10.3390/vaccines11010093 www.mdpi.com/journal/vaccines Case Report Impact of Improper Storage of ChAdOx1-S (AstraZeneca) Vaccine on Its Efficacy and Safety Marek Mikołajczyk ¹, Roman A. Lewandowski ² and Anatoliy G. Goncharuk 3, * 1 Allergology Department of the Voivodeship Rehabilitation Hospital for Children in Ameryka, 11-015 Olsztynek, Poland 2 Institute of Management and Quality Science, Faculty of Economics, University of Warmia and Mazury in Olsztyn, 10-720 Olsztyn, Poland 3 Hauge School of Management, NLA University College, 4633 Kristiansand, Norway * Correspondence: anagon@nla.no Abstract: Background: In May 2021, there was an incident regarding giving patients AstraZeneca vaccines stored improperly. They were stored at room temperature (21 degrees centigrade) for 18 h, 12 h longer than the producer recommends. Aim of the study: The paper aims to contribute to the body of knowledge concerning the efficacy and safety of the ChAdOx1-S (AstraZeneca) vaccine concerning the requirements for cold supply chain specification. Patients and methods: Improperly stored vaccines were given to 44 patients, and 39 of them decided to take part in the study. The Control group consisted of 56 people vaccinated on the same days by the same medical teams, using properly stored medicines. Results: The concentration of anti-S1 SARS-CoV-2 Spike protein IgG an- tibodies did not differ significantly between the groups. Examined group median 70 kU/L (20;100). Control group median 66 kU/L (32.75;100), p = 0.751. We did not observe any COVID-19 infections in either the control or examined group for half a year after the incident. People from each group reported that local and systemic adverse events occurred directly after the first and second doses. In the control group, one case of spontaneously subsiding face edema and joint pain was observed. There were no severe or fatal adverse events. There were no significant differences between the groups, besides the fatigue, after the second dose. Conclusion: AstraZeneca vaccine ChAdOx1-S stored at 21 degrees centigrade for 18 h before vaccination has the same safety profile (p < 0.05) and the same efficacy (p < 0.05) as the vaccines stored in conditions recommended by the producer. Keywords: ChAdOx1-S (AstraZeneca) vaccine; COVID-19 vaccination; cold supply chain; vaccine efficacy; vaccine safety 1. Introduction At the end of 2019, the COVID-19 pandemic broke out first in China and gradually spread all over the world. The plague spread quickly, leading to a large number of hospi- talizations and deaths. There were no known ways of treating this new disease, and many countries lapsed into prolonged lockdowns. Humanity was then confronted for a long time with an unseen medical hazard. The scientific community started a frantic race to recognize the infection factor named SARS-CoV-2 and to find an effective treatment. Sci- entists acted on vaccine development. There were many attempts to create a working preparation. The first working products were based on the mRNA coding virus Spike protein closed in a lipid capsule. The Moderna and Biontech-Pfizer vaccine brought prom- ising results in clinical trials and were introduced for common COVID-19 prevention in the developed world [1,2]. Scientists trying to use harmless viruses as vectors to transmit information about virus proteins into human cells also noted successes. Oxford University and AstraZeneca used the chimpanzee airway virus to activate the human immune sys- tem against the SARS-CoV-2 Spike protein with good effect [3]. Johnson&Johnson Citation: Mikołajczyk, M.; Lewandowski, R.A.; Goncharuk, A.G. Impact of Improper Storage of ChAdOx1-S (AstraZeneca) Vaccine on Its Efficacy and Safety. Vaccines 2023, 11, 93. https://doi.org/10.3390/ vaccines11010093 Academic Editor: Pedro Plans-Rubió Received: 4 November 2022 Revised: 25 November 2022 Accepted: 28 December 2022 Published: 30 December 2022 Copyright: © 2022 by the au- thors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and condi- tions of the Creative Com- mons Attribution (CC BY) li- cense (https://creativecom- mons.org/licenses/by/4.0/).