Comparative analysis of symptom profile and risk of death associated with infection by SARS-CoV-2 and its variants in Hong Kong (preprint)

Introduction: The recurrent multi-wave nature of COVID-19 necessitates updating its symptomatology. Before the omicron era, Hong Kong was relatively unscathed and had a low vaccine uptake rate among the old-old, giving us an opportunity to study the intrinsic severity of SARS-CoV-2 variants. A comparison of symptom patterns across variants and vaccination status in Hong Kong has yet to be undertaken. The intrinsic severity of variants and symptoms predictive of severe outcomes are also understudied as COVID-19 evolves. We therefore aim to characterize the effect of variants on symptom presentation, identify the symptoms predictive and protective of death, and quantify the effect of vaccination on symptom development. Methods: With the COVID-19 case series in Hong Kong from inception to 25 August 2022, an iterative multi-tier text-matching algorithm was developed to identify symptoms from free text. Cases were fully vaccinated if they completed two doses. Multivariate regression was used to measure associations between variants, symptom development, death and vaccination status. A least absolute shrinkage and selection operator technique was used to identify a parsimonious set of symptoms jointly associated with death. Results: Overall, 70.9% (54450/76762) of cases were symptomatic. We identified a wide spectrum of symptoms (n=102), with cough, fever, runny nose and sore throat being the most common (8.16-47.0%). Intrinsically, the wild-type and delta variant caused similar symptoms, with runny nose, sore throat, itchy throat and headache more frequent in the delta cohort; whereas symptoms were heterogeneous between the wild-type and omicron variant, with seven symptoms (fatigue, fever, chest pain, runny nose, sputum production, nausea/vomiting and sore throat) more frequent in the omicron cohort. With full vaccination, omicron was still more likely than delta to cause fever. Fever, blocked nose and shortness of breath were robustly jointly predictive of death as the virus evolved. Number of vaccine doses required for reduction in occurrence varied by symptoms. Discussion: This is the first large-scale study to evaluate the changing symptomatology by COVID-19 variants and vaccination status using free-text reporting by patients. We substantiate existing findings that omicron has a different clinical presentation compared to previous variants. Syndromic surveillance can be bettered with reduced reliance on symptom-based case identification, increased weighing on symptoms robustly predictive of mortality in outcome prediction, strengthened infection control in care homes through universal individual-based risk assessment to enable early risk stratification, adjusting the stockpile of medicine to tally with the changing symptom profiles across vaccine doses, and incorporating free-text symptom reporting by patients.

A randomized controlled trial of an educational intervention in willingness of the COVID-19 vaccine booster shots among non-healthcare workers

IntroductionDespite a high proportion of workers infected with SARS-CoV-2 experienced no or mild symptoms, the business ought to shut down when there is an outbreak. Observational studies showed that willingness of COVID-19 vaccine increased vaccination rate. Although receiving booster shots may reduce infection and release symptoms, the public has concerns on booster vaccines and whether educational intervention improves the willingness remains unclear. This study aimed to evaluate the effectiveness of a theory-based educational programme on improving willingness intention/actual uptake of booster doses and reducing infection in non-healthcare workers.Materials and MethodsThis is an ongoing 9-month randomized controlled trial (RCT) with two arms and single blinding. From April to June 2022, 299 workers enrolled from a variety of work settings were randomly allocated to intervention and control group. Intervention was an online educational programme based on the theory of planned behavior (TPB), which was implemented at the beginning and repeated at 3-month. The outcomes were changes of willingness intention/actual uptake of booster vaccine and infection, measured at pre- and post- intervention of baseline, at 3-month, 6-month and 9-month follow-up. The ethics approval number is CREC-2021.531-T.ResultsAt the baseline, about 61% workers received 3 doses and 38% had ever been infected with SARS-CoV-2. Compared with the pre-intervention, both the post-intervention and control group had improved attitude (26.5±9.4 vs 26.7±9.4) and perceived behavioral control (30.7±8.1 vs 29.5±8.5), with a slightly better for the intervention group. These scores decreased slightly at 3-month intervention (28.7±8.7 vs 28.7±8.9), but they were still higher than the pre-intervention measurements. A similar pattern was observed for willingness intention to uptake booster doses but not for the infection rate.ConclusionsThis RCT shows that education intervention increased willingness of getting booster shots via improving attitude and perceived behavior control, but the effect was not significant. [HMRF#COVID1903008, shelly@cuhk.edu.hk]

Breakthrough infection among workers in different non-healthcare working settings

IntroductionWorkplace is supposed to be an important transmission node of coronavirus disease-2019 (COVID-19) in the epic initiation. Assessing the contagious risk in the different workplaces is important to target effective measures workplace. However, there was limited data to explore transmission patterns in work settings after COVID-19 spread into the community and population vaccination.Materials and MethodsFrom April to June 2022, 328 workers were enrolled in a variety of work settings. An online questionnaire was used to collect their current work industry, geographic information, vaccination of SARS-CoV-2, infection, etc. To categorize their exposure risk to COVID-19 cases from the workplace, workers were grouped into 3 different work settings according to their job nature and working environment. Non-office workers were those who normally carried out their jobs in a range of environments in an indoor or outdoor working space where close contact with the general public is frequent;Mobile workers were those who frequently move for conducting business that involves closer and more frequent contact with the general public;Office workers were those normally carry out professional duties and administrative work in an indoor working space. Breakthrough infection is defined as an infection after 14 days of full vaccination. The ethics approval number is CREC-2021.531-T.ResultsThere were 97, 151, and 80 workers in mobile, non-office, and office work groups and the infection rate were 40.2%, 40.4%, and 37.5%, respectively. 96.3% of them were full-vaccinated or get a booster shot. There was no significant difference in the breakthrough infection rate of workers in these three work settings no matter getting two or three shots of vaccine.ConclusionsWorkplace infection especially after full vaccination is not an important SARS-CoV-2 transmission pathway. [HMRF#COVID1903008, shelly@cuhk.edu.hk]

Public perceptions and preventive behaviours during the early phase of the COVID-19 pandemic: a comparative study between Hong Kong and the United Kingdom (preprint)

BackgroundIn the absence of treatments and vaccines, the mitigation of COVID-19 relies on population engagement in non-pharmaceutical interventions, which is driven by their risk perception, anxiety level and knowledge. There may also be regional discrepancies in these drivers due to different historical exposure to disease outbreaks, government responses and cultures. As such, this study compared psycho-behavioral responses in two regions during the early phase of the pandemic. MethodsComparable cross-sectional surveys were administered among adults in Hong Kong (HK) and the United Kingdom (UK) during the early phase of each respective epidemic. Explanatory variables included demographics, risk perception and knowledge of COVID-19, anxiety level and preventive behaviors. Responses were weighted according to census data. Logistic regression models, including interaction terms to quantify regional differences, were used to assess the association between explanatory variables and the adoption of social-distancing measures. ResultsData of 3431 complete responses (HK:1663; UK:1768) were analysed. Perceived severity differed by region (HK: 97.5%; UK: 20.7%). A large proportion of respondents were abnormally/borderline anxious (HK:64.8%; UK:45.9%) and regarded direct contact with infected individuals as the transmission route of COVID-19 (HK:94.0-98.5%; UK:69.2-93.5%), with HK identifying additional routes. HK reported high levels of adoption of social-distancing (HK:32.4-93.7%; UK:17.6-59.0%) and mask-wearing (HK:98.8%; UK:3.1%). The impact of perceived severity and perceived ease of transmission on the adoption of social-distancing varied by region. In HK, they had no impact, whereas in the UK, those who perceived severity as "high" were more likely to adopt social-distancing (aOR:1.58-3.01), and those who perceived transmission as "easy" were prone to both general social-distancing (aOR:2.00, 95% CI:1.57, 2.55) and contact avoidance (aOR:1.80, 95% CI: 1.41, 2.30). The impact of anxiety on adopting social-distancing did not vary by region. DiscussionThese results suggest that health officials should ascertain and consider baseline levels of risk perception and knowledge in the populations, as well as prior sensitisation to infectious disease outbreaks, during the development of mitigation strategies. Risk communication should be done through suitable media channels - and trust should be maintained - while early intervention remains the cornerstone of effective outbreak response.

Are we ready when COVID-19 vaccine is available? Study on nurses' vaccine hesitancy in Hong Kong (preprint)

Introduction: Nurses are considered a trustworthy source of vaccine-related information to build public confidence in vaccination. This study estimated nurses' influenza vaccine uptake and intention to receive COVID-19 vaccine when available, and examined the corresponding psychological antecedents. Methods : A cross-sectional online survey among nurses was conducted during the main COVID-19 outbreak in Hong Kong between mid-March and late April 2020. Demographics, influenza vaccination, intention to have COVID-19 vaccine, the 5C vaccine hesitancy components (i.e., confidence, complacency, constraints, calculation, and collective responsibility), work stress and COVID-related work demands (i.e., insufficient supply of personal protective equipment, involvement in isolation rooms, and unfavorable attitudes towards workplace infection control policies) were reported. Results: The influenza vaccination coverage and the proportion intending to take COVID-19 vaccine were 49% and 63%, respectively, among 1205 eligible nurses. Influenza vaccine uptake was associated with working in public hospitals and all 5C constructs, whereas stronger COVID-19 vaccination intention was associated with younger age, more confidence, less complacency and more collective responsibility towards the vaccine. COVID-19-related demands were associated with greater work stress, and hence stronger COVID-19 vaccination intention. Conclusion: Vaccine uptake/intention was well predicted by the 5C constructs. With less work stress among nurses in the post-pandemic period, the intention to take COVID-19 vaccine will likely drop. The 5C constructs should be infused in vaccination campaigns. While a COVID-19 vaccine could be ready soon, communities are not ready to accept it. More research work is needed to boost the uptake.

Availability of workplace policy for prevention of coronavirus disease 2019 and its relationship with personal protection behaviours: A survey of employees (preprint)

Background: The evolving pandemic of coronavirus disease 2019 (COVID-19) has become a severe threat to public health, and the workplace presents high risks in terms of spreading the disease. Few studies have focused on the impact of workplace policy on individual behaviours. This study aimed to examine the relationship of workplace guidelines and measures with employees’ behaviours regarding COVID-19 prevention. Methods: A cross-sectional survey using an online questionnaire was conducted to gather employees’ access to workplace guidelines and measures as well as their personal protection behaviours. Statistical associations between these two factors in different occupations were examined using multiple ordinal logistic regressions. Results: A total of 1048 valid questionnaires across five occupational groups were analysed. Manual labourers reported lower availability of workplace guidelines and measures (76.9% vs. 89.9% for all, P = 0.003). Employees with available workplace guidelines and measures performed personal protection behaviours with higher frequency, and this association was more significant among managers/administrators and manual labourers. Conclusions: Awareness about the disease and pandemic among employers and administrators should be promoted, and resources should be allocated to publish guidelines and implement measures in the workplace. Manual labourers may require specific attention regarding accessibility of relevant information, given their poorer experience of workplace policy and their work nature. Governments should guide the establishment of appropriate policies and responses at the workplace level. Further studies are needed to test the effectiveness of specific workplace policies on COVID-19 prevention.