The misunderstanding of vaccine efficacy

Mathematical modeling for estimating influenza vaccine efficacy: A case study of the Valencian Community, Spain

Vaccine efficacy and its quantification is a crucial concept for the proper design of public health vaccination policies. In this work we proposed a mathematical model to estimate the efficacy of the influenza vaccine in a real-word scenario. In particular, our model is a SEIR-type epidemiological model, which distinguishes vaccinated and unvaccinated populations. Mathematically, its dynamics is governed by a nonlinear system of ordinary differential equations, where the non-linearity arises from the effective contacts between susceptible and infected individuals. Two key aspects of this study is that we use a vaccine distribution over time that is based on real data specific to the elderly people in the Valencian Community and the calibration process takes into account that over one influenza season a specific proportion of the population becomes infected with influenza. To consider the effectiveness of the vaccine, the model incorporates a parameter, the vaccine attenuation factor, which is related with the vaccine efficacy against the influenza virus. With this framework, in order to calibrate the model parameters and to obtain an influenza vaccine efficacy estimation, we considered the 2016-2017 influenza season in the Valencian Community, Spain, using the influenza reported cases of vaccinated and unvaccinated. In order to ensure the model identifiability, we choose to deterministically calibrate the parameters for different scenarios and we find the one with the minimum error in order to determine the vaccine efficacy. The calibration results suggest that the influenza vaccine developed for 2016-2017 influenza season has an efficacy of approximately 76.7%, and that the risk of becoming infected is five times higher for an unvaccinated individual in comparison with a vaccinated one. This estimation partially agrees with some previous studies related to the influenza vaccine. This study presents a new integrated mathematical approach to study the influenza vaccine efficacy and gives further insight into this important public health topic.

Vaccinating the Frontlines: A Qualitative Exploration of Hospital Healthcare Worker Perspectives on Influenza and COVID-19 Immunization

Introduction

Although they face higher occupational risk of contracting viral respiratory infections, hospital healthcare worker vaccine hesitancy persists. While most studies have used survey methods to quantify the prevalence of and reasons for healthcare worker vaccine hesitancy, this study employs a qualitative approach to understand their attitudes and beliefs associated with influenza and COVID-19 vaccination.

Methods

To understand frontline healthcare worker experiences and perspectives on influenza and COVID-19 vaccination, 30 semi-structured interviews were conducted in summer/fall 2022 with staff recruited from two Johns Hopkins hospitals in Maryland. An in-depth, key informant interview was conducted with an expert in public health audience engagement. Interviews were audio recorded and transcribed for thematic and Framework analysis using NVivo software (QSR International, Melbourne, Australia).

Results

Healthcare workers engaged in little influenza vaccine information seeking due to their familiarity with the disease and low perceived disease severity. Approximately half (n=16) of healthcare workers reported no vaccine hesitancy towards influenza or COVID-19 vaccines. No physicians or physician assistants expressed any vaccine hesitancy, while most nurses expressed some (n=10). More than half of the women (n=14) expressed COVID-19 vaccine hesitancy compared to none of the men. Structural factors including hospital tier, unit assignment, and professional role influenced perceived risk of disease exposure and subsequent healthcare worker vaccination decisions. Institutional policies, including mandates and a pro-vaccine environment encouraged vaccination uptake. Healthcare workers reported being more receptive to vaccine messaging that focused on protection from disease, scientific and public health data and their heightened occupational exposure to pathogens.

Conclusions

Despite their medical knowledge, healthcare workers are susceptible to vaccine hesitancy. Strategies to address specific concerns are needed and can be informed by our findings. A flexible and multi-pronged approach that considers individual anxieties, workplace structures, and the need for open communication with tailored messaging is necessary to promote vaccine acceptance in healthcare settings.

KEY MESSAGES

What is already known on this topic: Healthcare worker vaccine hesitancy has been associated with many factors including race, gender, age and concerns about vaccine safety.What this study adds: Much of the research on healthcare worker vaccine hesitancy has used surveys and questionnaires giving a broad description of the prevalence and patterns of vaccine hesitancy in the healthcare workforce. This qualitative study examines vaccine behavior (rather than merely intent) through a cross comparison of healthcare workers' experiences and attitudes towards influenza and COVID-19 vaccination.How this study might affect research, practice or policy: Study findings can be used to help tailor vaccine messaging to hospital healthcare workers which could offset concerns regarding vaccine efficacy and risk, to promote vaccine uptake.

Framing COVID-19 Preprint Research as Uncertain: A Mixed-Method Study of Public Reactions

During the COVID-19 pandemic, journalists were encouraged to convey uncertainty surrounding preliminary scientific evidence, including mentioning when research is unpublished or unverified by peer review. To understand how public audiences interpret this information, we conducted a mixed method study with U.S. adults. Participants read a news article about preprint COVID-19 vaccine research in early April 2021, just as the vaccine was becoming widely available to the U.S. public. We modified the article to test two ways of conveying uncertainty (hedging of scientific claims and mention of preprint status) in a 2 × 2 between-participants factorial design. To complement this, we collected open-ended data to assess participants' understanding of the concept of a scientific preprint. In all, participants who read hedged (vs. unhedged) versions of the article reported less favorable vaccine attitudes and intentions and found the scientists and news reporting less trustworthy. These effects were moderated by participants' epistemic beliefs and their preference for information about scientific uncertainty. However, there was no impact of describing the study as a preprint, and participants' qualitative responses indicated a limited understanding of the concept. We discuss implications of these findings for communicating initial scientific evidence to the public and we outline important next steps for research and theory-building.

Unbalanced global vaccine product trade pattern: A network perspective

Mass vaccination is the most cost-effective intervention in response to public health events. Thus, equitable access to vaccine products is essential to ensure global human health. Based on the global vaccine product trade data from 2000 to 2018 and employing social network analysis, this paper explores the unbalanced pattern of global vaccine product trade and assesses the sensitivity interdependence between countries. Overall, the analysis shows that global vaccine product trade links have long been highly concentrated within developed countries in Europe and America. Nevertheless, with the rise of global and regional hub countries, the global vaccine product trade network has begun to evolve from a unipolar structure with the U.S. as the sole core to a multipolar structure with the U.S. and Western European countries as the core. Meanwhile, emerging countries, represented by China and India, are increasingly participating in the global vaccine product trade network and are beginning to play an important role. The formation of this multipolar pattern has provided countries in the Global South with more options for cooperation in the vaccine product trade and reduces the sensitivity interdependence of network periphery countries on core countries, which consequently reduces the global supply risk of vaccine products.

Nudging COVID-19 Vaccine Uptake by Changing the Default: A Randomized Controlled Trial

BACKGROUND

Although vaccination against SARS-CoV-2 is considered the central strategy against the pandemic, uptake lags behind target rates.

METHOD

To explore whether this rate could be enhanced by a nudging strategy that exploits the status quo bias, we conducted a randomized controlled trial in northern Italy comparing vaccination acceptance among 2000 adults, ages 50 to 59 years, who were either invited to set an appointment (opt-in group) or assigned an individual appointment (opt-out group).

RESULTS

Results indicate a difference of 3.2 percentage points, which represents a 32% relative increase in the vaccination rate for the opt-out group compared with the opt-in group.

CONCLUSIONS

A significant portion of those who remain unvaccinated may not hold strong beliefs against vaccination but rather tend to inaction and may therefore be nudged toward vaccination with a reduction of action required.

HIGHLIGHTS

Reluctant adults (50-59 years), who had not yet received vaccines against COVID-19, were sent letters announcing appointment availabilityIn an RCT, the status quo option in the notices influenced the rate of vaccine acceptanceNudging via pre-scheduled appointments encouraged vaccine uptake more than invitations to schedule didSwitching the default option yielded a 32% relative increase (13.1% vs. 9.9%) in vaccination.

The COVID-19 pandemic - what have urologists learned?

On 11 March 2020, the WHO declared the coronavirus disease 2019 (COVID-19) outbreak a pandemic and COVID-19 emerged as one of the biggest challenges in public health and economy in the twenty-first century. The respiratory tract has been the centre of attention, but COVID-19-associated complications affecting the genitourinary tract are reported frequently, raising concerns about possible long-term damage in these organs. The angiotensin-converting enzyme 2 (ACE2) receptor, which has a central role in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) invasion, is highly expressed in the genitourinary tract, indicating that these organs could be at a high risk of cell damage. The detection of SARS-CoV-2 in urine and semen is very rare; however, COVID-19 can manifest through urological symptoms and complications, including acute kidney injury (AKI), which is associated with poor survival, severe structural changes in testes and impairment of spermatogenesis, and hormonal imbalances (mostly secondary hypogonadism). The effect of altered total testosterone levels or androgen deprivation therapy on survival of patients with COVID-19 was intensively debated at the beginning of the pandemic; however, androgen inhibition did not show any effect in preventing or treating COVID-19 in a clinical study. Thus, urologists have a crucial role in detecting and managing damage of the genitourinary tract caused by COVID-19.

Assessment of Attitudes, Main Concerns and Sources of Knowledge Regarding COVID-19 Vaccination in Poland in the Unvaccinated Individuals-A Nationwide Survey

Vaccination is the most effective tool to combat the COVID-19 pandemic. However, it is ineffective without appropriate public acceptance. In Poland, 53% of the country's population is vaccinated, which puts us in the last position among the EU countries. Therefore, this study aims to assess the main concerns regarding vaccination in the unvaccinated population of Poland. The study was based on an original questionnaire that was distributed online. There were three phases of the study: Phase 1-before the preventive vaccination plan, Phase 2-2 months after implementation of the programme, Phase 3-after 4 months when the immunisation rate in Poland was 42%. A total of 4459 individuals participated in the study. As many as 1943 participants were excluded from the analysis due to lack of consent (30 subjects) or COVID-19 vaccination (1913 subjects). Out of the remaining 2516 unvaccinated individuals, 463 were participants in the first phase of the study, 1137 in the second phase of the study, and 916 in the third phase. As the preventive vaccination plan in Poland continued, concerns about vaccine adverse events, safety and efficacy were raised. The only lower concern was that about the vaccine transportation rules. Moreover, as the vaccination programme continued, there was an increase in the percentage of individuals declaring their full reluctance towards vaccination against COVID-19. Conclusions: The Internet is the main source of knowledge about the COVID-19 vaccination, so it should be focused on during vaccination campaigns. The public is primarily concerned about adverse events of vaccines and the lack of appropriate tests of the products used. Therefore, it is advisable to popularise the current state of knowledge and promote reliable information concerning the COVID-19 vaccination.

COVID-19 Vaccine Demand and Financial Incentives

BACKGROUND

Public health experts estimate that only very high COVID-19 vaccine uptake levels can result in herd immunity.

OBJECTIVE

This study's main objective was to evaluate the impact of vaccine price levels, including payments, and the efficacy levels on COVID-19 vaccine demand.

METHODS

Data for this study were collected from an online survey of 2000 US individuals aged 18 years and older, which included a set of contingent valuation questions. Parametric and nonparametric procedures were used to estimate the distribution of willingness-to-pay and willingness-to-accept values for the vaccine and to assess its association with vaccine efficacy levels (50, 70, and 95%).

RESULTS

Most of the individuals (60%) indicated they were willing to pay a positive amount for the vaccine; 13.7% said they would only accept the vaccine if it were free; 14.1% were willing to take the vaccine only if they were paid; and 12.2% were not willing to accept the vaccine. The vaccine efficacy level was found to affect an individual's demand for the vaccine. Estimated mean willingness-to-pay values were: US$594, US$706, and US$723 for vaccines with efficacy levels of 50, 70, and 95%, respectively.

CONCLUSIONS

US individuals highly value the COVID-19 vaccine, and about 88% of the US population would accept the vaccination; however, 14% indicated they would get vaccinated if compensated. Payments of about US$500 or more would be needed to sufficiently incentivize 50% or more of this group vaccinated.

Changes in Attitudes and Beliefs Concerning Vaccination and Influenza Vaccines between the First and Second COVID-19 Pandemic Waves: A Longitudinal Study

Perceptions of the risks of vaccine-preventable diseases and preventive behaviors change over time. The ongoing COVID-19 pandemic may have modified laypeople's attitudes towards routine vaccinations. In this longitudinal study, we aimed to assess changes in attitudes and beliefs concerning (influenza) vaccines between the first and second COVID-19 pandemic waves. A total of 1979 participants completed both 2020 and 2021 surveys. After one year, more interviewees agreed that vaccines were fundamental and should be mandatory (77.3% vs. 75.0%). Analogously, willingness to undergo influenza vaccination increased (p < 0.001) from 44.1% to 48.6%. This increase was seen in subjects aged ≥35 years. Previous influenza vaccinations, receipt of a COVID-19 vaccine, positive attitudes towards (influenza) vaccination, male sex, and older age were the main correlates of willingness to receive the 2021/22 influenza vaccine. Totals of 12.6% and 11.8% had no intention to receive the next seasonal influenza and COVID-19 vaccines, respectively. Most respondents favored a hypothetical combined influenza/COVID-19 vaccine (73.7%) or influenza and COVID-19 vaccine co-administration (67.5%). In Italy, influenza and COVID-19 vaccination hesitancy and refusal are common. Effective public health strategies to pursue higher uptake of both vaccines are urgently needed.