mRNA-based COVID-19 booster vaccination is highly effective and cost-effective in Australia (preprint)

Background: Australia implemented an mRNA-based booster vaccination strategy against the COVID-19 Omicron variant in November 2021. We aimed to evaluate the effectiveness and cost-effectiveness of the booster strategy over 180 days. Methods: We developed a decision-analytic Markov model of COVID-19 to evaluate the cost-effectiveness of a booster strategy (administered 3 months after 2nd dose) in those aged [≥]16 years in Australia from a healthcare system perspective. The willingness-to-pay threshold was chosen as A$ 50,000. Findings: Compared with 2-doses of COVID-19 vaccines without a booster, Australia's booster strategy would incur an additional cost of A$0.88 billion but save A$1.28 billion in direct medical cost and gain 670 quality-adjusted life years (QALYs) in 180 days of its implementation. This suggested the booster strategy is cost-saving, corresponding to a benefit-cost ratio of 1.45 and a net monetary benefit of A$0.43 billion. The strategy would prevent 1.32 million new infections, 65,170 hospitalisations, 6,927 ICU admissions and 1,348 deaths from COVID-19 in 180 days. Further, a universal booster strategy of having all individuals vaccinated with the booster shot immediately once their eligibility is met would have resulted in a gain of 1,599 QALYs, a net monetary benefit of A$1.46 billion and a benefit-cost ratio of 1.95 in 180 days. Interpretation: The COVID-19 booster strategy implemented in Australia is likely to be effective and cost-effective for the Omicron epidemic. Universal booster vaccination would have further improved its effectiveness and cost-effectiveness.

Long-term Improvement of Air Quality Associated with Lung Function Benefits in Chinese Young Adults: A Quasi-experiment Cohort Study (preprint)

Background: Long-term exposure to air pollution is associated with lung function impairment. However, whether long-term improvements in air quality could improve lung function is unclear. Methods: : We conducted a prospective quasi-experiment cohort study with 1731 college students in Shandong, China from September 2019 to September 2020, covering COVID-19 lockdown period. Data on PM 2.5 , PM 10 , NO 2 and SO 2 concentrations were obtained from China Environmental Monitoring Station. The concentration of O3 was obtained from Tracking Air Pollution in China. Lung function indicators included forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and forced expiratory flow at 50% of FVC (FEF50%). Linear mixed-effects model was used to examine the associations between the change of air pollutants’ concentrations and the change of lung functions. We also conducted stratified analysis by sex. Results: : Compared with 2019, the mean FVC, FEV1 and FEF50% were elevated by 414.4ml, 321.5ml, and 28.4ml respectively in 2020. Every 5μg/m 3 decrease in annual average PM 2.5 concentrations was associated with 36.0ml [95% confidence interval (CI):6.0, 66.0ml], 46.1ml (95% CI:16.7, 75.5ml), and 124.2ml/s (95% CI:69.5, 178.9ml/s) increment in the FVC, FEV1, and FEF50%, respectively. Similar associations were found for PM 10 . There was no significant effect difference between male and female. Conclusions: : Long-term improvement of air quality can improve lung function among young adults. Stricter policies on improving air quality are needed to protect human health. Funding Taishan Scholar Program

Projected COVID-19 epidemic in the United States in the context of the effectiveness of a potential vaccine and implications for social distancing and face mask use (preprint)

BackgroundMultiple candidates of COVID-19 vaccines have entered Phase III clinical trials in the United States (US). There is growing optimism that social distancing restrictions and face mask requirements could be eased with widespread vaccine adoption soon. MethodsWe developed a dynamic compartmental model of COVID-19 transmission for the four most severely affected states (New York, Texas, Florida, and California). We evaluated the vaccine effectiveness and coverage required to suppress the COVID-19 epidemic in scenarios when social contact was to return to pre-pandemic levels and face mask use was reduced. Daily and cumulative COVID-19 infection and death cases were obtained from the Johns Hopkins University Coronavirus resource center and used for model calibration. ResultsWithout a vaccine, the spread of COVID-19 could be suppressed in these states by maintaining strict social distancing measures and face mask use levels. But relaxing social distancing restrictions to the pre-pandemic level without changing the current face mask use would lead to a new COVID-19 outbreak, resulting in 0.8-4 million infections and 15,000-240,000 deaths across these four states over the next 12 months. In this scenario, introducing a vaccine would partially offset this negative impact even if the vaccine effectiveness and coverage are relatively low. However, if face mask use is reduced by 50%, a vaccine that is only 50% effective (weak vaccine) would require coverage of 55-94% to suppress the epidemic in these states. A vaccine that is 80% effective (moderate vaccine) would only require 32-57% coverage to suppress the epidemic. In contrast, if face mask usage stops completely, a weak vaccine would not suppress the epidemic, and further major outbreaks would occur. A moderate vaccine with coverage of 48-78% or a strong vaccine (100% effective) with coverage of 33-58% would be required to suppress the epidemic. Delaying vaccination rollout for 1-2 months would not substantially alter the epidemic trend if the current interventions are maintained. ConclusionsThe degree to which the US population can relax social distancing restrictions and face mask use will depend greatly on the effectiveness and coverage of a potential COVID-19 vaccine if future epidemics are to be prevented. Only a highly effective vaccine will enable the US population to return to life as it was before the pandemic.

Effects of New York's Executive Order on Face Mask Use on COVID-19 Infections and Mortality: A Modeling Study (preprint)

Background: New York City (NYC) was the epicenter of the COVID-19 pandemic in the United States. On April 17, 2020, the State of New York implemented an Executive Order that requires all people in New York to wear a face mask or covering in public settings where social distancing cannot be maintained. It is unclear how this Executive Order has affected the spread of COVID-19 in NYC. Methods: A dynamic compartmental model of COVID-19 transmission among NYC residents was developed to assess the effect of the Executive Order on face mask use on infections and deaths due to COVID-19 in NYC. Data on daily and cumulative COVID-19 infections and deaths were obtained from the NYC Department of Health and Mental Hygiene. Results: The Executive Order on face mask use is estimated to avert 99,517 (95% CIs: 72,723-126,312) COVID-19 infections and 7,978 (5,692-10,265) deaths in NYC. If the Executive Order was implemented one week earlier (on April 10), the averted infections and deaths would be 111,475 (81,593-141,356) and 9,017 (6,446-11,589), respectively. If the Executive Order was implemented two weeks earlier (on April 3 when the Centers for Disease Control and Prevention recommended face mask use), the averted infections and deaths would be 128,598 (94,373-162,824) and 10,515 (7,540-13,489), respectively. Conclusions: New York's Executive Order on face mask use is projected to have significantly reduced the spread of COVID-19 in NYC. Implementing the Executive Order at an earlier date would avert even more COVID-19 infections and deaths.

The Association between Cold Temperature and Mortality During and Before the COVID-19 Pandemic in Italy: A Nationwide Time-Stratified Case-Crossover Study (preprint)

Background: The coronavirus disease 2019 (COVID-19) pandemic and related containment measures have changed human lives and behaviours. Whether the pandemic could change the association between cold temperature and mortality remains unknown. We aimed to assess whether the association between cold temperature and all-cause mortality in the pandemic period has changed or not compared to the non-COVID-19 period (2015-2019) in Italy.Methods: We collected daily all-cause mortality data and meteorological data for 107 Italian provinces from 1, January 2015 to 31, May 2020. A time-stratified case-crossover design with the distributed lag non-linear model was used to examine the association between cold temperature and all-cause mortality during the first three months (from March to May in 2020) of the COVID-19 outbreak and the same months in 2015-2019.Findings: The relative risk (RR) of all-cause mortality at extreme cold temperature (4 ˚C) in comparison with the minimum mortality temperature (24 ˚C) was 4·75 [95% confidence interval (CI): 3·90-5·79] in the pandemic period, which is more than triple higher than RR [1·41 (95%CI: 1·33-1·50)] in the same months during 2015-2019. The shift in cold-mortality association was particularly significant for people aged 65-74 years [RR (95%CI): 5·98 (3·78-9·46) in 2020 versus 1·29 (1·10-1·51) in 2015-2019], 75-84 years [5·25 (3·79-7·26) versus 1·40 (1·25-1·56)], and ≥ 85 years [5·03 (3·90-6·51) versus 1·52 (1·39-1·66)], but not significant for those aged 0-64 years [1·95 (1·17-3·24) versus 1·24 (1·05-1·48)].Interpretation: The findings suggest that the COVID-19 pandemic enhanced the risk of cold temperature on mortality in Italy, particularly among the elderly people. Further studies are warranted to understand the exact mechanism when detailed data are available.Funding: YG was supported by a Career Development Fellowship of the Australian National Health and Medical Research Council (#APP1107107 & #APP1163693). SL was supported by an Early Career Fellowship of Australian National Health and Medical Research Council (#APP1109193). RX and TY were supported by China Scholarship Council (201806010405, 201906320051). Declaration of Interests: None.Ethics Approval Statement: This study was approved by the School of Public Health and Preventive Medicine, Monash University.

Vulnerability and burden of all-cause mortality associated with particulate air pollution increased during COVID-19 pandemic: a nationwide observed study in Italy (preprint)

Abstract Background: Limited evidence is available on the health effects of particulate matter (i.e. PM2.5, particulate matter with an aerodynamic diameter < 2.5m; PM10, < 10m; PM2.5-10, 2.5-10m) during the pandemic of COVID-19 in Italy. Objectives: To examine the associations between all-cause mortality and daily PM2.5, PM2.5-10, and PM10 in the pandemic period, and compare them to the normal periods (2015-2019) in Italy. Methods: We collected daily data regarding all-cause (stratified by age and gender), and PM2.5, PM2.5-10, and PM10 for 107 Italian provinces from 1, January 2015 to 31, May 2020. A time-stratified case-cross design with the distributed lag non-linear model was used to examine the association between PM and all-cause mortality during the first three months of the COVID-19 outbreak (March to May in 2020) and the same months in 2015-2019. We also compared the counts and fractions of death attributable to PM in two periods. Results: Overall, Italy saw an increase in daily death counts while slight decreases in PM concentrations in 2020 pandemic period compared to same months of 2015-2019. Mortality effects were significant in lag 0-3 days for PM2.5, lag 0-2 for PM10, and lag 0-1 for PM2.5-10. Each 10 g/m3 increase in PM was associated much higher increase in daily all-cause mortality during 2020 pandemic period compared to the same months during 2015-2019 [increased mortality rate: 7.24 % (95%CI: 4.84%, 9.70%) versus 1.69% (95%CI: 1.12%, 2.25%) for PM2.5; 3.45 % (95%C: 2.58%, 4.34%) versus 1.11% (95%CI: 0.79%, 1.42%) for PM10, 4.25% (95%CI: 2.99%, 5.52%) versus 1.76% (95%CI: 1.14%, 2.38%) for PM2.5-10]. The counts and fractions of deaths attributable to PM were higher in 2020 than the normal periods for PM2.5 (attributable death counts: 20,062 in 2020 versus 3,927 per year in 2015-2019; attributable fractions: 10.2% versus 2.4%), PM10 (15,112 versus 3,999; 7.7% versus 2.5%), and PM2.5-10 (7,193 versus 2303; 3.7% versus 1.4%). Conclusions: COVID-19 pandemic increased the vulnerability and excess cases of all-cause mortality associated with short-term exposure to PM2.5, PM2.5-10 and PM10 in Italy, despite a decline in air pollution level. This suggests using historical PM-mortality association to calculate health benefits associated with reduction in PMs has big uncertainties.

COVID-19 pandemic increased the magnitude of mortality risks associated with cold temperature in Italy: A nationwide time-stratified case-crossover study (preprint)

Abstract Backgrounds: The coronavirus disease 2019 (COVID-19) pandemic and some containment measures have changed many people lives and behaviours. Whether the pandemic could change the association between cold temperature and mortality remains unknown. Objectives: We aimed to assess whether the association between cold temperature and all-cause mortality in the pandemic period has changed compared to non-COVID-19 period (2015-2019) in Italy. Methods: We collected daily all-cause mortality data and meteorological data for 107 Italian provinces from 1, January 2015 to 31, May 2020. A time-stratified case-crossover design with the distributed lag non-linear model was used to examine the association between cold temperature and all-cause mortality during the first three months (from March to May in 2020) of the COVID-19 outbreak and the same months in 2015-2019. Results: The relative risk (RR) of all-cause mortality at extreme cold temperature (2.5th percentile of temperature at 3 {degrees}C) in comparison with the minimum mortality temperature (24 {degrees}C) was 4.75 [95% confidence interval (CI): 3.90-5.79] in the pandemic period, which is more than triple higher than RR [1.41 (95%CI: 1.33-1.50)] in the same months during 2015-2019. The shift in cold-mortality association was particularly significant for people aged 65-74 years [RR (95%CI): 5.98 (3.78-9.46) in 2020 versus 1.29 (1.10-1.51) in 2015-2019], 75-84 years [5.25 (3.79-7.26) versus 1.40 (1.25-1.56)], and [≥] 85 years [5.03 (3.90-6.51) versus 1.52 (1.39-1.66)], but not significant for those aged 0-64 years [1.95 (1.17-3.24) versus 1.24 (1.05-1.48)]. Conclusion: The findings suggest that the COVID-19 pandemic enhanced the risk of cold temperature on mortality in Italy, particularly among the elderly people. Further studies are warranted to understand the exact mechanism when detailed data are available.

Epidemiological and clinical characteristics of COVID-19 in adolescents and young adults (preprint)

Background: Adolescents and young adults might play a key role in the worldwide spread of Coronavirus Disease 2019 (COVID-19), because they are more involved in overseas studying, business, working, and travelling. However, the epidemiological and clinical characteristics of them are still unknown. Methods: We collected data of 46 confirmed COVID-19 patients aged 10 to 35 years from the study hospital. The demographics, epidemiological, and clinical data were collected. Several key epidemiological parameters, the asymptomatic cases and transmission to their family members and the clinical characteristics at admission, and during treatment were summarized. RESULTS: Of 46 confirmed patients, 14 patients (47.3%) were aged from 10 to 24 years, and 24 (52.7%) patients were male. The mean incubation period for symptomatic cases was 6.6 days (95% confidence interval (CI) 4.4 - 9.6). The median serial interval was 1.9 days (95% CI 0.4 - 6.2). Three of asymptomatic cases showed the transmission to their family members. Only 1 patient was identified as severe cases at admission. The common symptoms at admission were dry cough (34, 91.0%), and fever (29, 69.0%). Nearly 60% of the patients had showed ground-glass opacity by chest CT findings. Three patients developed acute kidney injury during treatment. Majority of patients (78.3%) were discharged by the end of the follow-up. Conclusions: The adolescent and young adult patients of COVID-19 had a long incubation period, and a short serial interval. The transmission to their family contactors occurred in asymptomatic cases. Few of the study patients have developed complications during treatment.

Lockdown may partially halt the spread of 2019 novel coronavirus in Hubei province, China (preprint)

We present a timely evaluation of the impact of lockdown on the 2019-nCov epidemic in Hubei province, China. The implementation appears to be effective in reducing about 60% of new infections and deaths, and its effect also appears to be sustainable even after its removal. Delaying its implementation reduces its effectiveness. However, the direct economic cost of such a lockdown remains to be seen and whether the model is replicable in other Chinese regions remains a matter of further investigation.