Nationwide seroprevalence of antibodies against SARS-CoV-2 in Israel.

The first local spread of COVID-19 in Israel was detected in March 2020. Due to the diversity in clinical presentations of COVID-19, diagnosis by RT-PCR alone might miss patients with mild or no symptoms. Serology testing may better evaluate the actual magnitude of the spread of infection in the population. This is the first nationwide seroprevalence study conducted in Israel. It is one of the most widespread to be conducted thus far, and the largest per-country population size. The survey was conducted between June 28 and September 14, 2020 and included 54,357 patients who arrived at the Health Maintenance Organizations to undergo a blood test for any reason. A patient was considered seropositive after two consecutive positive results with two different kits (Abbott and DiaSorin).The overall seroprevalence was 3.8% (95%CI 3.7-4.0), males higher than females [4.9% (95%CI 4.6-5.2) vs. 3.1% (95%CI 2.9-3.3) respectively]. Adolescents had the highest prevalence [7.8% (95%CI 7.0-8.6)] compared to other age groups. Participants who had undergone RT-PCR testing had a tenfold higher risk to be seropositive. The prevalence-to-incidence ratio was 4.5-15.7. Serology testing is an important complimentary tool for assessing the actual magnitude of infection and thus essential for implementing policy measures to control the pandemic. A positive serology test result was recently accepted in Israel as being sufficient to define recovery, with possible far-reaching consequences, such as the deploying of employees to ensure the maintenance of a functional economy.

Real-world safety data for the Pfizer BNT162b2 SARS-CoV-2 vaccine: historical cohort study.

OBJECTIVE: The Pfizer BNT162b2 vaccine showed a reassuring safety profile in clinical trials, but real-world data are scarce. Bell's palsy, herpes zoster, Guillain-Barré syndrome (GBS) and other neurological complaints in proximity to vaccination have received special public attention. We compared their rates among vaccinated and unvaccinated individuals. METHODS: Individuals ≥16 years vaccinated with at least one dose of BNT162b2 were eligible for this historical cohort study in a health maintenance organization insuring 1.2 million citizens. Each vaccinee was matched to a non-vaccinated control by sex, age, population sector (general Jewish, Arab, ultra-orthodox Jewish) and comorbidities. Diagnosis of Covid-19 before or after vaccination was an exclusion criterion. The outcome was a diagnosis of Bell's palsy, GBS, herpes zoster or symptoms of numbness or tingling, coded in the visit diagnosis field using ICD-9 codes. Diagnoses of Bell's palsy and GBS were verified by individual file review. RESULTS: Of 406 148 individuals vaccinated during the study period, 394 609 (97.2%) were eligible (11 539 excluded). A total of 233 159 (59.1%) were matched with unvaccinated controls. Mean follow was 43 ± 15.14 days. In vaccinated and unvaccinated individuals there were 23 versus 24 cases of Bell's palsy (RR 0.96, CI 0.54-1.70), one versus zero cases of GBS, 151 versus 141 cases of herpes zoster (RR 1.07, CI 0.85-1.35) and 605 versus 497 cases of numbness or tingling (RR 1.22, CI 1.08-1.37), respectively. DISCUSSION: No association was found between vaccination, Bell's palsy, herpes zoster or GBS. Symptoms of numbness or tingling were more common among vaccinees. This study adds reassuring data regarding the safety of the BNT162b2 vaccine.

BNT162b2 Vaccine Effectiveness in Preventing Asymptomatic Infection With SARS-CoV-2 Virus: A Nationwide Historical Cohort Study.

BACKGROUND: There is strong evidence regarding the efficacy and effectiveness of the BNT162b2 vaccine in preventing symptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There is a relative paucity of data regarding its effectiveness in the prevention of asymptomatic infection. METHODS: In this real-world observational study, we identified a subpopulation of individuals in a large health maintenance organization who were repeatedly tested for SARS-CoV-2 infection by polymerase chain reaction (PCR). We included these individuals in the study cohort and compared those who were vaccinated with BNT162b2 mRNA vaccine to unvaccinated individuals. A positive SARS-CoV-2 PCR test result was used as the outcome. The follow-up period was from January 1, 2021, until February 11, 2021. RESULTS: A total of 6286 individuals were included in the cohort. Seven days after the second vaccine dose, a rate of 6 positive PCR tests per 10 000 person-days was recorded, compared with a rate of 53 positive tests per 10 000 person-days for the unvaccinated group. The estimated vaccine effectiveness against infection with SARS-CoV-2 virus after 2 vaccine doses was 89% (95% CI, 82%-94%). The estimated effectiveness 2 weeks after the first vaccine dose was 61% (95% CI, 49%-71%). CONCLUSIONS: In this study, vaccination with BNT162b2 reduced infection rates among individuals who underwent screening by frequent SARS-CoV-2 PCR testing. Using a cohort of frequently tested individuals reduced the indication bias for the PCR testing, which enabled estimation of infection rates.