Increased Risk of Thyroid Eye Disease Following Covid-19 Vaccination

CONTEXT

SARS-CoV-2 infection and Covid-19 vaccines have been associated with thyroid disorders.

OBJECTIVE

We analyzed the risk of thyroid eye disease (TED) following Covid-19 vaccination. This was a self-controlled case series study at a tertiary referral center for TED. A total of 98 consecutive patients with newly developed (n = 92) or reactivated (n = 6) TED occurring between January 1, 2021, and August 31, 2022, were included. TED was assessed in patients undergoing Covid-19 vaccination. Person-days were defined as exposed if TED occurred 1 to 28 days after vaccination, and unexposed if occurring outside this time window. Conditional Poisson regression models were fitted to calculate incidence rate ratio (IRR) and 95% CI of exposed vs unexposed. Sensitivity analyses were conducted considering different exposed periods, and effect modification by potential TED risk factors.

RESULTS

Covid-19 vaccines were administered in 81 people, 25 (31%) of whom developed TED in exposed and 56 (69%) in unexposed periods. The IRR for TED was 3.24 (95% CI 2.01-5.20) and 4.70 (95% CI 2.39-9.23) in patients below 50 years of age. Sex, smoking, and radioiodine treatment did not modify the association between TED and vaccination. TED risk was unrelated to the number of vaccine doses, and progressively decreased over time following vaccination (P trend = .03).

CONCLUSION

The risk of TED was significantly increased after Covid-19 vaccination, especially in people below 50 years of age. Possible mechanisms include spike protein interaction with the angiotensin-converting enzyme II receptor, cross-reactivity with thyroid self-proteins, and immune reactions induced by adjuvants. We suggest monitoring of individuals undergoing Covid-19 vaccination, especially if young and at risk for autoimmunity.

Covid-19 Vaccine Hesitancy and Under-Vaccination among Marginalized Populations in the United States and Canada: A Scoping Review

BACKGROUND

Amid persistent disparities in Covid-19 vaccination and burgeoning research on vaccine hesitancy (VH), we conducted a scoping review to identify multilevel determinants of Covid-19 VH and under-vaccination among marginalized populations in the U.S. and Canada.

METHODS

Using the scoping review methodology developed by the Joanna Briggs Institute, we designed a search string and explored 7 databases to identify peer-reviewed articles published from January 1, 2020-October 25, 2022. We combine frequency analysis and narrative synthesis to describe factors influencing Covid-19 VH and under-vaccination among marginalized populations.

RESULTS

The search captured 11,374 non-duplicated records, scoped to 103 peer-reviewed articles. Among 14 marginalized populations identified, African American/Black, Latinx, LGBTQ+, American Indian/Indigenous, people with disabilities, and justice-involved people were the predominant focus. Thirty-two factors emerged as influencing Covid-19 VH, with structural racism/stigma and institutional mistrust (structural)(n = 71) most prevalent, followed by vaccine safety (vaccine-specific)(n = 62), side effects (vaccine-specific)(n = 50), trust in individual healthcare provider (social/community)(n = 38), and perceived risk of infection (individual)(n = 33). Structural factors predominated across populations, including structural racism/stigma and institutional mistrust, barriers to Covid-19 vaccine access due to limited supply/availability, distance/lack of transportation, no/low paid sick days, low internet/digital technology access, and lack of culturally- and linguistically-appropriate information.

DISCUSSION

We identified multilevel and complex drivers of Covid-19 under-vaccination among marginalized populations. Distinguishing vaccine-specific, individual, and social/community factors that may fuel decisional ambivalence, more appropriately defined as VH, from structural racism/structural stigma and systemic/institutional barriers to vaccination access may better support evidence-informed interventions to promote equity in access to vaccines and informed decision-making among marginalized populations.

Is Covid-19 "vaccine uptake" in postsecondary education a "problem"? A critical policy inquiry

Since the launch of the Covid-19 global vaccination campaign, postsecondary institutions have strongly promoted vaccination, often through mandates, and the academic literature has identified "vaccine uptake" among postsecondary students as a problem deserving monitoring, research, and intervention. However, with the admission that vaccines do not stop viral spread, that older-age and co-morbidities are major determinants of poor outcomes, and that many vaccine side effects disproportionately affect the young, it cannot be assumed that a risk-benefit analysis favors vaccinating postsecondary students. Drawing from critical policy studies, I appraise the literature on Covid-19 vaccine uptake in postsecondary education. I find that this literature reflects the "scientific consensus," hardly acknowledging contradictory medical evidence, ignoring coercive elements underlying "vaccine acceptance," and neglecting ethical tensions built into the very design of vaccination policies. I discuss potential explanations for my findings, and their implications for academia's role in society in the COVID-19 era and beyond.

Comparison of knowledge, perception and willingness to receive covid-19 vaccines among tertiary students in Osun State, Nigeria

Background

Vaccination remains a potent way to curb the present covid-19 global pandemic.

Objectives

To assess knowledge, perception and willingness to receive covid-19 vaccines among tertiary students in Nigeria.

Methods

In the descriptive cross-sectional study, a sample size of 750 respondents was randomly selected from a university, polytechnic and college of education (COE) in Osun State, Nigeria. Independent sample T and Pearson correlation tests were used to analyse the responses.

Results

There was a significant increase in the percentage score of poor perception, relative to good perception among the university and polytechnic respondents. Among the COE respondents, significant increases in the percentage scores of poor knowledge, perception and willingness to receive covid-19 vaccines, relative to the good variables were observed. Weak positive correlations between knowledge and willingness & perception and willingness to receive covid-19 vaccines among all the respondents were noted. In addition, there was a significant increase in good perception to covid-19 vaccines among university and COE, relative to polytechnic respondents. Asides, a significant increase in good willingness to receive covid-19 vaccines was observed among the university, compared to COE respondents.

Conclusion

There is poor knowledge, perception and willingness to receive covid-19 vaccines among tertiary students in Osun State, Nigeria.

Covid-19 vaccines and investment performance: Evidence from equity funds in European Union

In this paper, we analyze the impact of the marketing authorization of EMA-approved vaccines on the returns of equity funds in the EU. Using the event study methodology, we report that the introduction of all vaccines had a positive impact on the funds' returns. Higher abnormal returns were associated with the earlier vaccines, indicating the first-mover advantage and the abnormal returns were persistent across several event windows. The findings imply that equity markets welcomed the vaccine administration as an important pharmaceutical intervention to support the quasi-revival of business activities. Consequently, there was a significant uplift in the economic bottom line.

Assessing COVID-19 vaccine effectiveness against Omicron subvariants: Report from a meeting of the World Health Organization

Emerging in November 2021, the SARS-CoV-2 Omicron variant of concern exhibited marked immune evasion resulting in reduced vaccine effectiveness against SARS-CoV-2 infection and symptomatic disease. Most vaccine effectiveness data on Omicron are derived from the first Omicron subvariant, BA.1, which caused large waves of infection in many parts of the world within a short period of time. BA.1, however, was replaced by BA.2 within months, and later by BA.4 and BA.5 (BA.4/5). These later Omicron subvariants exhibited additional mutations in the spike protein of the virus, leading to speculation that they might result in even lower vaccine effectiveness. To address this question, the World Health Organization hosted a virtual meeting on December 6, 2022, to review available evidence for vaccine effectiveness against the major Omicron subvariants up to that date. Data were presented from South Africa, the United Kingdom, the United States, and Canada, as well as the results of a review and meta-regression of studies that evaluated the duration of the vaccine effectiveness for multiple Omicron subvariants. Despite heterogeneity of results and wide confidence intervals in some studies, the majority of studies showed vaccine effectiveness tended to be lower against BA.2 and especially against BA.4/5, compared to BA.1, with perhaps faster waning against severe disease caused by BA.4/5 after a booster dose. The interpretation of these results was discussed and both immunological factors (i.e., more immune escape with BA.4/5) and methodological issues (e.g., biases related to differences in the timing of subvariant circulation) were possible explanations for the findings. COVID-19 vaccines still provide some protection against infection and symptomatic disease from all Omicron subvariants for at least several months, with greater and more durable protection against severe disease.

Risk of carditis after three doses of vaccination with mRNA (BNT162b2) or inactivated (CoronaVac) covid-19 vaccination: a self-controlled cases series and a case-control study

Background

Large-scale comparative research exploring the risk after the third dose and after inactivated covid-19 vaccination is limited. This study aimed to assess the risk of carditis following three doses of BNT162b2 or CoronaVac.

Methods

We conducted a self-controlled case series (SCCS) and a case-control study using electronic health and vaccination records in Hong Kong. Carditis incidents within 28 days of covid-19 vaccination were included as cases. In the case-control study, up to 10 hospitalized controls were selected with stratified probability sampling by age, sex, and hospital admission (±1 day). The incidence rate ratios (IRRs) were reported from conditional Poisson regressions for SCCS, and adjusted odds ratios (ORs) were reported from multivariable logistic regressions.

Findings

A total of 8,924,614 doses of BNT162b2 and 6,129,852 doses of CoronaVac were administered from February 2021 to March 2022. The SCCS detected increased carditis risks after BNT162b2: 4.48 (95%confidence interval [CI]:2.99-6.70] in 1-14 days and 2.50 (95%CI:1.43-4.38) in 15-28 days after first dose; 10.81 (95%CI:7.63-15.32) in 1-14 days and 2.95 (95%CI:1.82-4.78) in 15-28 days after second dose; 4.72 (95%CI:1.40-15.97) in 1-14 days after third dose. Consistent results were observed from the case-control study. Risks were specifically found in people aged below 30 years and males. No significant risk increase was observed after CoronaVac in all primary analyses.

Interpretations

We detected increased carditis risks within 28 days after all three doses of BNT162b2 but the risk after the third doses were not higher than that of the second dose when compared with baseline period. Continuous monitoring of carditis after both mRNA and inactivated covid-19 vaccines is needed.

Funding

: This study was funded by Hong Kong Health Bureau (COVID19F01).

Characterizing discourses about COVID-19 vaccines on Twitter: a topic modeling and sentiment analysis approach

BACKGROUND

Evidence-based health communication is crucial for facilitating vaccine-related knowledge and addressing vaccine hesitancy. To that end, it is important to understand the discourses about COVID-19 vaccination and attend to the publics' emotions underlying those discourses.

METHODS

We collect tweets related to COVID-19 vaccines from March 2020 to March 2021. In total, 304,292 tweets from 134,015 users are collected. We conduct a Latent Dirichlet Allocation (LDA) modeling analysis and a sentiment analysis to analyze the discourse themes and sentiments.

RESULTS

This study identifies seven themes of COVID-19 vaccine-related discourses. Vaccine advocacy (24.82%) is the most widely discussed topic about COVID-19 vaccines, followed by vaccine hesitancy (22.29%), vaccine rollout (12.99%), vaccine facts (12.61%), recognition for healthcare workers (12.47%), vaccine side effects (10.07%), and vaccine policies (4.75%). Trust is the most salient emotion associated with COVID-19 vaccine discourses, followed by anticipation, fear, joy, sadness, anger, surprise, and disgust. Among the seven topics, vaccine advocacy tweets are most likely to receive likes and comments, and vaccine fact tweets are most likely to receive retweets.

CONCLUSIONS

When talking about vaccines, publics' emotions are dominated by trust and anticipation, yet mixed with fear and sadness. Although tweets about vaccine hesitancy are prevalent on Twitter, those messages receive fewer likes and comments than vaccine advocacy messages. Over time, tweets about vaccine advocacy and vaccine facts become more dominant whereas tweets about vaccine hesitancy become less dominant among COVID-19 vaccine discourses, suggesting that publics become more confident about COVID-19 vaccines as they obtain more information.

Knowledge, attitudes, and behaviors toward COVID-19 vaccination in a sample of Italian healthcare workers

Vaccine hesitancy in healthcare workers (HCWs) has been studied for various contagious diseases, but there is still insufficient knowledge about this phenomenon for COVID-19. We developed and validated a knowledge, attitude, and practice survey of 39 questions to assess Italian HCWs' hesitancy toward vaccination in general (general hesitancy), COVID-19 vaccination (COVID-19 hesitancy), and public health injunctive measures (refusal of obligations). The survey was administered through a web platform between July and November 2021. Three multivariable logistic regressions were performed to evaluate the association between the explored dimensions of hesitancy and the potential determinants investigated. Out of 2,132 respondents with complete answers, 17.0% showed to be generally hesitancy toward vaccination, 32.3% were hesitant on COVID-19 vaccination, while 18.8% were categorized as refusing obligations. A significant protective effect against all three dimensions of hesitancy was found for increasing fear of COVID-19, advising COVID-19 vaccination to relatives and patients, having received flu vaccination in the previous year and having higher levels of education. Better self-rated knowledge about COVID-19 vaccines and reading up institutional sources were significantly protective against general and COVID-19 hesitancy, while being a physician rather than another healthcare professional was protective only against COVID-19 hesitancy. Conversely, increasing age and referring to colleagues to expand knowledge about COVID-19 were positively associated with COVID-19 hesitancy. The determinants of general hesitancy, COVID-19 hesitancy and the refusal of obligations are mostly overlapping. Given the great influence they exert on patients and communities, it is pivotal to limit HCWs vaccine hesitancy through appropriate training activities.

The mediating role of product judgment and country of origin effect on health literacy and behavioral intention: A study on COVID-19 vaccines perception of Turkish consumers

This study is conducted on people in Turkey who had at least one dose of vaccination and it evaluates their differences in attitude in terms of health literacy, product judgment, the country of origin, intention to recommend and motivation to boycott. The 393 vaccine consumers were selected through convenient sampling and the data was collected through online questionnaires. The data was later analyzed by SPSS and AMOS. Normality, reliability tests and frequency analysis were conducted on the data. Afterward, a correlation was calculated using factor loadings to determine the relationship between the variables. The last was conducting the PATH analysis. Some consumers are prejudiced toward COVID-19 vaccines due to perceived distrust, hesitation, and lack of product information. Determining the prejudices of consumers, underlying causes and making inferences will provide more useful information on COVID-19 vaccines to health institutions, vaccine manufacturers, consumers and other organizations.

Covid-19 vaccines and variants of concern: A review

Since the outbreak of coronavirus disease 2019 (Covid-19) in December 2019, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the number of confirmed infections has risen to more than 242 million worldwide, with nearly 5 million deaths. Currently, nine Covid-19 vaccine candidates based on the original Wuhan-Hu-1 strain are at the forefront of vaccine research. All nine had an efficacy over 50% against symptomatic Covid-19 disease: NVX-CoV2373 (∼96%), BNT162b2 (∼95%), mRNA-1273 (∼94%), Sputnik V (∼92%), AZD1222 (∼81%), BBIBP-CorV (∼79%), Covaxin (∼78%), Ad26.CoV.S (∼66%) and CoronaVac (∼51%). However, vaccine efficacy (VE) can be jeopardised by the rapid emergence and spread of SARS-CoV-2 variants of concern (VOCs) that could escape from neutralising antibodies and/or cell-mediated immunity. Rare adverse events have also been reported soon after administration of viral vector and mRNA vaccines. Although many Covid-19 vaccines have been developed, additional effective vaccines are still needed to meet the global demand. Promising Covid-19 vaccines such as WIBP-CorV, AD5-nCOV, ZyCoV-D, CVnCoV, EpiVacCorona and ZF2001 have advanced to clinical studies. This review describes the most relevant mutations in the SARS-CoV-2 spike protein, discusses VE against VOCs, presents rare adverse events after Covid-19 vaccination and introduces some promising Covid-19 vaccine candidates.

[ARN COVID-19 COMIRNATY Vaccine desensitization in a case of PEG Severe Immediate Hypersensitivity]

Vaccination is the most efficient way to fight the Covid epidemic. However, suspicion of severe hypersensitivity to PEG (PolyEthylen Glycol) usually constitutes a vaccine contraindication. We report the case of a patient with a proven allergy to PEG and skin sensitization to the COMIRNATY vaccine (PEG in its composition). He was able to benefit from the vaccine under the 5-step desensitization protocol. Conclusions: Specific allergological management should be offered to patients suspected of severe hypersensitivity to PEG and other vaccine excipients. We propose a solution for Comirnaty administration for patients with a proven severe allergy to PEG.

Does a major change to a COVID-19 vaccine program alter vaccine intention? A qualitative investigation

Background

On 8th April 2021, the Australian Technical Advisory Group on Immunisation (ATAGI) made the Pfizer-BioNtech (Comirnaty) vaccine the “preferred” vaccine for adults in Australia aged < 50 years due to a risk of thrombosis with thrombocytopenia syndrome (TTS) following AstraZeneca vaccination. We sought to understand whether this impacted COVID-19 vaccine intentions.

Method

We undertook qualitative interviews from February – April 2021 before and after the program change with 28 adults in Perth, Western Australia. Using our COVID-19 vaccine intentions model, we assessed changes in participants’ COVID-19 vaccine intention before and after the program change. Participants were classified as 1) ‘acceptors’: no concerns about COVID-19 vaccine safety, efficacy, access and would accept whatever vaccine is offered, 2) ‘cautious acceptors’: some concerns and would prefer a particular vaccine brand but would accept whatever is offered, 3) ‘Wait awhile’: for more data, easier access, for another vaccine brand, a greater perceived COVID-19 threat or until mandatory, or 4) ‘refuser’: no intention to vaccinate due to concerns about safety and/or efficacy.

Results

Before the change, 7/18 of those aged < 50 years were ‘acceptors,’ 10/18 were ‘cautious acceptors’ and 1/18 was ‘wait awhile.’ Overall, 14/18 participants had the same COVID-19 vaccine intention after the change; 4/18 became more concerned. For those aged ≥ 50 years and before the change, 5/10 were ‘acceptors’ and 5/10 were ‘cautious acceptors.’ After the change, 8/10 still had the same COVID-19 vaccine intention; 2/10 became more cautious. The major concern before the program change was COVID-19 vaccines having different vaccine efficacy; the concern pivoted to safety.

Conclusion

The majority of participants were ‘cautious acceptors’ who intended on being vaccinated; many had this intention before and after the program change. The Australian government, health care providers and media need to better address COVID-19 vaccine concerns to assist those with COVID-19 vaccine intentions receive a vaccine.

COVID-19 vaccination acceptability in the UK at the start of the vaccination programme: a nationally representative cross-sectional survey (CoVAccS - wave 2)

Objectives

Investigate factors associated with the intention to have the COVID-19 vaccination following initiation of the UK national vaccination programme.

Study design

An online cross-sectional survey completed by 1500 adults (13th–15th January 2021).

Methods

Linear regression analyses were used to investigate associations between intention to be vaccinated for COVID-19 and sociodemographic factors, previous influenza vaccination, attitudes and beliefs about COVID-19 and COVID-19 vaccination and vaccination in general. Participants’ main reasons for likely vaccination (non-)uptake were also solicited.

Results

73.5% of participants (95% CI 71.2%, 75.7%) reported being likely to be vaccinated against COVID-19, 17.3% (95% CI 15.4%, 19.3%) were unsure, and 9.3% (95% CI 7.9%, 10.8%) reported being unlikely to be vaccinated. The full regression model explained 69.8% of the variance in intention. Intention was associated with: having been/intending to be vaccinated for influenza last winter/this winter; stronger beliefs about social acceptability of a COVID-19 vaccine; the perceived need for vaccination; adequacy of information about the vaccine; and weaker beliefs that the vaccine is unsafe. Beliefs that only those at serious risk of illness should be vaccinated and that the vaccines are just a means for manufacturers to make money were negatively associated with vaccination intention.

Conclusions

Most participants reported being likely to get the COVID-19 vaccination. COVID-19 vaccination attitudes and beliefs are a crucial factor underpinning vaccine intention. Continued engagement with the public with a focus on the importance and safety of vaccination is recommended.

The relationship of Covid-19 vaccine attitude with life satisfaction, religious attitude and Covid-19 avoidance in Turkey

The aim of this study was to determine the relationship between the attitudes toward the Covid-19 vaccine and life satisfaction, religious attitude, and the avoidance attitudes from Covid-19. This cross-sectional study was conducted online between 24 December 2020 and 06 January 2021 among adults age 18 years and older. Total 1033 people participated in the study. The data were collected using the Attitudes Toward Covid-19 Vaccine, Avoiding Attitudes from COVID-19, Religious Attitude Scale and Contentment with Life Assessment Scale. According to the "agree" and "strongly agree" responses of participants to the positive attitude items; the participants responded to the question "Who would you like to be vaccinated?" as follows: everyone (31.3%); family members (31.8%); and themselves (28.1%). The rates of those who responded to these items as "indecisive" were 44.5-48.2%. While there was no significant relationship between the COVID-19 vaccine attitude with the avoidance attitude from COVID-19 and the religious attitude; life satisfaction was found to be significant. It was observed that factors such as increasing fear of COVID-19 contagion, being male, increased life satisfaction, other relatives infected with Covid-19, increasing perceived health status, increased age, and not being a worker-tradesman increase the probability of having a positive attitude toward COVID-19 vaccine. It was observed that about one-third of the participants think the COVID-19 vaccine is protective and supports its administration, that almost half of them were undecided on these issues. Thus, it can be said that society needs accurate information about vaccination.

The relationship of Covid-19 vaccine attitude with life satisfaction, religious attitude and Covid-19 avoidance in Turkey

The aim of this study was to determine the relationship between the attitudes toward the Covid-19 vaccine and life satisfaction, religious attitude, and the avoidance attitudes from Covid-19. This cross-sectional study was conducted online between 24 December 2020 and 06 January 2021 among adults age 18 years and older. Total 1033 people participated in the study. The data were collected using the Attitudes Toward Covid-19 Vaccine, Avoiding Attitudes from COVID-19, Religious Attitude Scale and Contentment with Life Assessment Scale. According to the "agree" and "strongly agree" responses of participants to the positive attitude items; the participants responded to the question "Who would you like to be vaccinated?" as follows: everyone (31.3%); family members (31.8%); and themselves (28.1%). The rates of those who responded to these items as "indecisive" were 44.5-48.2%. While there was no significant relationship between the COVID-19 vaccine attitude with the avoidance attitude from COVID-19 and the religious attitude; life satisfaction was found to be significant. It was observed that factors such as increasing fear of COVID-19 contagion, being male, increased life satisfaction, other relatives infected with Covid-19, increasing perceived health status, increased age, and not being a worker-tradesman increase the probability of having a positive attitude toward COVID-19 vaccine. It was observed that about one-third of the participants think the COVID-19 vaccine is protective and supports its administration, that almost half of them were undecided on these issues. Thus, it can be said that society needs accurate information about vaccination.

A review of approved COVID-19 vaccines

In the past one and half year elapsed since the identification of the SARS-CoV-2 virus and its genome, an extraordinary effort by the scientific community has led to the development of many vaccine projects. More than ten vaccine candidates throughout the world have been granted approval for emergency use. Existing data suggest that these vaccines have the potential to protect individuals and curb the spread of COVID-19 pandemic. However, long term side-effects and certain unresolved issues associated with vaccine use need to be assessed as the time passes. This study reviews the most recent data of 12 vaccines which have been approved for use and presents information on their doses, composition, mechanism of action, side effects, etc.

Lessons from Biomedical Innovation during World War II

The United States developed penicillin and vaccines during World War II. The partnership of government, industry, and academe was crucial. In an essay, Vannevar Bush credited that partnership with the technological achievements that led to winning the war. The policies used to address the Covid-19 pandemic closely resemble how penicillin was developed, and similarly produced spectacular success in the form of RNA-based vaccines. But will today's politics of hyperpartisan vitriol and credit-mongering that pit industry against government and academe prevent carrying that success into the postpandemic era?

Overview of the Main Anti-SARS-CoV-2 Vaccines: Mechanism of Action, Efficacy and Safety

This review takes into consideration the principal vaccines developed against the SARS-CoV-2 in this unprecedented period of Covid-19 pandemic. We evaluated the mechanism of action of each vaccine as well as the efficacy, the safety and the storage temperature. In addition, the problem of the dose units, the vaccinal strategy, the activity of alternative compounds such as the monoclonal antibodies and especially the issue of the virus variants were also described in detail. Four vaccines are currently used in Italy: Pfizer-BioNTech mRNA BNT162b2 (Comirnaty) (USA), Moderna mRNA 1273 (USA), Astra-Zeneca ChAdOx1-S (recombinant) viral vector adenovirus belonging to Oxford (UK) and Pomezia (Italy), Janssen (two recombinant viral vector adenoviruses) belonging to Johnson & Johnson (USA). The efficacy of Pfizer and Moderna for preventing disease or severe disease results 95-87.5% and 94.5-100%, respectively. The efficacy of Astra-Zeneca and Janssen is about 70% and 65%, respectively; in the case of Janssen, it depends on the geographical area ranging from 72% to 57%. The problem of the administrated doses (one dose, two doses from the same vaccine or from different vaccines, half dose) is also discussed. The vaccination strategy based on the age group remains the simplest, most transparent and fair criterion. This strategy is also based on accelerating the administration of the vaccines, so that as many subjects as possible can be vaccinated quickly for achieving the "herd immunity". The monoclonal antibodies appeared to be a valid solution for the treatment of Covid-19 disease. Two antibodies (bamlanivimab and etesevimab) have just been approved by the FDA. They could also be used for the infection by virus variants which represent a big problem due to their higher transmissibility and virulence and to their lower response to the vaccines.

Information in Spanish on YouTube about Covid-19 vaccines

Our objective was to analyze the sources, characteristics, tone, and content of the most viewed YouTube videos in Spanish about Covid-19 vaccines. In February 2021, a search was carried out on YouTube using the terms "Vacuna Covid," "Vacuna coronavirus," and "Vacuna Covid19." Associations between tone, source, and others variables (e.g. number of views or dislikes) were studied with a Mann-Whitney U-test and a chi-square test. A total of 118 videos were analyzed; 63.6% were originated from Mexico and the USA; media created 57.6% of the videos. Positive tone was observed in 53.4%. The most discussed topics were target groups for vaccination (38.9%) and safety (43.2%). The 68 videos produced by media accumulated 31,565,295 views (55.0% of views), and the 19 videos created by health professionals obtained 10,742,825 views (18.7% of views). A significantly smaller number of likes was obtained in videos of media compared to those created by health professionals (p = .004). Videos made by health professionals, compared to those of media, showed a greater positive tone (OR = 3.09). Hoaxes/conspiracy theories were identified in 1.7% of the videos. Monitoring that the information on YouTube about Covid-19 vaccines is reliable should be a central part of Covid-19 vaccination campaigns.