To the Editor—We previously summarised cases involving filicide in Hong Kong between 2017 and 2018.1 These cases involved children mostly aged <12 years and parents of both sexes with multi-dimensional causal factors.2 Generally, it is crucial to understand the motivation of perpetrators to provide early assessment and intervention. Systematic collection of data on filicide could elucidate these motivations and bring new insights to clinical practice; however, few countries (eg, Australia, Canada) have an official registry on filicide. We recommend setting up an official filicide registry in Hong Kong to investigate the risk factors associated with filicide in Hong Kong in order to inform early assessment and intervention as well as policy decisions. The Comprehensive Child Development Service under Hospital Authority, Department of Health, Social Welfare Department, Education Bureau and Labour and Welfare Bureau aims to identify needs of at-risk children and families in Hong Kong.3

Moreover, depression, related to loneliness, helplessness, or hopelessness, is one psychological condition present in those who committed filicides.2 4 Perpetrators might exhibit help-seeking behaviour or filicidal tendencies. Unfortunately, mental health support in Hong Kong is lacking, especially in terms of caregiver support, although it is no substitute for a strong social support network.1 Physicians may have the opportunity to prevent filicide if these warning signs can be detected.5 We recommend development of a multi-dimensional and systematic screening tool to help healthcare professionals in identifying potential cases for filicide risk.1 Physicians, especially psychiatrists, and other healthcare and social service professionals could seize the opportunity to prevent filicide if early warning signs can be identified.5

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

As an editor of the journal, KL Hon was not involved in the peer review process. Other authors have no conflicts of interest to disclose.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. Hon KL. Dying with parents: an extreme form of child abuse. World J Pediatr 2011;7:266-8. Crossref

2. Tang D, Siu B. Maternal infanticide and filicide in a psychiatric custodial institution in Hong Kong. East Asian Arch Psychiatry 2018;28:139-43.

3. Education Bureau. Comprehensive Child Development Service. Hong Kong SAR Government 2018. Available from: https://www.edb.gov.hk/en/edu-system/preprimary-kindergarten/comprehensive-child-development-service/index.html. Accessed 21 Sep 2022.

4. Hon KL, Chan CH, Chan L. Filicides in Hong Kong. HK J Paediatr (New Series) 2019;24:48-50.

5. Klier CM, Fisher J, Chandra PS, Spinelli M. Filicide research in the twenty-first century. Arch Womens Ment Health 2019;22:135-7. Crossref

To the Editor—We have previously published our observations on changes to the pattern of elderly abuse in 2020 (during the coronavirus disease 2019 [COVID-19] pandemic) compared with the pre-pandemic period.1 There was a proportionate increase in physical abuse with the spouse as perpetrator. With the publication of additional data by the Social Welfare Department, we have obtained further data relating to elder abuse between 2014 and March 2022 (n=4293).2 We compared data reported during the COVID-19 pandemic from 2020 to March 2022 (n=996) with pre-pandemic data (from 2014 to 2019, n=3297). The abuse methods and identity of perpetrator were compared using Chi squared statistics. The data are summarised in the Table.

There was proportionately more physical abuse (71.6% vs 65.9%, χ²=11.0774, P=0.009) but less financial abuse (8.2% vs 16.2%, χ²=39.4716, P<0.001) during the pandemic compared with the pre-pandemic period. Regarding the perpetrators, there were proportionately more spouses (64.8% vs 54.7%, χ²=31.8566, P<0.001). There was no difference in the pattern of elderly abuse or identity of perpetrators within the COVID-19 pandemic period (ie, 2020 to March 2022).

We continued to observe proportionately more physical abuse with the spouse as perpetrator during the pandemic. It is likely the initially low vaccination uptake among older adults and COVID-19 outbreak meant the older adults were more likely to remain at home. There were insufficient opportunities for recreational activities or social support. A spouse, often the only co-habitee, had more opportunities to inflict abuse. Government and social welfare organisations should be alerted to this change.

All authors contributed to the drafting of the letter and critical revision for important intellectual content. All authors approved the final version for publication and take responsibility for its accuracy and integrity.

As an editor of the journal, JKH Luk was not involved in the peer review process. Other authors have disclosed no conflicts of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. Ip CT, Shea YF, Chan HW, Luk KH. Changes in pattern of elderly abuse during COVID-19 pandemic. Psychogeriatrics 2022;22:286-7. Crossref

2. Social Welfare Department, Hong Kong SAR Government. Services for prevention and handling of elder abuse. 2022. Available from: https://www.swd.gov.hk/en/index/site_pubsvc/page_elderly/sub_csselderly/id_serabuseelder/.Accessed 12 May 2022.

To the Editor—A recent press release issued by the Department of Health of the Hong Kong SAR Government urged public not to buy or consume an oral health supplement “HemoHIM”.1 This product has been withdrawn from the market in Hong Kong, Taiwan and Singapore. In Hong Kong, from April to September 2021, four women presented to public hospitals because of acute hepatitis (Table).2 All patients had consumed a health supplement named HemoHIM (Atomy; Gongju, South Korea) and liver function improved after cessation of use. No alternative medical causes were identified. A sample of HemoHIM was analysed by high-performance liquid chromatography with diode-array detection and liquid chromatography–tandem mass spectrometry, revealing the presence of methoxsalen, psoralen, and benign herbal markers. Subsequent analysis of additional samples from different sources showed consistent laboratory findings. Methoxsalen (also known as 8-methoxypsoralen, 8-MOP) and psoralen are naturally occurring furocoumarins. They can be found in a number of plant species at various concentrations and are collectively referred to as psoralens. Psoralens have photosensitising property, thus methoxsalen is formulated as drugs used in PUVA (Psoralen and ultraviolet light UVA) treatment for psoriasis and vitiligo.3 Psoralens bind to DNA when exposed to ultraviolet light, inhibiting DNA synthesis and causing a decrease in cell proliferation. Methoxsalen- and psoralen-containing herbs have been reported to cause liver injuries.3 4 The listed herbal ingredients of HemHIM should not contain psoralen or methoxsalen. Further investigations are needed to explain the occurrence of these chemical compounds in the product. Several plant species used in traditional Chinese medicine have been reported to contain psoralens,5 including Fructus Psoraleae (補骨脂, the dried seeds of Psoralea corylifolia), which contains a relatively high concentration of psoralens.2 3 Frontline doctors should be vigilant to patients presenting with symptoms of liver injury after consumption of HemoHIM or other supplements containing Fructus Psoraleae.

CK Chan drafted the letter and all authors contributed to the critical revision of the letter for important intellectual content. All authors approved the final version for publication and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. Hong Kong SAR Government. DH investigates suspected poisoning cases relating to oral product “HemoHIM”. 1 Nov 2021. Available from: https://www.info.gov.hk/gia/general/202111/01/P2021110100785.htm. Accessed 15 Nov 2021.

2. LiverTox: clinical and research information on drug-induced liver injury. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-. Roussel Uclaf Causality Assessment Method (RUCAM) in drug induced liver injury. Updated 4 May 2019. Available from: https://www.ncbi.nlm.nih.gov/books/NBK548272/. Accessed 15 Nov 2021.

3. Cheung WI, Tse ML, Ngan T, et al. Liver injury associated with the use of Fructus Psoraleae (Bol-gol-zhee or Bu-gu-zhi) and its related proprietary medicine. Clin Toxicol (Phila) 2009;47:683-5. Crossref

4. Li A, Gao M, Zhao N, Li P, Zhu J, Li W. Acute liver failure associated with Fructus Psoraleae: a case report and literature review. BMC Complement Altern Med 2019;19:84. Crossref

5. Guo Jia Zhong Yi Yao Guan Li Ju “Zhonghua Ben Cao” Bian Wei Hui. Zhong Hua Ben Cao (中華本草) [in Chinese]. Shanghai: Shanghai Ke Xue Ji Shu Chu Ban She; 1999.

To the Editor—We previously reported serological findings of 302 healthcare workers (HCWs) who completed two doses of mRNA (BNT162b2/Comirnaty; Fosun-BioNTech Pharma) and inactivated COVID-19 vaccine (CoronaVac; Sinovac Life Sciences, Beijing, China).1 Both vaccines were found to be immunogenic in the majority of HCWs. The BNT162b2 resulted in a 11-fold higher level of anti-spike IgG (Abbott SARS-CoV-2 IgG II Quant assay, mean=11572.6 AU/mL vs 1005.2 AU/mL; P<0.001) and a higher surrogate neutralising antibody (sNAb) [GenScript cPass SARS-CoV-2 Surrogate Virus Neutralization Test Kit] positive rate (100% vs 94.4%; P<0.001).

We report week 12 serological data of our cohort. Among 197 CoronaVac and 100 BNT162b2 recipients, baseline characteristics of the two vaccine arms were comparable except sex (60.9% and 38% female in CoronaVac and BNT162b2, respectively) [online supplementary Table 1]. There was no difference in anti-spike immunoglobulin G (IgG) positive rate at week 12 (98.5% in CoronaVac vs 99% in BNT162b2; P=1) [Table 1]. Waning of IgG level was observed in both vaccine arms with a larger magnitude of decline in BNT162b2 (-72% vs -64.6%; P<0.001). Despite the more pronounced decline, the median anti-spike IgG of BNT162b2 remained 11-fold higher than that of CoronaVac at week 12 (2840.25 AU/mL vs 253.60 AU/mL; P<0.001).

Decline in sNAb was also observed in both arms but the magnitude was significantly smaller in BNT162b2 (-28.3% in CoronaVac vs -2.3% in BNT162b2; P<0.001). Using the manufacturer’s positive cut-off at 30% signal inhibition or above, significantly more CoronaVac recipients had lost their sNAb at week 12 (94.4% sNAb positive at week 2, 62.4% at week 12) whereas 99% of BNT162b2 recipients remained sNAb positive. Throughout the three time points, BNT162b2 arm had higher levels of anti-spike IgG and sNAb (P<0.001) [Fig].

Among the 286 HCWs who had positive sNAb after two doses of vaccine, 64 had lost their sNAb while 222 had sustained sNAb at week 12. Sustained sNAb at week 12 were associated with younger age, BNT162b2 and higher antibody at any time point (Table 2). Multivariate logistic regression analysis showed that only higher IgG and sNAb level at 2 weeks after the second dose were significantly associated with sustained sNAb at week 12 (online supplementary Table 2).

These results demonstrate rapid antibody decline after both mRNA and inactivated vaccine with a more durable sNAb in the BNT162b2 arm. However, further studies are needed to clarify the impact of waning antibody on vaccine efficacy and protection against severe infection.

Concept or design: All authors.
Acquisition of data: All authors.
Analysis or interpretation of data: All authors.
Drafting of the manuscript: JST Zee.
Critical revision of the manuscript for important intellectual content: All authors.

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

The authors acknowledge the excellent work and contributions by staff at the Clinical Pathology Laboratory of Hong Kong Sanatorium & Hospital.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

This study obtained ethics approval (Ref RC-2021-07) from the Research Ethics Committee of the Hong Kong Sanatorium & Hospital Medical Group.

1. Zee JS, Lai KT, Ho MK, et al. Serological response to mRNA and inactivated COVID-19 vaccine in healthcare workers in Hong Kong: preliminary results. Hong Kong Med J 2021;27:312-3. Crossref

To the Editor—We read with interest the recent Editorial on gross negligence manslaughter.1 The third defendant in “DR” was employed by a clinic. She intravenously administered to healthy clients processed cells originally harvested from the client. The deceased received infusion on 3 October 2012 and passed away on 10 October from multiorgan failure due to septic shock caused by Mycobacterium abscessus. The indictment provided, inter alia2:

1. the therapy was experimental for cancer patients, with unproven or uncertain efficacy;
2. there was no scientifically proven benefit on healthy patients;
3. the preparation involved prolonged culturing of blood cells with risk of contamination.

Any intravenous infusion outside a research setting must either be a registered pharmaceutical product of good manufacturing practice standard or comply with stringent quality requirements of a national blood transfusion service. It is foreseeable by any medical practitioner that lack of assurance of sterility would result in microbial contamination. Consideration through hindsight is not involved.

The Rose case is distinguishable.3 An optometrist performed routine eye examination for a 7-year-old on 15 February 2012, without retinal examination, which would have revealed papilloedema. Five months later, the boy passed away suddenly. The Court of Appeal quashed the gross negligence manslaughter conviction, as the boy was asymptomatic “with no material pre-existing history” in February; the significance of retinal examination was only realised with hindsight.3 We respectfully submit that the DR decision was consistent with the established gross negligence manslaughter law, with no significant ambiguity. Medical practitioners managing patients in accordance with standard medical practices would unlikely face criminal sanction.

Both authors contributed to the drafting of the letter and critical revision for important intellectual content. Both authors approved the final version for publication and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. Leung GK. Medical manslaughter: the role of hindsight. Hong Kong Med J 2021;27:240-1. Crossref

2. HKSAR v Mak Wan Ling. HKCFI 3069; 2020. Available from: https://legalref.judiciary.hk/lrs/common/search/search_result_detail_frame.jsp?DIS=132426&QS=%28mak%2Bwan%2Bling%29&TP=RS. Accessed 23 Aug 2021.

3. Regina v Rose HM. EWCA Crim 1168; 2017. Available from: https://www.bailii.org/ew/cases/EWCA/Crim/2017/1168.html. Accessed 23 Aug 2021.