Quantifying the Population-Level Effect of the COVID-19 Mass Vaccination Campaign in Israel: A Modeling Study.

Background: Estimating real-world vaccine effectiveness is challenging as a variety of population factors can impact vaccine effectiveness. We aimed to assess the population-level reduction in cumulative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases, hospitalizations, and mortality due to the BNT162b2 mRNA coronavirus disease 2019 (COVID-19) vaccination campaign in Israel during January-February 2021. Methods: A susceptible-infected-recovered/removed (SIR) model and a Dynamic Survival Analysis (DSA) statistical approach were used. Daily counts of individuals who tested positive and of vaccine doses administered, obtained from the Israeli Ministry of Health, were used to calibrate the model. The model was parameterized using values derived from a previous phase of the pandemic during which similar lockdown and other preventive measures were implemented in order to take into account the effect of these prevention measures on COVID-19 spread. Results: Our model predicted for the total population a reduction of 648 585 SARS-CoV-2 cases (75% confidence interval [CI], 25 877-1 396 963) during the first 2 months of the vaccination campaign. The number of averted hospitalizations for moderate to severe conditions was 16 101 (75% CI, 2010-33 035), and reduction of death was estimated at 5123 (75% CI, 388-10 815) fatalities. Among children aged 0-19 years, we estimated a reduction of 163 436 (75% CI, 0-433 233) SARS-CoV-2 cases, which we consider to be an indirect effect of the vaccine. Conclusions: Our results suggest that the rapid vaccination campaign prevented hundreds of thousands of new cases as well as thousands of hospitalizations and fatalities and has probably averted a major health care crisis.

The Association of Previous Vaccination with Live-Attenuated Varicella Zoster Vaccine and COVID-19 Positivity: An Israeli Population-Based Study.

The Bacillus Calmette-Guérin (BCG) vaccine affords indirect protection against COVID-19, which is presumably due to priming of the innate immune system. It was hypothesized that the live attenuated Varicella Zoster (LAVZ) vaccine, recommended for the elderly population, would also protect against COVID-19 infection. A retrospective population-based cross-sectional study was conducted using the Leumit Health Services (LHS) database. LAVZ-vaccinated patients were matched with controls based on a propensity score model using 1:9 nearest-neighbor matching. Matching was based on age, gender, and the presence of some chronic disorders, which were selected according to their association with COVID-19 infection. Multivariate logistic regression analyses, adjusted for sex, age, smoking status, comorbidities, and chronic medications associated with COVID-19 risk, were used to estimate the association between LAVZ vaccination and COVID-19 RT-PCR results. Subjects (625) vaccinated with LAVZ and RT-PCR-tested for COVID-19 were identified. After 1:9 matching of subjects who received the LAVZ vaccine, 6250 subjects were included in the study. Multivariate logistic regression analysis demonstrated a significant and independent negative association between having received the LAVZ vaccine and the likelihood of COVID-19 infection (adjusted OR = 0.47 (95% CI 0.33-0.69, p < 0.001)). This association was further strengthened after separate analysis based on the time of LAVZ vaccination before COVID-19 RT-PCR testing. Individuals aged ≥50 years vaccinated with LAVZ had a decreased likelihood of being tested positive for COVID-19.

Reopening Schools and the Dynamics of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infections in Israel: A Nationwide Study.

BACKGROUND: Benefits of school reopening must be weighed against the morbidity and mortality risks and the impact of enhancing spread of coronavirus disease 2019 (COVID-19). We investigated the effects of school reopening and easing of social-distancing restrictions on dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Israel between March and July 2020. METHODS: We examined the nationwide age-wise weekly incidence, prevalence, SARS-CoV-2 polymerase chain reaction tests, their positivity, COVID-19 hospitalizations, and associated mortality. Temporal differences in these parameters following school reopening, school ending, and following easing of restrictions such as permission of large-scale gatherings were examined. RESULTS: Incidence of SARS-CoV-2 infections gradually increased following school reopening in all age groups, with a significantly higher increase in adults than children. Higher rate ratios (RRs) of sample positivity rates 21-27 days following school reopening relative to positivity rates prior to openings were found for the age groups 40-59 (RR, 4.72; 95% CI, 3.26-6.83) and 20-39 (RR, 3.37 [2.51-4.53]) years, but not for children aged 0-9 (RR, 1.46 [.85-2.51]) and 10-19 (RR, .93 [.65-1.34]) years. No increase was observed in COVID-19-associated hospitalizations and deaths following school reopening. In contrast, permission of large-scale gatherings was accompanied by increases in incidence and positivity rates of samples for all age groups, and increased hospitalizations and mortality. CONCLUSIONS: This analysis does not support a major role of school reopening in the resurgence of COVID-19 in Israel. Easing restrictions on large-scale gatherings was the major influence on this resurgence.

Comparison of the medical burden of COVID-19 with seasonal influenza and measles outbreaks.

AIM: To examine and compare the medical burden of measles, influenza and COVID-19 outbreaks in the city of Bnei Brak, Israel. METHODS: The study was conducted during 2018-2021. The numbers of hospitalisations for these infections and their complications were recorded. Hospitalisation rates were determined by using the number of children residing in Bnei Brak and hospitalised with these infections during the study period as the numerators. The denominators were the estimated paediatric cases of measles, influenza and COVID-19 in Bnei Brak and were calculated under both pragmatic and conservative assumptions. RESULTS: A total of 247, 65 and 32 children were hospitalised with influenza, COVID-19 and measles respectively. Complication rates were higher following measles than after influenza and SARS-CoV-2 infections. Hospitalisation rates were 10% for measles, 0.6%-1.2% for influenza and 0.15% - 0.25% for COVID-19 infections. Relative risks (RR) with 95% confidence intervals (CI) for hospitalisation following measles compared with COVID-19 ranged from 42 (26.3-67.3) to 70.1 (43.8-112.1), while the relative risks for influenza hospitalisation ranged from 2.5 (1.83-3.41) to 8.2 (6.0-11.2), compared with COVID-19 infection. CONCLUSION: Hospitalisation rates and direct medical burdens of measles and influenza were significantly higher than those of COVID-19 infection in children.

Intrafamilial Spread and Altered Symptomatology of SARS-CoV-2, During Predominant Circulation of Lineage B.1.1.7 Variant in Israel.

The dynamics of intrafamilial spread of SARS-CoV-2 during January-February 2021 when variant B.1.1.7 predominated were compared with data from April to May 2020, when other circulating variants prevailed. Much higher intrafamilial transmission rates among all age groups, in particular in young children, and lower rates of sensory impairment were demonstrated during January-February 2021.

Coronavirus Disease Spread during Summer Vacation, Israel, 2020.

The relative increase in coronavirus disease incidence during summer 2020 in Israel was most prominent in young children. This finding contrasts with the lower increase in incidence observed in children than in adults during the school attendance period. School closure without lockdown conditions might not be independently effective at reducing spread.

Titers of SARS CoV-2 antibodies in cord blood of neonates whose mothers contracted SARS CoV-2 (COVID-19) during pregnancy and in those whose mothers were vaccinated with mRNA to SARS CoV-2 during pregnancy.

OBJECTIVE: We compared neonatal immunity after vaccination against SARS-CoV-2 during pregnancy to that achieved after maternal infection. STUDY DESIGN: We tested cord blood from women infected with SARS-CoV-2 during pregnancy (group 1, n = 29), women who were vaccinated during pregnancy (group 2, n = 29) and from women not infected and not vaccinated (Group 3, n = 21) for titers of antibodies to both SARS-CoV-2 spike and 'N' proteins. RESULTS: Seventy-nine women were included: Antibodies against SARS-CoV-2 spike protein were detected in all samples from Group 1 and 2. Antibodies to the 'N' protein were detected in 25/29 samples in Group 1. None of the samples from Group 3 had antibodies to either protein. Mean titers of SARS-CoV-2 antibodies were significantly higher in Group 2 than in Group 1 (p < 0.05). CONCLUSIONS: Neonates born to mothers vaccinated during pregnancy have higher antibody titers and may therefore have more prolonged protection than those born to women infected during pregnancy.

COVID-19 in a Subset of Hospitalized Children in Israel.

BACKGROUND: Most pediatric coronavirus disease 2019 (COVID-19) is mild. We assessed nationally severe COVID-19, including pediatric inflammatory multisystem syndrome (PIMS), in hospitalized children. METHODS: An ongoing, prospective, national surveillance was conducted from March 2020 through March 2021, at 20 hospitals treating children <18 years across Israel (~75% of Israeli hospitals). RESULTS: Overall, 1007 cases (439 outpatients and 568 hospitalized) identified represent 0.35% of pediatric COVID-19 nationwide (n = 291 628). Of hospitalized cases, 464 (82%), 48 (8%), and 56 (10%) had mild, moderate/severe, and PIMS disease, respectively. The mean ± SD age was 5.6 ± 6.4 years. In mild, moderate/severe, and PIMS disease, 55%, 23%, and 4% of patients were <1 year old, respectively. Obesity was reported in 1%, 4%, and 13% of patients, respectively (P < .001). The most common symptom was fever in 67%, 60%, and 100%, respectively, whereas respiratory symptoms were documented in 33%, 41%, and 38% of patients, respectively. Lymphopenia was recorded in 25%, 60%, and 86% of cases, respectively. PIMS diagnosis was mainly serology-based (in 59%). Gastrointestinal symptoms, cardiovascular involvement, rash, and conjunctivitis were noted in 82%, 61%, 57%, and 34% of PIMS episodes, respectively. Elevated C-reactive protein (100%), ferritin, troponin, D-dimer, low albumin, and thrombocytopenia were common in PIMS. Echocardiography revealed pathological findings in 33% of patients. PIMS mainstay treatment included corticosteroids (77%) and intravenous immunoglobulin (53%). No mortality was recorded. CONCLUSIONS: At a national level, pediatric COVID-19 is mild, even in hospitalized cases, with only a third presenting with respiratory involvement. PIMS is rare, but necessitates a high index of suspicion, and with suitable treatment prognosis is favorable.