Bell's palsy following vaccination with mRNA (BNT162b2) and inactivated (CoronaVac) SARS-CoV-2 vaccines: a case series and nested case-control study

Eric Yuk Fai Wan, PhD, Celine Sze Ling Chui, PhD, Francisco Tsz Tsun Lai, PhD, Esther Wai Yin Chan, PhD, Xue Li, PhD, Vincent Ka Chun Yan, BPharm, Le Gao, MSc,Qiuyan Yu, MPH, Ivan Chun Hang Lam, MPharm, Raccoon Ka Cheong Chun, MClinPharm, Prof Benjamin John Cowling, PhD, Wing Chi Fong, FRCP, Alexander Yuk Lun Lau, MBChB, Prof Vincent Chung Tong Mok, MD, Frank Ling Fung Chan, BScPharm, Cheuk Kwong Lee, MD, Lot Sze Tao Chan, MPH, Dawin Lo, MBChB, Kui Kai Lau, PhD, Prof Ivan Fan Ngai Hung, MD, Prof Gabriel Matthew Leung, MD, Prof Ian Chi Kei Wong, PhD.

Published: August 16, 2021

Findings suggest an overall increased risk of Bell's palsy after CoronaVac vaccination. However, the beneficial and protective effects of the inactivated COVID-19 vaccine far outweigh the risk of this generally self-limiting adverse event. Additional studies are needed in other regions to confirm our findings.

Adverse event reporting and Bell's palsy risk after COVID-19 vaccination - Authors' reply

Ian Chi Kei Wong, Eric Yuk Fai Wan, Celine Sze Ling Chui, Xue Li, Esther Wai Yin Chan

Published: November, 2021


Two-dose COVID-19 vaccination and possible arthritis flare among patients with rheumatoid arthritis in Hong Kong

Xue Li, Xinning Tong, Winnie Wan Yin Yeung, Peng Kuan, Samson Hin Hei Yum, Celine Sze Ling Chui, Francisco Tsz Tsun Lai, Eric Yuk Fai Wan, Carlos King Ho Wong, Esther Wai Yin Chan, Chak Sing Lau, Ian Chi Kei Wong.

Published: October, 2021

Current evidence does not support that full vaccination of mRNA or inactivated virus COVID-19 vaccines is associated with possible arthritis flare.

Inconsistent Safety Outcome Reporting in Randomized Clinical Trials of COVID-19 Vaccines Complicates Informed Medical Decisions

Joseph E. Blais, Yue Wei, Celine S. L. Chui, Esther W. Chan & Ian C. K. Wong.

Published: 17 August, 2021

Comparing self-reported reactogenicity between adolescents and adults following the use of BNT162b2 (Pfizer-BioNTech) messenger RNA COVID-19 vaccine: a prospective cohort study

Results of this study should be informative to parents considering BNT162b2 vaccination for their children in that moderately increased reactogenicity compared with adults is anticipated.

Edward Wai Wa Chan, Miriam Tim Yin Leung, Lauren Ka Wun Lau, Janice Leung, Dawn Lum, Rosa Sze-Man Wong ,Xue Li, Celine Sze Ling Chui, Eric Yuk Fai Wan, Carlos King Ho Wong, Esther Wai Yin Chan, Patrick Ip, Ian Chi Kei Wong, Francisco Tsz Tsun Lai


Published: December 26, 2021


Epidemiology of Acute Myocarditis/Pericarditis in Hong Kong Adolescents Following Comirnaty Vaccination

Gilbert T Chua, FHKCPaed, FHKAM(Paed), Mike Yat Wah Kwan, MSc(Applied Epidemiology) CUHK, Celine S L Chui, PhD, Robert David Smith, PhD, Edmund Chi-Lok Cheung, BSc, Tian Tian, Ma, PhD, Miriam T Y Leung, BPharm, Sabrina Siu Ling Tsao, MBBS(UK), FACC(USA), Elaine Kan, FRCR, FHKCR, Wing Kei Carol Ng, FRCR, FHKAM, Victor Chi Man Chan, MRCPCH, Shuk Mui Tai, MBChB, Tak Ching Yu, MRCPCH, Kwok Piu Lee, FHKAM, FHKCPaed, Joshua Sung Chih Wong, FHKCPaed, FHKAM(Paed), Ying Kit Lin, MRCPCH, Chi Chiu Shek, FHKCPaed, FRCPCH, Agnes Sze Yin Leung, FHKCPaed, FHKAM(Paed), Chit Kwong Chow, FHKCPaed, FHKAM(Paed), Ka Wah Li, FHKCPaed, FHKAM(Paed), Johnny Ma, MMed, Wai Yuk Fung, MBChB, FRCR, Daniel Lee, FRCR, Ming Yen Ng, FSCMR, FACC, Wilfred Hing Sang Wong, PhD, Hing Wai Tsang, PhD, Janette Kwok, PhD, FRCPA, Daniel Leung, PhD (candidate), Kin Lai Chung, MBBS, FRCS, Chun Bong Chow, MD, FRCPCH, Godfrey Chi Fung Chan, MD, FRCPCH(UK), Wing Hang Leung, MBBS(HK), PhD(Johns Hopkins), Kelvin Kai Wang To, MD, FRCPath, Kwok Yung Yuen, MD, FRCPath, Yu Lung Lau, MD(Hon), FRCPCH, Ian Chi Kei Wong, PhD, FRCPCH(Hon), Patrick Ip, MPH, FRCPCH(UK)

Published: 28 November 2021


There is a significant increase in the risk of acute myocarditis/pericarditis following Comirnaty vaccination among Chinese male adolescents, especially after the second dose.

Multimorbidity and adverse events of special interest associated with Covid-19 vaccines in Hong Kong

Francisco Tsz Tsun Lai, Lei Huang, Celine Sze Ling Chui, Eric Yuk Fai Wan, Xue Li, Carlos King Ho Wong, Edward Wai Wa Chan, Tiantian Ma, Dawn Hei Lum, Janice Ching Nam Leung, Hao Luo, Esther Wai Yin Chan & Ian Chi Kei Wong


Published: 20 Jan 2022


No evidence is found that multimorbidity imposes extra risks of adverse events following Covid-19 vaccination.

Post-Covid-19-vaccination adverse events and healthcare utilization among individuals with or without previous SARS-CoV-2 infection

Francisco Tsz Tsun Lai, Lei Huang, Celine Sze Ling Chui, Eric Yuk Fai Wan, Xue Li, Carlos King Ho Wong, Edward Wai Wa Chan, Tiantian Ma, Dawn Hei Lum, Janice Ching Nam Leung, Hao Luo, Esther Wai Yin Chan & Ian Chi Kei Wong


Published: 19 Jan 2022


No safety signal of Covid-19 vaccination was detected from the comparison between vaccine recipients with previous SARS-CoV-2 infection and those without infection.

Carditis After COVID-19 Vaccination With a Messenger RNA Vaccine and an Inactivated Virus Vaccine

Francisco Tsz Tsun Lai, PhD*, Xue Li, PhD*, Kuan Peng, MHS, Lei Huang, MSc, Patrick Ip, MPH, Xinning Tong, PhD, Celine Sze Ling Chui, PhD, Eric Yuk Fai Wan, PhD, Carlos King Ho Wong, PhD, Esther Wai Yin Chan, PhD, David Chung Wah Siu, MD, Ian Chi Kei Wong, PhD


Published: 25th Jan, 2022


Despite a low absolute risk, there is an increased risk for carditis associated with BNT162b2 vaccination. This elevated risk should be weighed against the benefits of vaccination.

Self-reported reactogenicity of CoronaVac (Sinovac) compared with Comirnaty (Pfizer-BioNTech): A prospective cohort study with intensive monitoring

Francisco Tsz Tsun Lai, Miriam Tim Yin Leung, Edward Wai Wa Chan, Lei Huang, Lauren Ka Wun Lau, Kuan Peng, Janice Ching Nam Leung, Min Fan, Kailin Chen, Dawn Hei Lum, Xue Li, Celine Sze Ling Chui, Eric Yuk Fai Wan, Carlos King Ho Wong, Edwin Fung Shing Lam, Terence Yung Yan Cheung, Benjamin John Cowling, Ian Chi Kei Wong, Esther Wai Yin Chan.


Published: 7 February 2022


This post-marketing study comparing the reactogenicity of Covid-19 vaccines suggests a lower risk of self-reported adverse reactions following vaccination with CoronaVac compared with Comirnaty.

COVID-19 vaccines and risks of hematological abnormalities: nested case-control and self-controlled case series study

Chor-Wing Sing PhD ,Casey Tse Lam Tang BSc, Celine Sze Ling Chui PhD, Min Fan MPH, Francisco Tsz Tsun Lai PhD, Xue Li PhD, Eric Yuk Fai Wan PhD, Carlos King Ho Wong PhD, Esther Wai Yin Chan PhD, Ivan Fan Ngai Hung MD, Anskar Yu-Hung Leung MD, Ching-Lung Cheung PhD, Ian Chi Kei Wong PhD


Published: 26 January 2022


There was no association between CoronaVac and hematological abnormalities. The benefits of vaccination against COVID-19 still outweigh the risk of hematological abnormalities.

Herpes zoster related hospitalization after inactivated (CoronaVac) and mRNA (BNT162b2) SARS-CoV-2 vaccination: A self-controlled case series and nested case-control study

Eric Yuk Fai Wan, Celine Sze Ling Chui, Yuan Wang, Vanessa Wai Sei Ng, Vincent Ka Chun Yan, Francisco Tsz Tsun Lai, Xue Li, Carlos King Ho Wong, Esther Wai Yin Chan, Christina Sze Man Wong, Kathy Sze Man Leung, Michael Yuxuan Ni, Sophie Alessandra Valkenburg, Joseph Sriyal Malik Peiris, Joseph Tsz Kei Wu, Benjamin John Cowling, Darren M Ashcroft, Ivan Fan Ngai Hung, Gabriel Matthew Leung, Ian Chi Kei Wong


Published: February 01, 2022


An increased risk of herpes zoster related hospitalization after CoronaVac and BNT162b2 vaccinations was found. However, the absolute risks of such adverse event after CoronaVac and BNT162b2 vaccinations were very low. In locations where COVID-19 is prevalent, the protective effects on COVID-19 from vaccinations will greatly outweigh the potential side effects of vaccination.

Lack of inflammatory bowel disease flare-up following two-dose BNT162b2 vaccine: a population-based cohort study

Xue Li, Xinning Tong, Ian Chi Kei Wong, Kuan Peng, Celine Sze Ling Chui, Francisco Tsz Tsun Lai, Eric Yuk Fai Wan, Carlos King Ho Wong, Wai Keung Leung, Esther Wai Yin Chan


Published: February 08, 2022


Safety of inactivated and mRNA COVID-19 vaccination among patients treated for hypothyroidism: a population-based cohort study

Xi Xiong, Carlos King Ho Wong, Ivan Chi Ho Au, Francisco Tsz Tsun Lai, Xue Li, Eric Yuk Fai Wan, Celine Sze Ling Chui, Esther Wai Yin Chan, Franco Wing Tak Cheng, Kristy Tsz Kwan Lau, Chi Ho Lee, Yu-Cho Woo, David Lui, and Ian Chi Kei Wong


Published: 7 Apr 2022


CoronaVac vaccination is not associated with unstable thyroid status or an increased risk of adverse outcomes among patients treated for hypothyroidism in general. These reassuring data should encourage them to get vaccinated against COVID-19 for protection from potentially worse COVID-19-related outcomes.

Myocarditis Following COVID-19 BNT162b2 Vaccination Among Adolescents in Hong Kong

Xue Li, Francisco Tsz Tsun Lai, Gilbert T. Chua, Mike Yat Wah Kwan, Yu Lung Lau, Patrick Ip, Ian Chi Kei Wong


Published: 25 Feb 2022


Questions remain about the mechanism of myocarditis following mRNA vaccine. Potential ways to reduce myocarditis risk in adolescents could be the use of single-dose only, a lower dosage for 2 doses as recommended for children aged 5 to 11 years, or a lengthened interval between doses. More laboratory, trial, and postmarketing data may become available to answer these questions. Our study expands the current understanding of dose-response relationship and suggests that COVID-19 vaccination recommendations in adolescents may need to be customized rather than standardized to fit all.

Adverse Events of Special Interest Following the Use of BNT162b2 in Adolescents: A Population-Based Retrospective Cohort Study

Francisco Tsz Tsun Lai, Gilbert T Chua, Edward Wai Wa Chan, Lei Huang, Mike Yat Wah Kwan, Tiantian Ma, Xiwen Qin, Celine Sze Ling Chui, Xue Li, Eric Yuk Fai Wan, Carlos King Ho Wong, Esther Wai Yin Chan, Ian Chi Kei Wong, Patrick Ip


Published: 21 March 2022


With myocarditis excluded as AESIs, no significantly elevated risk of AESIs as a composite outcome associated with vaccination was observed. To conclude, the overall absolute risk of AESIs was low with no evidence of an increased risk of AESIs except myocarditis and sleeping disturbances/disorders.


Carlos King Ho Wong, Xi Xiong, Kristy Tsz Kwan Lau, Celine Sze Ling Chui, Francisco Tsz Tsun Lai, Xue Li, Esther Wai Yin Chan, Eric Yuk Fai Wan, Ivan Chi Ho Au, Benjamin John Cowling, Cheuk Kwong Lee & Ian Chi Kei Wong


Published: 17 March 2022


No significant association between delayed second dose of BNT162b2 or CoronaVac and all-cause mortality, ED visit, and unscheduled hospitalization was observed in the present cohort. Regardless of the recommended or delayed schedule for SARS-CoV-2 vaccination, a second dose of both vaccines should be administered to obtain better protection against infection and serious disease. The second dose should be administered within the recommended interval following the manufacturer’s product information, until further studies support the benefits of delaying vaccination outweighing the risks.

Xue Li, Le Gao, Xinning Tong, Vivien K.Y. Chan, Celine S.L. Chu, Francisco T.T. Lai, Carlos K.H. Wong, Eric Y.F. Wan, Esther W.Y. Chan, Kui Kai Lau, Chak Sing Lau, Ian C.K.Wong


Published: 14 Apr 2022


Autoimmune conditions requiring hospital care are rare following mRNA and inactivated COVID-19 vaccination with similar incidence to non-vaccinated individuals. The association between first dose BNT162b2 vaccination and immune-related sleeping disorders requires further research. Population-based robust safety surveillance is essential to detect rare and unexpected vaccine safety events.


Wei Kang, Jessica J. P. Shami, Vincent K. C. Yan, Xuxiao Ye, Joseph E. Blais, Xue Li, Victor H. F. Lee, Celine S. L. Chui, Francisco T. T. Lai, Eric Y. F. Wan, Carlos K. H. Wong, Ian C. K. Wong & Esther W. Chan

Published: 19 May 2022


The incidence of AESI following vaccination with two doses of either BNT162b2 or CoronaVac vaccines was low. The findings of this study can reassure clinicians and patients with cancer about the overall safety of BNT162b2 and CoronaVac in patients with cancer, which could increase the COVID-19 vaccination rate in this vulnerable group of patients.

Eric Yuk Fai Wan, Celine Sze Ling Chui, Vanessa Wai Sei Ng, Yuan Wang, Vincent Ka Chun Yan, Ivan Chun Hang Lam, Min Fan, Francisco Tsz Tsun Lai, Esther Wai Yin Chan, Xue Li, Carlos King Ho Wong, Raccoon Ka Cheong Chung, Benjamin John Cowling, Wing Chi Fong, Alexander Yuk Lun Lau, Vincent Chung Tong Mok, Frank Ling Fung Chan, Cheuk Kwong Lee, Lot Sze Tao Chan, Dawin Lo, Kui Kai Lau, Ivan Fan Ngai Hung, Chak Sing Lau, Gabriel Matthew Leung, Ian Chi Kei Wong,

Published: 8 June 2022



There is an overall increased risk of Bell’s palsy following BNT162b2 vaccination, particularly within the first 14 days after the second dose, but the absolute risk was very low.

Carlos King Ho Wong, Kristy Tsz Kwan Lau, Xi Xiong, Ivan Chi Ho Au, Francisco Tsz Tsun Lai, Eric Yuk Fai Wan, Celine Sze Ling Chui, Xue Li, Esther Wai Yin Chan, Le Gao, Franco Wing Tak Cheng, Sydney Chi Wai Tang, Ian Chi Kei Wong 

Published: 21 June 2022


We observed that the incidences of AESIs (cumulative incidence rate of 0.06%–0.09%) and mortality following the first and second doses of CoronaVac and BNT162b2 vaccination were very low. The safety profiles of the vaccines were generally comparable, except for a significantly higher incidence rate of Bell palsy, but lower incidence rates of anaphylaxis and sleeping disturbance or disorder, following first dose CoronaVac versus BNT162b2 vaccination. Our results could help inform the choice of inactivated COVID-19 vaccines, mainly administered in low- and middle-income countries with large populations, in comparison to the safety of mRNA vaccines. Long-term surveillance on the safety profile of COVID-19 vaccines should continue.

Xuxiao Ye, Tiantian Ma, Joseph E. Blais, Vincent K.C. Yan, Wei Kang, Celine S.L. Chui, Francisco T.T. Lai, Xue Li, Eric Y.F. Wan, Carlos K.H. Wong, Hung-Fat Tse, Chung-Wah Siu, Ian C.K. Wong, Esther W. Chan

Published: 22 June 2022


Our findings showed no evidence of an increased risk of MACE after vaccination with BNT162b2 or CoronaVac in patients with CVD. Future research is required to monitor the risk after the third dose of each vaccine.


Because older age is associated with poor outcomes after SARS-CoV-2 infection, the benefits of CoronaVac vaccination in older adults outweigh the risks in regions where COVID-19 is prevalent. Ongoing monitoring of vaccine safety is warranted.


There was no evidence of an increased risk of ALI associated with BNT162b2 or CoronaVac vaccination. Based on all current available evidence from previous studies and our study, the benefit of mass vaccination far outweighs the ALI risk from vaccination and SARS-CoV-2 infection.