https://orcid.org/0000-0001-8880-0392
We wish to thank Dr. Finsterer’s comments on our article published in Human Vaccine & Immunotherapeutics.Citation1 In our article, the overall incidence of any self-reported adverse events (AEs) after the first and second dose of COVID-19 vaccine composed of inactivated SARS-CoV-2 among Chinese healthcare workers (HCWs) was 38.2% (532/1392) and 31.0% (325/1047) respectively, and none of the vaccinated HCWs reported severe AEs and required hospitalization.Citation2 Dr. Finsterer concerned that, in contrast to the reported severe AEs after administration of COVID-19 mRNA vaccines (Biontech Pfizer or Moderna vaccine) or adenovirus vector vaccines (Astra Zeneca or Johnson and Johnson Vaccine), no severe AE was observed in Chinese HCWs vaccinated with China-made inactivated COVID-19 vaccines. Thus, Dr. Finsterer proposed that China-made vaccines may have a lower risk of AEs or that severe side effects were not published due to political, economical, or personal reasons.Citation1
As AEs presented in our article were self-reported through filling in the questionnaires by HCWs,Citation2 Dr. Finsterer considered that HCWs who had severe AEs after vaccination were unable to participate in the investigation, leading to missing the severe AEs.Citation1 Indeed, we could not absolutely exclude such a possibility. However, other doubts, such as filling in the questionnaire by a third person or unwillingness to consent severe AEs,Citation1 are unlikely. We clearly stated at the beginning of the questionnaire that “The questionnaire is anonymous. Whether or not answering the questionnaire is all determined based on your own willingness, and will not influence any of your interests and will not cause any negative effect to you. If you are willing to participate in this survey, please complete the questionnaire independently and objectively.”Citation2 Based on the survey contents,Citation2 the identity of participants cannot be identified, and anonymity of the participants is guaranteed. Thus, if the participants did not want to participate in the survey, they could decline, and they had no incentive to have a third party to fill out the questionnaire.
Dr. Finsterer concerned that HCWs working in public institutions may hold back the severe AEs that they had truly experienced because of fear of getting into troubles with the employer.Citation1 However, such a thing is less likely to occur nowadays in China. In fact, several Chinese scholars reported several severe AEs after vaccination with China-made inactivated COVID-19 vaccines.Citation3,Citation4 Moreover, we are independent investigators, not employers; the participants enrolled in our study had no reason or motivation to hold back severe AEs if they had really experienced.
The phase 3 clinical trials of inactivated COVID-19 vaccines (Aikewei [Sinopharm] and/or CoronaVac [Sinovac], Beijing, China) were not conducted in China because of the ‘zero’ infection of SARS-CoV-2 after the first wave of the pandemic, but conducted in other countries, among tens of thousands of people in the United Arab Emirates and Bahrain,Citation5 Turkey,Citation6 Indonesia,Citation7 or among more than 4 millions of persons in Chile,Citation8 however, severe AEs were rarely reported. The real-world data in other countries, such as Turkey, Iran, and Algeria, show that the incidence of any AEs and severe AEs in people vaccinated with China-made inactivated COVID-19 vaccines is much lower than that in those who were vaccinated with mRNA or adenoviral-backbone COVID-19 vaccines.Citation9–11 As of 15 June 2022, in addition to the use of over 3.39 billion doses in mainland China, more than 2.2 billion doses of China made inactivated COVID-19 vaccines were rolled out in more than 120 countries or regions. However, severe AEs after vaccination of these inactivated COVID-19 vaccines were very rarely reported. A case-control study conducted in Hong Kong, where inactivated vaccine CoronaVac (Sinovac) and mRNA vaccine BNT162b2 (Pfizer-BioNTech) were both approved, showed an elevated risk for carditis after the use of BNT162b2 but not after the use of CoronaVac, by comparing the incidence of carditis between 3.29 million persons who received either CoronaVac (2 291 444 doses) or BNT162b2 (3 496 629 doses) and those who did not receive COVID-19 vaccine.Citation12 In addition, an inactivated COVID-19 vaccine prepared in India also showed highly safe in tens of thousands of persons, without severe AEs.Citation13
In summary, the self-reported AEs after COVID-19 vaccination in Chinese HCWs in our articleCitation2reflected the real situations. Together with the results reported by investigators in China and other countries, COVID-19 vaccines composed of inactivated SARS-CoV-2 have relatively low incidence of severe AEs, compared to mRNA or adenovirus-based COVID-19 vaccines.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Funding
References
- Finsterer J. Side effects of SARS-CoV-2 vaccines should be assessed by unbiased professionals on-site. Hum Vaccin Immunother. 2022;in press. doi:10.1080/21645515.2022.2090178.
- Cheng Y, Li T, Zheng Y, Xu B, Bi Y, Hu Y, Zhou YH. Self-Reported adverse events among Chinese healthcare workers immunized with COVID-19 vaccines composed of inactivated SARS-CoV-2. Hum Vaccin Immunother. 2022;18(5). doi:10.1080/21645515.2022.2064134.
- Yu BY, Cen LS, Chen T, Yang TH. Bell’s palsy after inactivated COVID-19 vaccination in a patient with history of recurrent Bell’s palsy: a case report. World J Clin Cases. 2021;9(27):1–2. doi:10.12998/wjcc.v9.i27.8274.
- Chen X, Li X, Li H, Li M, Gong S. Ocular adverse events after inactivated COVID-19 vaccination in Xiamen. Vaccines (Basel). 2022;10(3):482. doi:10.3390/vaccines10030482.
- Al Kaabi N, Zhang Y, Xia S, Yang Y, Al Qahtani MM, Abdulrazzaq N, Al Nusair M, Hassany M, Jawad JS, Abdalla J, et al. Effect of 2 inactivated SARS-CoV-2 vaccines on symptomatic COVID-19 infection in adults: a randomized clinical trial. Jama. 2021;326(1):35–45. doi:10.1001/jama.2021.8565.
- Tanriover MD, Doganay HL, Akova M, Güner HR, Azap A, Akhan S, Köse Ş, Erdinç FŞ, Akalın EH, Tabak ÖF, et al. Efficacy and safety of an inactivated whole-virion SARS-CoV-2 vaccine (CoronaVac): interim results of a double-blind, randomised, placebo-controlled, phase 3 trial in Turkey. Lancet. 2021;398(10296):213–222. doi:10.1016/S0140-6736(21)01429-X.
- Fadlyana E, Rusmil K, Tarigan R, Rahmadi AR, Prodjosoewojo S, Sofiatin Y, Khrisna CV, Sari RM, Setyaningsih L, Surachman F, et al. A phase III, observer-blind, randomized, placebo-controlled study of the efficacy, safety, and immunogenicity of SARS-CoV-2 inactivated vaccine in healthy adults aged 18-59 years: an interim analysis in Indonesia. Vaccine. 2021;39(44):6520–6528. doi:10.1016/j.vaccine.2021.09.052.
- Jara A, Undurraga EA, González C, Paredes F, Fontecilla T, Jara G, Pizarro A, Acevedo J, Leo K, Leon F, et al. Effectiveness of an inactivated SARS-CoV-2 vaccine in Chile. N Engl J Med. 2021;385(10):875–884. doi:10.1056/NEJMoa2107715.
- Babaee E, Amirkafi A, Tehrani-Banihashemi A, SoleimanvandiAzar N, Eshrati B, Rampisheh Z, Asadi-Aliabadi M, Nojomi M. Adverse effects following COVID-19 vaccination in Iran. BMC Infect Dis. 2022;22(1):476. doi:10.1186/s12879-022-07411-5.
- Baydar O, Özen Ş, Öztürk Şahin B, Köktürk N, Kitapçı MT. Safety of an inactivated SARS-CoV-2 vaccine among healthcare workers in Turkey: an online survey. Balkan Med J. 2022;39(3):193–198. doi:10.4274/balkanmedj.galenos.2022.2021-11-25.
- Lounis M, Rais MA, Bencherit D, Aouissi HA, Oudjedi A, Klugarová J, Pokorná A, Klugar M, Riad A. Side effects of COVID-19 inactivated virus vs. adenoviral vector vaccines: experience of Algerian healthcare workers. Front Public Health. 2022;10:896343. doi:10.3389/fpubh.2022.896343.
- Lai FTT, Li X, Peng K, Huang L, Ip P, Tong X, Chui CSL, Wan EYF, Wong CKH, Chan EWY, et al. Carditis after COVID-19 vaccination with a messenger RNA vaccine and an inactivated virus vaccine: a case-control study. Ann Intern Med. 2022;175(3):362–370. doi:10.7326/M21-3700.
- Ella R, Reddy S, Blackwelder W, Potdar V, Yadav P, Sarangi V, Aileni VK, Kanungo S, Rai S, Reddy P, et al. Efficacy, safety, and lot-to-lot immunogenicity of an inactivated SARS-CoV-2 vaccine (BBV152): interim results of a randomised, double-blind, controlled, phase 3 trial. Lancet. 2021;398(10317):2173–2184. doi:10.1016/S0140-6736(21)02000-6.