Impact of prior SARS-CoV-2 infection on incidence of hospitalization and adverse events following mRNA SARS-CoV-2 vaccination: A nationwide,retrospective cohort study

BackgroundPrevious studies evaluated the SARS-CoV-2 vaccine safety or compared adverse events following vaccination to those from infection. Limited data about the impact of prior infection on post-vaccine adverse events are available. The objective of this study was to evaluate the impact of prior SARS-CoV-2 infection on outcomes shortly after vaccination using a longitudinal design.MethodsNationwide, multicenter, retrospective cohort study of hospitalization, death, and pre-specified adverse event rates among Veterans who received mRNA vaccines within the Veterans Health Administration between 12/11/2020 and 8/31/2021. Daily incidence rates were compared before and after vaccine doses, stratified by history of microbiologically-confirmed SARS-CoV-2.Results3,118,802 patients received a first dose and 2,979,326 a second, including 102,829 with a history of SARS-CoV-2 infection. Daily incident hospitalization rates were unchanged before and after the second dose among patients without previous infection (28.8/100,000 post-dose versus 28.6/100,000 pre-dose, p = 0.92). In previously-infected patients, the hospitalization rate increased above baseline one day following vaccination (158.2/100,000 after dose 2 versus 57.3/100,000 pre-dose, p < 0.001), then returned to baseline. Chart review indicated vaccine side effects, such as fever, constitutional symptoms, weakness, or falls, as the definite (39%) or possible (18%) cause of hospitalization. Affected patients had mean age 75, and 90% had at least one serious comorbidity. Hospitalizations were brief (median 2 days), with rapid return to baseline health. Worse baseline health among previously-infected patients prevented conclusions about mortality risk.ConclusionsTwo-dose mRNA vaccine regimens are safe in a population with many comorbidities. Transient increased risks of hospitalization were identified among patients with prior SARS-CoV-2, absolute risk ～1:1000. Findings support additional study regarding the optimal dosing schedule in this population.FundingNone.     

Safety and immunogenicity of hepatitis E vaccine in elderly people older than 65 years

BackgroundHepatitis E virus (HEV) infection is a leading cause of acute hepatitis worldwide, and results in high morbidity and mortality rates among elderly people in China. The hepatitis E vaccine, Hecolin®, has been shown to be safe and highly efficacious among healthy adults aged 16–65 years old. However, there is no data about Hecolin® vaccination in elderly people older than 65 years (y).MethodsAn open-labeled, controlled trial was conducted to evaluate the safety and immunogenicity of Hecolin® among the elderly aged >65 y. A total of 601 eligible participants were enrolled. Among them, 200 elderly people aged >65 y and 201 adults aged 18–65 y were assigned to the Hecolin® groups and vaccinated at day 0, month 1 and month 6. Serum samples were collected for anti-HEV IgG determination at day 0 prior to immunization and at month 7. The remaining 200 elderly people aged >65 y were assigned to the safety control group and received no intervention but were instructed to report any adverse events that occurred during the whole study period in the same way as those in the Hecolin® groups.ResultsAfter receiving 3 doses of Hecolin® with the standard schedule, most (96.7%) of the vaccinated elderly people aged >65 y seroconverted at one month after the final dose (month 7). At month 7, the geometric mean concentrations of anti-HEV IgG were 5.36 (95% CI, 3.88–7.41) and 19.65 (95% CI, 16.81–22.98) among the baseline seronegative and seropositive elderly, respectively. Of the vaccinated elderly, 97.3% (177/182) had anti-HEV IgG levels higher than 1.0 WU/ml at month 7. Hecolin® was very well tolerated in this population. No vaccine-related SAEs were reported.ConclusionsHecolin® is immunogenic and well tolerated in elderly people aged greater than 65 years.     

Estimation of mid-and long-term benefits and hypothetical risk of Guillain-Barre syndrome after human papillomavirus vaccination among boys in France: A simulation study

BackgroundThe burden of human papillomavirus (HPV) infection can be substantially reduced through vaccination of girls, and gender-neutral policies are being adopted in many countries to accelerate disease control among women and expand direct benefits to men. Clinical direct benefit of boys HPV vaccination has been established for ano-genital warts and anal cancer. HPV vaccines are considered safe, but an association with Guillain-Barre syndrome has been found in French reimbursement and hospital discharge data.MethodsWe conducted a Monte-Carlo simulation assuming a stable French population of 11- to 14-year-old boys, adult men and men having sex with men. We modelled and quantified the mid-term benefits as the annually prevented ano-genital warts among the 8.72 M men aged 15–35 years and the long-term benefits as the annually prevented anal cancer cases among the 17.4 M men aged 25–65 years. We also estimated the number of Guillain-Barre syndrome cases hypothetically induced by vaccination.ResultsWith a vaccine coverage of 30%, an annual number of 9310 (95% uncertainty interval [7050–11,200]) first ano-genital warts episodes among the 8.72 M men aged 15–35 years are prevented. According to more or less optimistic hypotheses on the proportion of HPV cancers covered by the vaccine, between 15.1 [11.7–17.7] and 19.2 [15.0–22.6] cases of anal cancer among the 17.4 M men aged 25–65 years would be annually avoided. Among men having sex with men, the corresponding figures were 1907 (1944–2291) for ano-genital warts and between 2.0 [0.23–4.5] and 2.6 [0.29–5.7] for anal cancer. Among 11- to 14-year-old boys, 0.82 (0.15–2.3) Guillain-Barre syndrome cases would be induced annually.InterpretationA long-term program of HPV vaccination among boys in France would avoid substantially more cancer cases than hypothetically induce Guillain-Barre syndrome cases, in the general and specifically the homosexual population. Additional benefits may arise with the possible vaccine protection against oro-laryngeal and –pharyngeal cancer.     

COVID-19 vaccination attitudes,values and intentions among United States adults prior to emergency use authorization

IntroductionSafe and effective vaccines against Coronavirus Disease 2019 (COVID-19) provide the best opportunity to control the pandemic. Having safe and efficacious vaccines available is only half the equation; people must also take them. We describe a study to identify COVID-19 vaccine attitudes, values and intentions immediately preceding authorization of COVID-19 vaccines in the US.MethodsA national panel survey was conducted to measure intent to receive COVID-19 vaccines as well as disease and vaccine attitudes, values and trust in local, state and federal public health authorities.ResultsGreater than 80% of respondents reported confidence they could adhere to COVID recommendations such as mask wearing, social distancing and hand washing. The majority of respondents (70%) reported believing that current drugs were somewhat or very good at treating COVID-19 infection.Vaccine intent fell into three groups: Intenders (50%), Wait and Learn (40%), and Unlikelys (10%). Intent to get vaccinated was substantially lower among African American (32%), and higher among men (56%), those over 60 years of age (61%), those with a Bachelor’s degree or higher (63%), and Democrats (63%). The Wait and Learn group, compared to the Intenders, were less likely to report being diagnosed with a high risk condition for COVID-19, receiving an influenza vaccine in the past 12 months, discussing COVID-19 vaccine with their healthcare provider, perceiving COVID-19 as severe, considering a COVID-19 vaccine important to stop the spread of infection, and wering a mask usually or almost always.ConclusionOnly half of US adults intend to accept COVID-19 vaccines; most others (40%) are uncertain. Levels of immunity associated with community protection will not be achieved without reaching those who are currently uncertain. Characterizing COVID-19 vaccine attitudes and intentions and ascertaining values and trust in local, state, and federal public health authorities that impact vaccine decision-making are essential.     

Immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2 with 12-dose vials: An interim analysis

BackgroundChAdOx1 nCoV-19 (AZD 1222) is the main vaccine planned for general administration in Thailand. This vaccine is stored in multiple-dose vials meant to be administered to 10 recipients with a volume of 0.5 mL for each dose. However, the vaccine vials were overfilled, which allows the administration of more than 10 doses per vial. We have stipulated the preparation and use of ChAdOx1 nCoV-19 vaccine using traditional 21 or 25G needles and planned to investigate the immune responses of participants who were administered the ChAdOx1 nCoV-19 vaccine using this technique.MethodsWe measured anti-SARS-CoV-2 anti-spike RBD IgG and neutralising antibody using a surrogate virus neutralising test (sVNT) among adults aged 18–72 years on average of 8.57 weeks (IQR 6.85–8.93) after the first dose of ChAdOx1 nCoV-19 vaccine. The primary outcome was the antibody level. The secondary outcomes included adverse events, factors affecting antibody levels, and incidence of COVID-19 infection.FindingsIn all, 60 participants comprised 25 males and 35 females. The mean age was 53.70 ± 17.48 years. BMI was 23.45 ± 3.69 kg/m². Tests for the neutralising antibody were positive in 60% of the participants (71.4% among males and 44% among females). The median anti-SARS-CoV-2 QuantiVac (anti-spike IgG) level among male and female samples was 111.83 BAU/mL (IQR 73.48–196.74 BAU/mL) and 159.65 BAU/mL (IQR 100.39–371.81), respectively. The positive QuantiVac value of male and female samples was 88.00% and 98.44%, respectively (p-value = 0.382) .A good correlation was observed between neutralising Ab and anti-spike RBD IgG.ConclusionPatients receiving 12-dose per vial injections of ChAdOx1 nCoV-19 exhibited high levels of immunity without severe side effects. This technique can be adopted to maximise the number of doses per vial while preserving vaccine effectiveness.     

The potential effects of deploying SARS-Cov-2 vaccines on cold storage capacity and immunization workload in countries of the WHO African Region

BackgroundSARS-CoV-2 vaccines will be deployed to countries with limited immunization systems.MethodsWe assessed the effect of deploying SARS-Cov-2 vaccines on cold storage capacity and immunization workload in a simulated WHO African Region country using region-specific data on immunization, population, healthcare workers (HCWs), cold storage capacity (quartile values for national and subnational levels), and characteristics of an approved SARS-CoV-2 vaccine. We calculated monthly increases in vaccine doses, doses per vaccinator, and cold storage volumes for four-month SARS-CoV-2 vaccination campaigns targeting risk groups compared to routine immunization baselines.ResultsAdministering SARS-CoV-2 vaccines to risk groups would increase total monthly doses by 27.0% for ≥ 65 years, 91.7% for chronic diseases patients, and 1.1% for HCWs. Assuming median nurse density estimates adjusted for absenteeism and proportion providing immunization services, SARS-CoV-2 vaccination campaigns would increase total monthly doses per vaccinator by 29.3% for ≥ 65 years, 99.6% for chronic diseases patients, and 1.2% for HCWs. When we applied quartiles of actual African Region country vaccine storage capacity, routine immunization vaccine volumes exceeded national-level storage capacity for at least 75% of countries, but subnational levels had sufficient storage capacity for SARS-CoV-2 vaccines for at least 75% of countries.ConclusionsIn the WHO African Region, SARS-CoV-2 vaccination campaigns would substantially increase doses per vaccinator and cold storage capacity requirements over routine immunization baselines. Pandemic vaccination campaigns would increase storage requirements of national-level stores already at their limits, but sufficient capacity exists at subnational levels. Immediate attention to strengthening immunization systems is essential to support pandemic responses.     

Uncovering inequities in Covid-19 vaccine coverage for adults and elderly in Brazil: A multilevel study of 2021–2022 data

Vaccination is crucial for reducing severe COVID-19 cases, hospitalizations, and deaths. However, vaccine access disparities within countries, particularly in low- and middle-income nations, may leave disadvantaged regions and populations behind. This study aimed to investigate potential inequalities in vaccine coverage among Brazilian aged 18 years and older based on demographic, geographic, and socioeconomic characteristics at the municipal level. A total of 389 million vaccination records from the National Immunization Program Information System were analyzed to calculate vaccine coverage rates for the first, second, and booster doses among adults (18–59 years) and elderly (60 + years) vaccinated between January 2021 and December 2022. We analyzed the data by gender and used a three-level (municipalities, states, regions) multilevel regression analysis to assess the association between vaccine coverage and municipal characteristics. Vaccination coverage was higher among the elderly than among adults, particularly for the second and booster doses. Adult women showed higher coverage rates than men (ranging from 118 % to 25 % higher along the analyzed period). Significant inequalities were observed when analyzing the evolution of vaccination coverage by sociodemographic characteristics of municipalities. In the early stages of the vaccination campaign, municipalities with higher per capita Gross Domestic Product (pGDP), educational level, and fewer Black residents reached higher population coverages earlier. In December 2022, adult and elderly booster vaccine coverage was 43 % and 19 %, respectively, higher in municipalities in the highest quintile of educational level. Higher vaccine uptake was also observed in municipalities with fewer Black residents and higher pGDP. Municipalities accounted for most of the variance in vaccine coverage (59.7 %-90.4 % depending on the dose and age group). This study emphasizes the inadequate booster coverage and the presence of socioeconomic and demographic disparities in COVID-19 vaccination rates. These issues must be addressed through equitable interventions to avoid potential disparities in morbidity and mortality.     

Evaluation of mortality risk after COVID-19 vaccination,Utah 2021

IntroductionIn order to evaluate trends in death after COVID-19 vaccination we analyzed the timing of death relative to vaccination date and the causes of death in vaccinated Utahns in 2021.MethodsWe matched people in the Utah immunization registry with documented COVID-19 vaccinations between December 18, 2020 and December 31, 2021 to Utah’s 2021 vital statistics death records. Vaccinated people were categorized as having one, two, or ≥ three COVID-19 vaccine doses in a time-updated metric. We examined crude mortality rates by dosing groups in two-week intervals for all deaths, and by COVID-19 versus non-COVID-19 causes, within the 44 weeks following receipt of the most recent vaccine.ResultsWe identified 2,072,908 individuals who received at least one dose of COVID-19 vaccine of whom 10,997 died in 2021. Only 17.5 % of the total vaccinated population was age 65+, while 80.9 % of those who died were over 65. In the four weeks following the first or second vaccination, all-cause mortality was low and then stabilized for the remainder of the evaluation period at a bi-weekly average of 33.0 and 39.0 deaths/100,000 people for one and two doses, respectively. Typical seasonal variation in death was observed among those with two doses. Small sample size precluded analysis of those with ≥ three doses, but trends were similar.ConclusionsMortality rates in the 44 weeks following the COVID-19 vaccination did not show trends suggesting an increase in mortality related to COVID-19 vaccination, reinforcing the safety of COVID-19 vaccines. This represents an accessible approach for local evaluation.     

Willingness to get vaccinated against Covid-19 and attitudes toward vaccination in general

BackgroundHigh uptake of Covid-19 vaccination is required to reach herd immunity.MethodsA representative sample of 2,060 Belgians were surveyed in October 2020. Regression analyses identified the predictors associated with willingness to get vaccinated against Covid-19, and attitudes toward vaccination in general.Results34% of the participants reported that they will definitely get vaccinated against Covid-19 and 39% that they would “probably”. Intended uptake was strongly associated with age, opinion on the government’s dealing with the Covid-19 pandemic, medical risk, spoken language, gender, and to a lesser extent with having known someone who was hospitalised because of Covid-19. Similar predictors were identified for attitudes to vaccination in general. Covid-19 vaccine hesitancy was more marked in age groups below 54 years old. We further analysed a sample of 17% (N = 349) found favourable to vaccination in general but not willing to be vaccinated against Covid-19. They were mainly female, young, French speaking, slightly less educated, working, and did not belong to a Covid-19 risk group. They were very dissatisfied with the government’s dealing with the pandemic, and did not know someone who was hospitalised because of Covid-19.ConclusionsVaccine hesitancy was higher for Covid-19 vaccines than for other vaccines. The part of the population being convinced of the utility of vaccination in general but hesitant about the Covid-19 vaccine is a primary interest group for tailored communication campaigns in order to reach the vaccine coverage needed for herd immunity.     

International estimates of intended uptake and refusal of COVID-19 vaccines: A rapid systematic review and meta-analysis of large nationally representative samples

BackgroundWidespread uptake of COVID-19 vaccines will be essential to controlling the COVID-19 pandemic. Vaccines have been developed in unprecedented time and quantifying levels of hesitancy towards vaccination among the general population is of importance.MethodsSystematic review and meta-analysis of studies using large nationally representative samples (n ≥ 1000) to examine the percentage of the population intending to vaccinate, unsure, or intending to refuse a COVID-19 vaccine when available. Generic inverse meta-analysis and meta-regression were used to pool estimates and examine time trends. PubMed, Scopus and pre-printer servers were searched from January-November 2020. Registered on PROSPERO (CRD42020223132).FindingsTwenty-eight nationally representative samples (n = 58,656) from 13 countries indicate that as the pandemic has progressed, the percentage of people intending to vaccinate decreased and the percentage of people intending to refuse vaccination increased. Pooled data from surveys conducted during June-October suggest that 60% (95% CI: 49% to 69%) intend to vaccinate and 20% (95% CI: 13% to 29%) intend to refuse vaccination, although intentions vary substantially between samples and countries (I² > 90%). Being female, younger, of lower income or education level and belonging to an ethnic minority group were consistently associated with being less likely to intend to vaccinate. Findings were consistent across higher vs. lower quality studies.InterpretationIntentions to be vaccinated when a COVID-19 vaccine becomes available have been declining across countries and there is an urgent need to address social inequalities in vaccine hesitancy and promote widespread uptake of vaccines as they become available.FundingN/A.     

Assessing the cost-effectiveness of COVID-19 vaccines in a low incidence and low mortality setting: the case of Thailand at start of the pandemic

Objective

This study aimed to assess the cost-effectiveness of COVID-19 vaccines, preferred COVID-19 vaccine profiles, and the preferred vaccination strategies in Thailand.

Methods

An age-structured transmission dynamic model was developed based on key local data to evaluate economic consequences, including cost and health outcome in terms of life-years (LYs) saved. We considered COVID-19 vaccines with different profiles and different vaccination strategies such as vaccinating elderly age groups (over 65s) or high-incidence groups, i.e. adults between 20 and 39 years old who have contributed to more than 60% of total COVID-19 cases in the country thus far. Analyses employed a societal perspective in a 1-year time horizon using a cost-effectiveness threshold of 160,000 THB per LY saved. Deterministic and probabilistic sensitivity analyses were performed to identify and characterize uncertainty in the model.

Results

COVID-19 vaccines that block infection combined with social distancing were cost-saving regardless of the target population compared to social distancing alone (with no vaccination). For vaccines that block infection, the preferred (cost-effective) strategy was to vaccinate the high incidence group. Meanwhile, COVID-19 vaccines that reduces severity (including hospitalization and mortality) were cost-effective when the elderly were vaccinated, while vaccinating the high-incidence group was not cost-effective with this vaccine type. Regardless of vaccine type, higher vaccination coverage, higher efficacy, and longer protection duration were always preferred. More so, vaccination with social distancing measures was always preferred to strategies without social distancing. Quarantine-related costs were a major cost component affecting the cost-effectiveness of COVID-19 vaccines.

Conclusion

COVID-19 vaccines are good value for money even in a relatively low-incidence and low-mortality setting such as Thailand, if the appropriate groups are vaccinated. The preferred vaccination strategies depend on the type of vaccine efficacy. Social distancing measures should accompany a vaccination strategy.

     

Effect of COVID-19 vaccination on mortality by COVID-19 and on mortality by other causes,the Netherlands,January 2021–January 2022

BackgroundWe aimed to estimate vaccine effectiveness (VE) against COVID-19 mortality, and to explore whether an increased risk of non-COVID-19 mortality exists in the weeks following a COVID-19 vaccine dose.MethodsNational registries of causes of death, COVID-19 vaccination, specialized health care and long-term care reimbursements were linked by a unique person identifier using data from 1 January 2021 to 31 January 2022. We used Cox regression with calendar time as underlying time scale to, firstly, estimate VE against COVID-19 mortality after primary and first booster vaccination, per month since vaccination and, secondly, estimate risk of non-COVID-19 mortality in the 5 or 8 weeks following a first, second or first booster dose, adjusting for birth year, sex, medical risk group and country of origin.ResultsVE against COVID-19 mortality was > 90 % for all age groups two months after completion of the primary series. VE gradually decreased thereafter, to around 80 % at 7–8 months post-primary series for most groups, and around 60 % for elderly receiving a high level of long-term care and for people aged 90+ years. Following a first booster dose, the VE increased to > 85 % in all groups. The risk of non-COVID-19 mortality was lower or similar in the 5 or 8 weeks following a first dose compared to no vaccination, as well as following a second dose compared to one dose and a booster compared to two doses, for all age and long-term care groups.ConclusionAt the population level, COVID-19 vaccination greatly reduced the risk of COVID-19 mortality and no increased risk of death from other causes was observed.     

Willingness of Brazilian caregivers in having their children and adolescents vaccinated against Covid-19

BackgroundThe vaccination of children and adolescents for the prevention of Covid-19 is important to:decrease in deaths and hospitalizations, prevent multisystem inflammatory syndrome, avoid long-term complications and decrease the suspension of on-site classes. Despite of these benefits, some studies have shown that some caregivers are still hesitancy.MethodsThis is a voluntary and anonymous online survey conducted from November 17 to December 14, 2021, in Brazil, through a free-of-charge platform with a link provided on social networks. A bivariate analysis was conducted with the independent variables, with vaccine hesitancy as the outcome variable, and a multivariate logistic model was used to calculated adjusted odds ratios.ResultsThe sample included 15,297 respondents. Approximately 13.3 % (2,028) of the caregivers were hesitant to vaccinate their children and adolescents against Covid-19 in at least one age group. The vaccination hesitanty rate of caregivers of children aged 0–4 years, 5–11 years and adolescents were 16 %, 13 %, 15 %, respectively. The principal factors associated with vaccine hesitancy were the following: belief that they need to wait longer, belief that children that had natural infection doesn’t need to vaccinate and belief that vaccine has long term adverse effects.Interpretation.The present study showed that the willingness of caregivers to have their children and adolescents vaccinated in Brazil is high compared to data from adult and pediatric international studies. This study provides a profile of the hesitant caregivers considering their perspectives and beliefs regarding vaccines that can help the elaboration of strategies to increase vaccine adherence.     

Side effects during the week after first dose vaccination with four Covid-19 vaccines. Results of the ProVaVac Survey Study with 13,837 people in Spain

BackgroundIn 2021, four vaccines against Covid-19 (BNT162b2, mRNA-1273, ChAdOx1nCoV-19, and JNJ-78436735) were employed in the region of Valencia, Spain. We conducted a survey to identify real-world, self-reported frequency and severity of side effects during the week after vaccination.MethodsSurvey data was obtained from April 19, 2021, to October 6, 2021, at three different moments in time: day one, day three and day seven after vaccination. Answers were linked to individual-level, personal and clinical information. Respondents were stratified by the vaccine they received and reported effects were presented over time and stratified by severity. We compared our results per vaccine with the frequencies stated in each Summary of Product Characteristics (SmPC). We used binomial logistic models to identify associations between respondent characteristics and side effects.ResultsNo symptoms were reported by 1,986 respondents (14.35 %), 6,254 informed exclusively mild symptoms (45.20 %), 3,444 up to moderate symptoms (24.89 %), and 2,153 people (15.56 %) notified also severe symptoms. Among the latter, the more frequent were extreme tiredness (7.0 %), and nausea or vomiting (7.1 %). The reported frequency of facial paralysis (0.4 %) was much higher than reflected in SmPCs. Female sex, younger age, previous positive Active Infection Diagnostic Test, chronicity, and vaccination with other than the BNT162b2 vaccine were associated to an increased risk of side effects (p < 0.001).ConclusionsSide effects after vaccination are common in the real-world. However, they are principally mild, and their frequency declines after a few days. Providing patients with dependable, beforehand information about side effects may improve outcomes and reinforce vaccination programs.     

Predictors of COVID-19 vaccine uptake among people who inject drugs

IntroductionWe studied characteristics of COVID-19 vaccination uptake among people who inject drugs (PWID).MethodsParticipants aged ≥18 years who injected drugs ≤1 month ago were recruited into a community-based cohort from October 2020 to September 2021 in San Diego, California Poisson regression identified correlates of having had ≥1 COVID-19 vaccine dose based on semi-annual follow-up interviews through March 15, 2022.ResultsOf 360 participants, 74.7% were male, mean age was 42 years; 63.1% were Hispanic/Mexican/Latinx. More than one-third had ≥1 co-morbidity. HIV and HCV seroprevalence were 4.2% and 50.6% respectively; 41.1% lacked health insurance. Only 37.8% reported having ≥1 COVID-19 vaccine dose. None received ≥3 doses. However, of those vaccinated, 37.5% were previously unwilling/unsure about COVID-19 vaccines. Believing COVID-19 vaccines include tracking devices (adjusted incidence rate ratio [aIRR]: 0.62; 95% CI: 0.42,0.92) and lacking health insurance (aIRR: 0.60; 95% CI: 0.40,0.91) were associated with approximately 40% lower COVID-19 vaccination rates). Ever receiving influenza vaccines (aIRR: 2.16; 95%CI: 1.46, 3.20) and testing HIV-seropositive (aIRR: 2.51; 95% CI: 1.03, 6.10) or SARS-CoV-2 RNA-positive (aIRR: 1.82; 95% CI: 1.05, 3.16) independently predicted higher COVID-19 vaccination rates. Older age, knowing more vaccinated people, and recent incarceration were also independently associated with higher COVID-19 vaccination rates.ConclusionsOne year after COVID-19 vaccines became available to U.S. adults, only one third of PWID had received ≥1 COVID-19 vaccine dose. Multi-faceted approaches that dispel disinformation, integrate public health and social services and increase access to free, community-based COVID-19 vaccines are urgently needed.     

Cost-effectiveness of quadrivalent versus trivalent influenza vaccine for elderly population in China

BackgroundInfluenza-associated excess death occurred most in the elderly. We aimed to assess the cost-effectiveness of quadrivalent influenza vaccine (QIV) versus trivalent influenza vaccine (TIV) for prevention of influenza infection among elderly population in China.MethodsA decision-analytic model was developed to compare 1-year clinical and economic outcomes of three influenza vaccination options (no vaccination, TIV, and QIV) in a hypothetical cohort of Chinese elderly aged 69 years. Outcome measures included cost, influenza infection rate, influenza-related mortality rate, quality-adjusted life-years (QALY) loss, and incremental cost-effectiveness ratio (ICER) from societal perspective. Sensitivity analyses were performed to examine the uncertainty of model inputs.ResultsBase-case results showed no vaccination was dominated (more costly at higher QALY loss) by TIV and QIV. QIV was more costly (USD56.29 versus USD54.28) with lower influenza infection rate (0.608 versus 0.623), mortality rate (0.00199 versus 0.00204), and QALY loss (0.01213 versus 0.01243) than TIV. QIV was cost-effective compared to TIV with ICER of 6,700 USD/QALY below the willingness-to-pay threshold (29,580 USD/QALY). One-way sensitivity analysis found the cost-effectiveness of QIV was subject to the relative risk of vaccine effectiveness of QIV versus TIV, and TIV would be cost-effective if the relative risk was below 1.05. In 10,000 Monte Carlo simulations, the probabilities of QIV, TIV, and no vaccination to be cost-effective were 86.3%, 13.7%, and 0%, respectively.ConclusionQIV appears to be a cost-effective option compared to TIV and no influenza vaccination for elderly population in China.     

Vaccine preferences and acceptance of older adults

BackgroundExpanding vaccination programs for the older population might be important as older adults are becoming a larger proportion of the general population. The aim of this study is to determine the relative importance of vaccine and disease specific characteristics and acceptance for Dutch older adults, including pneumococcal disease, herpes zoster, pertussis vaccination, and influenza vaccination.MethodsA discrete choice experiment was conducted to generate choice data that was analyzed using a mixed multinomial logit statistical model.ResultsImportant factors that were associated with vaccination acceptance in older adults are high mortality risk of the infectious disease, high susceptibility of getting the infectious disease, and high vaccine effectiveness. Age, influenza vaccination in 2013 and self-perceived health score were identified as personal factors that affect vaccine preference. Potential vaccination rates of older adults were estimated at 68.1% for pneumococcal vaccination, 58.1% for herpes zoster vaccination, 53.9% for pertussis vaccination and 54.3% for influenza vaccination. For persons aged 50–65, potential vaccination rates were estimated at 58.1% for pneumococcal vaccination, 49.5% for herpes zoster vaccination, 43.9% for pertussis vaccination and 42.2% for influenza vaccination. For persons aged 65 and older, these were respectively 76.2%, 67.5%, 57.5% and 65.5%.DiscussionOur results suggest that older adults are most likely to accept pneumococcal vaccination of the four vaccines. Information provision accompanied with the implementation of a new vaccine has to be tailored for the individual and the vaccine it concerns. Special attention is needed to ensure high uptake among persons aged 50–65 years.     

Cost-effectiveness of a 3-antigen versus single-antigen vaccine for the prevention of hepatitis B in adults in the United States

ObjectivesThe first 3-antigen hepatitis B vaccine was approved by the United States (US) Food and Drug Administration in November 2021 and was recommended by the Centers for Disease Control and Prevention in 2022. We estimated the cost-effectiveness of this 3-antigen vaccine (PreHevbrio™) relative to the single-antigen vaccine, Engerix-B^TM, to prevent hepatitis B virus (HBV) infection among US adults.MethodsA cost-effectiveness model was developed using a combined decision-tree and Markov structure to follow 100,000 adults over their remaining lifetimes after vaccination with either the 3-antigen or single-antigen vaccine. Outcomes from societal and healthcare sector perspectives were calculated for adults aged 18–44, 45–64, and ≥65 years; adults with diabetes; and adults with obesity. Seroprotection rates were obtained from the phase 3, head-to-head PROTECT trial (NCT03393754). Incidence, vaccine costs, vaccine adherence rates, direct and indirect costs, utilities, transition probabilities, and mortality were obtained from published sources. Health outcomes and costs (2020 USD) were discounted 3% annually and reported by vaccine and population. One-way sensitivity and scenario analyses were conducted.ResultsIn the model, the 3-antigen vaccine led to fewer HBV infections, complications, and deaths compared with the single-antigen vaccine in all modeled populations due to higher rates and faster onset of seroprotection. Compared with the single-antigen vaccine, the 3-antigen vaccine had better health outcomes, more quality-adjusted life-years (QALYs), and lower costs in adults aged 18–64 years, adults with diabetes, and adults with obesity (dominant strategy). For adults aged ≥65 years, the 3-antigen vaccine was cost-effective compared with the single-antigen vaccine ($26,237/QALY gained) below common willingness-to-pay thresholds ($50,000-$100,000/QALY gained). In sensitivity analyses, results were sensitive to vaccine cost per dose, incidence, and age at vaccination.ConclusionThe recently approved 3-antigen vaccine is a cost-saving or cost-effective intervention for preventing HBV infection and addressing the long-standing burden of hepatitis B among US adults.     

Acute unsolicited adverse events following BNT162b2 vaccine in Saudi Arabia,a real-world data

BackgroundAcute adverse events and anaphylaxis were reported after the administration of coronavirus disease (COVID-19) mRNA vaccines. We aim to explore the nature and outcome of adverse events following BNT162B2 vaccine in a community vaccination center, Riyadh, Saudi Arabia.MethodWithin 30 min post vaccination, all acute adverse events (AAEs) that occurred before March 31st, 2021, and in people older than 16 years were reviewed (AAE group). We used the case definition of Brighton collaboration on vaccine safety to define anaphylaxis. Patients’ demographics, comorbidities, allergy history, and outcome at disposition were collected. Observation duration after vaccination was short (<15 min) or extended (<3 h). Statistical analysis was performed to study AAEs association with the study variables and outcomes.ResultsOut of 71,221 vaccine recipients, 144 (0.002%) had developed 345 AAEs, at a rate of 48.4 events per 10,000 dose administered. The majority of cases in AAE group were first dose recipients (93.8%) and previously healthy (59%), while the minority had a previous history of allergy (6.3%) or a laboratory-confirmed COVID-19 (4.2%). We found a significant association between female gender and the occurrence of any AAE (p-value = 0.002). Per every 10,000 doses administered, non-anaphylactic AAEs were dizziness (17.8), headache (9.7), nausea (7.1), or syncope (3.2). Only one in every ten AAEs was considered serious and resulted in an extended observation (4.8 per 10,000 doses), but only 1/144 required hospitalization for non-anaphylaxis reasons (0.1 per 10,000 doses). According to the Brighton collaboration definition of anaphylaxis, no single case of high certainty anaphylaxis was recorded. No death was documented in this cohort.ConclusionAcute adverse events due to BNT162b2 vaccine were rare and mostly non-serious with a tendency to occur more in women. Further prospective studies on larger vaccine recipients to evaluate the incidence of anaphylaxis in the Saudi population are warranted.