Saad B Omer

Saad B Omer
Yale University | YU · Yale Institute for Global Health

MBBS, MPH, PhD

About

619
Publications
162,717
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80,789
Citations
Citations since 2017
364 Research Items
54939 Citations
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Publications

Publications (619)
Article
Involvement of women is critical in establishing guidelines
Article
The continued success of vaccines, one of the most effective public health interventions, depends on high rates of acceptance. Vaccine refusal in the United States has increased since the late 1990s.¹ This trend has coincided with an increase in vaccine safety concerns. Such concerns result from easy recall of adverse events, misinformation, and hu...
Article
Full-text available
Background: Vaccination coverage with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine in pregnancy or immediately postpartum has been low. Limited data exist on rigorously evaluated interventions to increase maternal vaccination, including Tdap. Tailored messaging based on the Elaboration Likelihood Model (ELM) fr...
Article
Infants can be protected against a variety of dangerous infections early in life through immunity transferred from their mothers. This article reviews the efficacy of maternal immunization in the prevention of infections in babies too young to be immunized directly.
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Despite high measles vaccination rates in the United States, imported measles cases have led to outbreaks in the United States. These outbreaks have not led to sustained measles transmission; however, with each birth cohort of children not fully vaccinated against measles, measles-susceptible individuals accumulate in the population. The total numb...
Preprint
Full-text available
Non-pharmaceutical interventions minimize social contacts, hence the spread of SARS-CoV-2. We quantified two-day contact patterns among USA employees from 2020–2021 during the COVID-19 pandemic. Contacts were defined as face-to-face conversations, involving physical touch or proximity to another individual and were collected using electronic diarie...
Article
Background: New data on COVID-19 may influence the stringency of containment policies, but these potential effect are not understood. We aimed to understand the associations of new COVID-19 cases and deaths with policy stringency globally and regionally. Methods: We modelled the marginal effects of new COVID-19 cases and deaths on policy stringe...
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Amidst an unprecedented Monkeypox outbreak, we aimed to measure knowledge, attitudes, practices and Monkeypox vaccination intentions among the U.S. adult population. We conducted an online cross-sectional survey, representative of the U.S. adult general public in June 2022. We asked participants whether they would receive a Monkeypox vaccine, if th...
Article
In October 2021, Emergency Use Authorization of Coronavirus Disease 2019 (COVID-19) vaccines was granted for children aged 5-11. To ensure vaccine uptake in children upon approval, California will implement a state-wide executive order mandating COVID-19 vaccination for school children following full US FDA approval. This study uses survey data col...
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Background Many pregnant women and parents have concerns about vaccines. This analysis examined the impact of MomsTalkShots, an individually tailored educational application, on vaccine attitudes of pregnant women and mothers. Methods MomsTalkShots was the patient-level component of a multi-level intervention to improve maternal and infant vaccine...
Article
Importance Patients from racially and ethnically minoritized populations, such as Black and Hispanic patients, may be less likely to receive evidence-based COVID-19 treatments than White patients, contributing to adverse clinical outcomes. Objective To determine whether clinical treatments and outcomes among patients hospitalized with COVID-19 wer...
Preprint
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Importance All U.S. states provided Covid-19 vaccine access to frontline healthcare workers first, but after that, states varied in whether they gave earlier access to the elderly, versus the vulnerable with comorbidities, or school employees or essential workers, reflecting the underlying scientific and policy uncertainty. Objective To evaluate i...
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Background Clinical pediatric TB diagnosis may lead to over-diagnosis particularly among children with HIV (CHIV). We assessed the performance of monocyte-lymphocyte ratio (MLR) as a diagnostic biomarker and constructed a clinical prediction score to improve specificity of TB diagnosis in CHIV with limited access to microbiologic testing. Methods...
Preprint
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We examined the effectiveness of maternal vaccination against SARS-CoV-2 infection in 30,288 infants born at Kaiser Permanente Northern California from December 15, 2020, to May 31, 2022. Using Cox regression, the effectiveness of maternal vaccination was 85% (95% confidence interval [CI]: 67, 93), 64% (CI: 43, 78) and 57% (CI: 36,71) during the fi...
Preprint
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The emergence of the SARS-CoV-2 Omicron sublineages resulted in drastically increased transmission rates and reduced protection from vaccine-induced immunity. To counteract these effects, multiple booster strategies were used in different countries, although data comparing their efficiency in improving protective immunity remains sparse, especially...
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Introduction: Given their central role in supporting children's development, childcare professionals' overall physical and mental health is important. We evaluated the prevalence of chronic diseases, depression, and stress levels during the COVID-19 pandemic among US childcare professionals. Methods: Data were obtained from US childcare professi...
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Influenza causes significant mortality and morbidity in the United States (US). Employees are exposed to influenza at work and can spread it to others. The influenza vaccine is safe, effective, and prevents severe outcomes; however, coverage among US adults (50.2%) is below Healthy People 2030 target of 70%. These highlights need for more effective...
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Background The discovery of vaccines significantly reduced morbidity and mortality of infectious diseases and led to the elimination and eradication of some. Development of safe and effective vaccines is a critical step to the control of infectious diseases; however, there is the need to address vaccine hesitancy because of its potential impact on...
Article
In 2020, 26 million refugees resettled in a new country—fleeing their homes due to conflict and persecution. Due to low immunization coverage and underlying health conditions, refugees commonly face an increased risk of contracting vaccine-preventable diseases. We collected and analyzed existing routine immunization policies for refugees across 20...
Preprint
Full-text available
SARS-CoV-2 infection can result in the development of a constellation of persistent sequelae following acute disease called post-acute sequelae of COVID-19 (PASC) or Long COVID. Individuals diagnosed with Long COVID frequently report unremitting fatigue, post-exertional malaise, and a variety of cognitive and autonomic dysfunctions; however, the ba...
Article
Faced with the challenge of advising the World Health Organization on who should be the first to receive COVID-19 vaccines, an advisory group used an approach it hadn’t tried before. Faced with the challenge of advising the World Health Organization on who should be the first to receive COVID-19 vaccines, an advisory group used an approach it hadn’...
Preprint
Objective To understand the associations of COVID-19 cases and deaths with policy stringency globally and regionally. Methods We modeled the marginal effects of new COVID-19 cases and deaths on policy stringency (scored 0–100) in 175 countries and territories, adjusting for gross domestic product (GDP) per capita and health expenditure (% of GDP)....
Article
Objective To evaluate the impact of a multi-component intervention package of maternal immunization uptake in obstetric care clinics. Methods In a multi-level, cluster- and individually-randomized controlled trial we implemented an evidence-based intervention that targeted practice-, provider- and patient-level barriers to vaccine uptake. Obstetri...
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The SARS-CoV-2 Omicron variant is thought to cause less severe disease among the general population, but disease severity among at-risk populations is unknown. We performed a retrospective analysis using a matched cohort of United States veterans to compare the disease severity of subjects infected during Omicron and Delta predominant periods withi...
Article
Background Comparative effectiveness of COVID-19 vaccines across patient subgroups is poorly understood and essential to precisely target vaccination strategies. Methods We used the US Department of Veterans Affairs COVID-19 Shared Data Resource to identify veterans who utilize VA healthcare and had no documented SARS-CoV-2 infection before Decemb...
Preprint
While the Monkeypox outbreak is growing, little is known about the general public’s levels of knowledge, their trusted sources of information and attitudes towards a Monkeypox vaccine. In our representative survey of the US general public, we find that almost half the respondents (47%) feel that their knowledge level about Monkeypox is poor or very...
Article
The impact of Coronavirus Disease 2019 (COVID-19) mRNA vaccination on pregnancy and fertility has become a major topic of public interest. We investigated 2 of the most widely propagated claims to determine (1) whether COVID-19 mRNA vaccination of mice during early pregnancy is associated with an increased incidence of birth defects or growth abnor...
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Full-text available
Background Respiratory syncytial virus (RSV) is the most common cause of acute lower respiratory infection in young children. We previously estimated that in 2015, 33·1 million episodes of RSV-associated acute lower respiratory infection occurred in children aged 0-60 months, resulting in a total of 118 200 deaths worldwide. Since then, several com...
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Background The current SARS-CoV-2 vaccines may be less effective against the Omicron variant. With recent resurgence of SARS-CoV-2 cases, the role of booster doses of the vaccine needs to be highlighted. Methods Using a retrospective cohort study design emulating a target trial, we determined the relative effectiveness of a homologous booster dose...
Article
Objectives This study evaluated messages and communication approaches for maternal immunization uptake in Kenya. We identified persuasive communication aspects that would inform maternal immunization attitudes, intent, and vaccine uptake. Methods We conducted a two-phased mixed methods study with pregnant women and their male partners in three reg...
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Background The relationship between the use of nonpharmaceutical interventions and COVID-19 vaccination among U.S. child care providers remains unknown. If unvaccinated child care providers are also less likely to employ nonpharmaceutical interventions, then a vaccine mandate across child care programs may have larger health and safety benefits. M...
Preprint
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Parental hesitancy poses a serious threat to the success of the COVID-19 childhood vaccination campaign. We investigate whether adults' opinions on childhood vaccination can be influenced via two survey experiments in Italy (n=3,524 participants) and the UK (n=3,066 participants). Respondents were randomly assigned to: a “risk treatment” that highl...
Preprint
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SARS-CoV-2 Variants of Concern (VOCs) continue to reshape the trajectory of the COVID-19 pandemic. However, why some VOCs, like Omicron, become globally dominant while the spread of others is limited is not fully understood. To address this question, we investigated the VOC Mu, which was first identified in Colombia in late 2020. Our study demonstr...
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What types of public health messages are effective at changing people’s beliefs and intentions to practice social distancing to slow the spread of COVID-19? We conducted two randomized experiments in summer 2020 that assigned respondents to read a public health message and then measured their beliefs and behavioral intentions across a wide variety...
Article
Background: Knowledge of the vaccine effectiveness (VE) of a third or booster vaccine dose in preventing SARS-CoV-2 infection or its consequences is critical in developing recommendations for their use. We determined the relative VE of a three vs. two doses of an mRNA vaccine in preventing symptomatic SARS-CoV-2 infection, hospitalization, and sev...
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The recent emergence of the SARS-CoV-2 Omicron variant is raising concerns because of its increased transmissibility and by its numerous spike mutations with potential to evade neutralizing antibodies elicited by COVID-19 vaccines. Here, we evaluated the effects of a heterologous BNT162b2 mRNA vaccine booster on the humoral immunity of participants...
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Significance Chilblain diagnoses have increased during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and have been attributed to viral infection and a subsequent robust antiviral immune response. As a result, providers have managed these cases differently than idiopathic chilblains, which are associated with cold exposur...
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Background: The 2014-2016 Ebola epidemic disrupted childhood immunization in Sierra Leone, Liberia, and Guinea. After the epidemic, the Government of Sierra Leone prioritized community engagement to increase vaccination confidence and uptake. To support these efforts, we examined potential drivers of vaccination confidence and uptake in Sierra Leo...
Article
Background Persons on chronic hemodialysis have a significantly diminished humoral immune response to SARS-CoV-2 vaccines. Whether this translates to reduced vaccine effectiveness (VE) is unknown. Methods We used the US Department of Veterans Affairs COVID-19 Shared Data Resource to identify all Veterans who were tested for SARS-CoV-2 between Janu...
Article
Introduction: In 2015, California passed Senate Bill No. 277 (SB 277) and became the first state in more than 30 years to eliminate nonmedical exemptions to mandatory childhood immunizations for school entry. One concern that emerged was that the law created an incentive for parents to remove children from brick-and-mortar schools to bypass the im...
Article
Background Rare cases of thrombosis and thrombocytopenia (Thrombosis with Thrombocytopenia Syndrome or TTS) have been associated with two COVID-19 adenovirus vector vaccines: the CHAdOx1 nCoV-19 Vaxzevria (Oxford/AstraZeneca vaccine) and the JNJ-7836735 Johnson and Johnson vaccine (Janssen vaccine). It is unknown if TTS is a class-mediated effect o...
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Importance: It is not known how effective child masking is in childcare settings in preventing the transmission of SARS-CoV-2. This question is critical to inform health policy and safe childcare practices. Objective: To assess the association between masking children 2 years and older and subsequent childcare closure because of COVID-19. Desig...
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Objective Pakistan was one of the first South-Asian countries to introduce the ten-valent pneumococcal conjugate vaccine (PCV10) at the national level, using a 3+0 schedule without catchup, in 2013. Methods From 2014–18, fifteen children <2 years old were recruited every week in Matiari, Sindh, and nasopharyngeal swabs were collected. The samples...
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The COVID-19 pandemic led to a worldwide lockdown and school closures, which have placed a substantial mental health burden on children and college students. Through a systematic search of the literature on PubMed and Collabovid of studies published January 2020–July 2021, our findings of five studies on children and 16 studies on college students...
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Background Cruise ships provide an ideal setting for transmission of SARS-CoV-2, given the socially dense exposure environment. Aim To provide a comprehensive review of COVID-19 outbreaks on cruise ships. Methods PubMed was searched for COVID-19 cases associated with cruise ships between January and October 2020. A list of cruise ships with COVID...
Preprint
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The frequency of SARS-CoV-2 breakthrough infections in fully vaccinated individuals increased with the emergence of the Delta variant, particularly with longer time from vaccine completion. However, whether breakthrough infections lead to onward transmission remains unclear. Here, we conducted a study involving 125 patients comprised of 72 vaccinat...
Article
There is growing interest to use early cognitive ability to predict schooling and employment outcomes in low- and middle-income countries (LMICs). Rather than using educational attainment and school enrollment as predictors of future economic growth or of improving an individual’s earning potential, mounting evidence suggests that cognitive ability...
Preprint
The recent emergence of the SARS-CoV-2 Omicron variant is raising concerns because of its increased transmissibility and by its numerous spike mutations with potential to evade neutralizing antibodies elicited by COVID-19 vaccines. The Dominican Republic was among the first countries in recommending the administration of a third dose COVID-19 vacci...
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Full-text available
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in pregnancy is associated with a higher risk for severe morbidity and mortality when compared with infection in non-pregnant women of childbearing age. An increasing number of countries recommend immunization against SARS-CoV-2 in pregnant women. Recent studies provide prelimin...
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Antimicrobial resistance is an emerging public health concern. Ten-valent pneumococcal vaccine (PCV10) was introduced in Pakistan's Expanded Program on Immunization (EPI) in 2012 as a 3 1 0 schedule without catchup. From 2014 to 2018, children ,2 years were randomly selected in two rural union councils of Matiari, Pakistan. Nasopharyngeal swabs wer...
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Full-text available
The emergence of SARS-CoV-2 variants with mutations in major neutralizing antibody-binding sites can affect humoral immunity induced by infection or vaccination1–6. We analysed the development of anti-SARS-CoV-2 antibody and T cell responses in previously infected (recovered) or uninfected (naive) individuals that received mRNA vaccines to SARS-CoV...
Article
Background Breakthrough SARS-CoV-2 infections after vaccination have been reported. Outcomes among persons with breakthrough infection are poorly understood. Methods We identified all Veterans with a confirmed SARS-CoV-2 infection >14 days after the second dose of an mRNA vaccine between December 15, 2020 and June 30, 2021, and propensity-score ma...
Preprint
Full-text available
The impact of coronavirus disease 2019 (COVID-19) mRNA vaccination on pregnancy and fertility has become a major topic of public interest. We investigated two of the most widely propagated claims to determine 1) whether COVID-19 mRNA vaccination of mice during early pregnancy is associated with an increased incidence of birth defects or growth abno...
Article
Full-text available
The development of COVID-19 vaccines was an important breakthrough for ending the pandemic. However, people refusing to get vaccinated diminish the level of community protection afforded to others. In the United States, White evangelicals have proven to be a particularly difficult group to convince to get vaccinated. Here we investigate whether thi...
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Full-text available
Background The effectiveness of Severe Acute Respiratory Syndrome Coronavirus 2 vaccines after two doses needs to be demonstrated beyond clinical trials. Methods In a retrospective cohort assembled from a cross-institution comprehensive data repository, established patients of the health care system were categorized as having received no doses, on...
Article
Full-text available
Background Cruise ships provide an ideal setting for efficient transmission of SARS-CoV- 2 given a socially dense exposure environment. No systematic review of transmission of COVID-19 on cruise ships to date has been completed. Methods MEDLINE was searched in accordance with PRIMSA guidelines for COVID-19 cases associated with cruise ships. A lis...
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Aim There are few reliable estimates of the half-lives of maternal antibodies to the antigens found in the primary series vaccines. We aimed to calculate the half-lives of passively acquired diphtheria, tetanus and pertussis (DTP) antibodies in infants. We aimed to determine whether decay rates varied according to country, maternal age, gestational...
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Full-text available
Zusammenfassung Hintergrund Eltern stehen während der COVID-19-Pandemie vor einer Vielzahl persönlicher Herausforderungen, während sie gleichzeitig mit schulbezogenen Maßnahmen zur Pandemieeindämmung konfrontiert werden. Zielsetzung Dieser Beitrag fokussiert auf die Belastung von Eltern mit Kindern im Schulalter über verschiedene Phasen der COVID...
Preprint
Introduction: In 2015 California passed Senate Bill No. 277 (SB 277) and became the first state in over 30 years to eliminate nonmedical exemptions to mandatory childhood immunizations for school entry. One concern that emerged was that the law created an incentive for parents to remove children from brick-and-mortar schools to bypass the immunizat...
Article
Since the first case of COVID-19 was identified in the USA in January, 2020, over 46 million people in the country have tested positive for SARS-CoV-2 infection. Several COVID-19 vaccines have received emergency use authorisations from the US Food and Drug Administration, with the Pfizer–BioNTech vaccine receiving full approval on Aug 23, 2021. Whe...
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Full-text available
In the absence of widespread vaccination for COVID-19, governments and public health officials have advocated for the public to wear masks during the pandemic. The decision to wear a mask in public is likely affected by both beliefs about its efficacy and the prevalence of the behavior. Greater mask use in the community may encourage others to foll...
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Full-text available
Respiratory syncytial virus (RSV) is the leading cause of ALRI hospitalisations in Aboriginal infants specifically those aged<6 months. Maternally derived RSV antibody (Ab) can protect against severe RSV disease in infancy. However, the efficiency of transplacental transfer of maternal anti‐RSV Ab remains unknown in Aboriginal infants. We character...
Article
Widespread vaccination remains the best option for controlling the spread of COVID-19 and ending the pandemic. Despite the considerable disruption the virus has caused to people’s lives, many people are still hesitant to receive a vaccine. Without high rates of uptake, however, the pandemic is likely to be prolonged. Here we use two survey experime...
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Full-text available
As immunization campaigns are accelerating, understanding how to distribute the scarce doses of vaccines is of paramount importance and a quantitative analysis of the trade-offs involved in domestic-only versus cooperative distribution is still missing. In this study we use a network Susceptible-Infected-Removed (SIR) model to show circumstances un...
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Background Respiratory syncytial virus (RSV) is an important cause of infant morbidity and mortality and a potential target for maternal immunization strategies. However, data on the role of RSV in young infant deaths in developing countries are limited. Methods We conducted a community-based mortality surveillance from August 2018–March 2020 for...
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Background Estimating the real impact of respiratory syncytial virus (RSV) disease is key for the development of vaccines and treatments. Ascertaining the burden of community mortality due to RSV is challenging due to the lack of primary data. Therefore, conducting observational studies to determine the factors associated with community mortality d...