Soon after the outbreak of COVID-19, we evaluated platforms for COVID-19 vaccine development, including viral vector and mRNA-based technologies. Due to the severity of the pandemic and the urgent need for an effective vaccine against COVID-19, we wanted a technological platform that would enable us to develop a vaccine with a good safety and efficacy profile in a timely manner. We decided to use the adenovirus vector for COVID-19 vaccine development because we have an established technological platform for the adenovirus vector, based on which we have already developed a TB booster, CVE vaccine, Zika vaccine and the recombinant Ebola vaccine, jointly developed with the Beijing Institute of Biotechnology, Academy of Military Medical Sciences, and which was approved in China in 2017. Leveraging the established technological platform of the adenovirus vector and our experienced team, the development of Convidecia made rapid progress. The project was initiated on January 20th, 2020, and entered Phase I trials on March 16th, 2020, making it the first of its kind worldwide to enter clinical study.

Genes related to virus replication are removed from the adenovirus type 5 vector used in Convidecia so that the vector is replication-defective in the human body. A gene sequence encoding the COVID-19 spike protein (S protein) is inserted into that location. The viral vector serves as a carrier that delivers the gene sequence of S protein into cells. Once it has entered a cell, the gene sequence is transcribed to express S protein, which in turn serves as an antigen that stimulates the immune system to recognize the COVID-19 virus.

①Before vaccination, your doctor will make inquiries about your medical history and health conditions to decide if you are eligible to receive the vaccine. Please make honest disclosures. ②After vaccination, all individuals should be observed for 30 minutes to monitor if any adverse reaction occurs. On the day of vaccination, please keep the injection site dry and clean, and we recommend being well rested. ③Within one week after vaccination, please avoid exposure to your known allergens or other common allergens and minimize the use of alcohol and the intake of spicy food. It is recommended to have a light diet and adequate fluid intake.

Please see the label instructions of respective COVID-19 vaccines for detailed contraindications and strictly follow the instructions. In general, individuals with a known history of severe allergic reactions to any component of the vaccine are contraindicated. Additionally, individuals who have fever, an acute disease or a breakout of an underlying chronic disease should postpone the vaccination.。

Before mass vaccination reaches a higher level of immune protection, one should maintain awareness to prevent infection and transmission and should maintain personal hygiene habits. Vaccinated or not, one should still wear a mask indoors and follow specified prevention and control measures.

①The most common adverse reactions after vaccination are fever, redness, swelling and pain in the vaccination site. Usually, a reaction can be relieved by itself within 96 hours, and no special treatment is required. ②If the symptoms are serious or the severity cannot be judged by yourself, one should seek medical treatment immediately and report to the doctor at the vaccination site. ③According to previous experience, serious adverse reactions will occur within 30 minutes after vaccination. Please observe as required and ask for the doctors on site.

Any history of allergies will be considered as a precaution. Individuals with a known history of severe allergic reactions to any component of the vaccine are contraindicated. For individuals with common allergies to pollen with symptoms such as blocked nose, runny nose or rash, it is recommended to avoid getting the COVID-19 vaccine during an ongoing allergic reaction or follow your doctor’s instructions in the case of mild symptoms.