Effectiveness of BNT162b2 Vaccine against Omicron Variant Infection among Children 5-11 Years of Age, Israel.

We assessed effectiveness of the BNT162b2 vaccine against infection with the B.1.1.529 (Omicron) variant (mostly BA.1 subvariant), among children 5-11 years of age in Israel. Using a matched case-control design, we matched SARS-CoV-2-positive children (cases) and SARS-CoV-2-negative children (controls) by age, sex, population group, socioeconomic status, and epidemiologic week. Vaccine effectiveness estimates after the second vaccine dose were 58.1% for days 8-14, 53.9% for days 15-21, 46.7% for days 22-28, 44.8% for days 29-35, and 39.5% for days 36-42. Sensitivity analyses by age group and period demonstrated similar results. Vaccine effectiveness against Omicron infection among children 5-11 years of age was lower than vaccine efficacy and vaccine effectiveness against non-Omicron variants, and effectiveness declined early and rapidly.

Vaccine coverage associated with ending a SARS-CoV-2 wave: a retrospective longitudinal analysis.

BACKGROUND: Two SARS-CoV-2 waves in Israel ended while a substantial number of individuals remained unvaccinated or partially vaccinated. The indirect protective effect of the first BNT162b2 vaccination campaign in Israel was evaluated between 22 December 2020 and 18 May 2021. METHODS: The daily percentage of new PCR-confirmed SARS-CoV-2 cases among unvaccinated individuals was analyzed for trends. Major shifts were identified using piecewise linear regression analysis. At these shifts, the percentage of naturally vaccinated (past SARS-CoV-2 cases) and the percentage of actively vaccinated (by inoculation) individuals were weighted and summed to determine the percentage of natural and active vaccination (NAV). RESULTS: A first decline among unvaccinated individuals occurred during a lockdown period, when the percentage of NAV was 8.16%. The major decline occurred after the end of the lockdown when the percentage of NAV reached 52.05%. SARS-CoV-2 cases ultimately declined among unvaccinated individuals when the percentage of NAV reached 63.55%. During the study period, the Alpha variant was prevalent and the use of non-pharmaceutical intervention, including social distancing, existed to varying degrees. CONCLUSIONS: The vaccination campaign played a major role in the decline of SARS-CoV-2 infection among unvaccinated individuals, leading to the end of the first 2021 SARS-CoV-2 wave (alpha variant) in Israel. The infection of unvaccinated individuals stopped when two thirds of the population were naturally or actively vaccinated. Any change in characteristics of the virus or the population can lead to a new outbreak.

The impact of SARS-CoV-2 on respiratory syndromic and sentinel surveillance in Israel, 2020: a new perspective on established systems.

BackgroundThe COVID-19 pandemic presented new challenges for the existing respiratory surveillance systems, and adaptations were implemented. Systematic assessment of the syndromic and sentinel surveillance platforms during the pandemic is essential for understanding the value of each platform in the context of an emerging pathogen with rapid global spread.AimWe aimed to evaluate systematically the performance of various respiratory syndromic surveillance platforms and the sentinel surveillance system in Israel from 1 January to 31 December 2020.MethodsWe compared the 2020 syndromic surveillance trends to those of the previous 3 years, using Poisson regression adjusted for overdispersion. To assess the performance of the sentinel clinic system as compared with the national SARS-CoV-2 repository, a cubic spline with 7 knots and 95% confidence intervals were applied to the sentinel network's weekly percentage of positive SARS-CoV-2 cases.ResultsSyndromic surveillance trends changed substantially during 2020, with a statistically significant reduction in the rates of visits to physicians and emergency departments to below previous years' levels. Morbidity patterns of the syndromic surveillance platforms were inconsistent with the progress of the pandemic, while the sentinel surveillance platform was found to reflect the national circulation of SARS-CoV-2 in the population.ConclusionOur findings reveal the robustness of the sentinel clinics platform for the surveillance of the main respiratory viruses during the pandemic and possibly beyond. The robustness of the sentinel clinics platform during 2020 supports its use in locations with insufficient resources for widespread testing of respiratory viruses.

Monitoring SARS-CoV-2 Activity with Sentinel Surveillance: Lessons Learned from the First Wave in Israel.

BACKGROUND: Guidelines for pandemic preparedness emphasize the role of sentinel and syndromic surveillance in monitoring pandemic spread. OBJECTIVES: To examine advantages and obstacles of utilizing a sentinel influenza surveillance system to monitor community severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) activity based on Israel's experience from mid-March to mid-May 2020. METHODS: Several modifications were applied to the influenza surveillance system. The clinical component relied mainly on pneumonia and upper respiratory infection (URI) consultations with primary care physicians as well as visits to emergency departments (ED) due to pneumonia. The virological data were based on nasopharyngeal swabs obtained from symptomatic patients who visited outpatient clinics. RESULTS: By week 12 of the pandemic, the crude and age-specific primary physician consultation rates due to URI and pneumonia declined below the expected level, reaching nadir that lasted from week 15 until week 20. Similarly, ED visits due to pneumonia were significantly lower than expected from weeks 14 and 15 to week 20. The virological surveillance started on week 13 with 6/253 of the swabs (2.3%) positive for SARS-CoV-2. There was a peak of 13/225 positive swabs on week 145.8%. During weeks 17-20, none of the swabs (47-97 per week) were positive for SARS-CoV-2. This trend was similar to national data. CONCLUSIONS: The virological component of the surveillance system showed the SARS-CoV-2 community spread, but had low sensitivity when virus activity was low. The clinical component, however, had no yield. Sentinel surveillance can assist in monitoring future novel pandemics and should be augmented in revised preparedness plans.

Effectiveness of BNT162b2 Vaccine Booster against SARS-CoV-2 Infection and Breakthrough Complications, Israel.

We estimated vaccine effectiveness (VE) of the BNT162b2 (Pfizer-BioNTech, https://www.pfizer.com) booster dose against SARS-CoV-2 infection and reduction of complications (hospitalization, severe disease, and death) among breakthrough cases in persons in Israel >16 years of age for <20 weeks. VE estimates reached 96.8% (95% CI 96.0%-97.5%) for persons 16-59 years of age and 93.1% (95% CI 91.8%-94.2%) for persons >60 years of age on week 3. VE estimates remained at these levels for 8 weeks in the 16-59 age group and 11 weeks in those >60. A slow decline followed, becoming more pronounced in the last 2-3 weeks of evaluation. Estimates in the last week of evaluation were 77.6% (95% CI 68.4%-84.2%) and 61.3% (52.5%-68.4%) for persons 16-59 years and >60 years, respectively. The more pronounced VE decline coincided with rapid increase in Omicron variant activity. Rate reduction of breakthrough complications remained moderate to high throughout the evaluation.

Myocarditis after BNT162b2 mRNA Vaccine against Covid-19 in Israel.

BACKGROUND: Approximately 5.1 million Israelis had been fully immunized against coronavirus disease 2019 (Covid-19) after receiving two doses of the BNT162b2 messenger RNA vaccine (Pfizer-BioNTech) by May 31, 2021. After early reports of myocarditis during adverse events monitoring, the Israeli Ministry of Health initiated active surveillance. METHODS: We retrospectively reviewed data obtained from December 20, 2020, to May 31, 2021, regarding all cases of myocarditis and categorized the information using the Brighton Collaboration definition. We analyzed the occurrence of myocarditis by computing the risk difference for the comparison of the incidence after the first and second vaccine doses (21 days apart); by calculating the standardized incidence ratio of the observed-to-expected incidence within 21 days after the first dose and 30 days after the second dose, independent of certainty of diagnosis; and by calculating the rate ratio 30 days after the second dose as compared with unvaccinated persons. RESULTS: Among 304 persons with symptoms of myocarditis, 21 had received an alternative diagnosis. Of the remaining 283 cases, 142 occurred after receipt of the BNT162b2 vaccine; of these cases, 136 diagnoses were definitive or probable. The clinical presentation was judged to be mild in 129 recipients (95%); one fulminant case was fatal. The overall risk difference between the first and second doses was 1.76 per 100,000 persons (95% confidence interval [CI], 1.33 to 2.19), with the largest difference among male recipients between the ages of 16 and 19 years (difference, 13.73 per 100,000 persons; 95% CI, 8.11 to 19.46). As compared with the expected incidence based on historical data, the standardized incidence ratio was 5.34 (95% CI, 4.48 to 6.40) and was highest after the second dose in male recipients between the ages of 16 and 19 years (13.60; 95% CI, 9.30 to 19.20). The rate ratio 30 days after the second vaccine dose in fully vaccinated recipients, as compared with unvaccinated persons, was 2.35 (95% CI, 1.10 to 5.02); the rate ratio was again highest in male recipients between the ages of 16 and 19 years (8.96; 95% CI, 4.50 to 17.83), with a ratio of 1 in 6637. CONCLUSIONS: The incidence of myocarditis, although low, increased after the receipt of the BNT162b2 vaccine, particularly after the second dose among young male recipients. The clinical presentation of myocarditis after vaccination was usually mild.

Effectiveness of BNT162b2 Vaccine in Adolescents during Outbreak of SARS-CoV-2 Delta Variant Infection, Israel, 2021.

In Israel, the BNT162b2 vaccine against severe acute respiratory syndrome coronavirus 2 was approved for use in adolescents in June 2021, shortly before an outbreak of B.1.617.2 (Delta) variant-dominant infection. We evaluated short-term vaccine effectiveness and found the vaccine to be highly effective among this population in this setting.

The BNT162b2 vaccine effectiveness against new COVID-19 cases and complications of breakthrough cases: A nation-wide retrospective longitudinal multiple cohort analysis using individualised data.

BACKGROUND: The rapid vaccination campaign against COVID-19 in Israel relied on the BNT162b2 vaccine. We performed a longitudinal analysis of multiple cohorts, using individual data, to evaluate the effectiveness of the vaccine against new and breakthrough cases. METHODS: We estimated vaccine effectiveness (VE) for 27 consecutive cohorts, each comprised of individuals vaccinated on specific days. VE against new COVID-19 cases was evaluated for five SARS-CoV-2-related outcomes: infection, symptomatic disease, hospitalisation, severe/critical disease and death. For breakthrough cases, rate reduction was evaluated for hospitalisation, severe/critical disease and death. Outcomes were evaluated at predetermined time-periods after vaccination, the last one dedicated to individuals who became SARS-CoV-2-positive 22-28 days after the second dose. FINDINGS: The highest VE estimates against new cases in ≥16 year old individuals, for all outcomes, were reached at the 15-21 day period after the second dose, ranging between 97.7% (95% CI: 95.9-98.7%) for deaths and 98.6% (95% CI: 97.8-99.1%) for severe/critical disease. VE estimates of the 14-20 day period after the first dose ranged between 54.3% (95% CI: 50.6-57.8%) for infection and 77.3% (95% CI: 71.2-82.1%) for severe/critical disease. VE rose more slowly among ≥80 year old individuals. Rate reductions of breakthrough complications were highest at the 22-28 day period after the second dose, ranging between 47.4% (95% CI: 4.3-71.2%) for death and 66.2% (95% CI: 44.2-79.6%) for severe/critical disease. INTERPRETATION: The BNT162 vaccine is highly effective in preventing new SARS-CoV-2 cases. Among ≥80 year old individuals, high effectiveness develops more slowly. In breakthrough cases, vaccination reduces complications and death. FUNDING: None.

A COVID-19 call center for healthcare providers: dealing with rapidly evolving health policy guidelines.

BACKGROUND: Communication between health authorities and healthcare providers is an essential element of the response to public health emergencies. Although call centers can facilitate such communication, no published reports describing their outcomes exist. In advance of the expected COVID-19 outbreak in Israel, the Israel Center for Disease Control established a call center dedicated to queries from healthcare professionals. METHODS: The call center operated from February 5, 2020 (week 6) to May 14, 2020 (week 20). Data on calls received, including date and time, caller characteristics, questions and responses were recorded in a database designed for this purpose. The volume, sources and content of queries were analyzed. RESULTS: In 15 weeks of operation, the call center responded to 6623 calls. The daily number of calls ranged from 1 to 371 (mean 79.8, median 40), peaking on week 12, 2 weeks prior to a peak in new COVID-19 cases. Callers were predominantly physicians (62.4%), nurses (18.7%) and administrators (4.4%). Most worked in primary care clinics (74.2%) or hospitals (8.7%). Among physicians, 42.3% were family physicians or internists, and 10.0% were pediatricians. The issues most commonly addressed were home quarantine (21.6%), criteria for suspected cases (20.6%), and SARS-CoV2 testing (14.1%). Twenty-five percent of questions involved requests for clarifications of MOH guidelines regarding travel restrictions, clinic management, triage of symptomatic patients, routine medical and dental care, recommended precautions for health care workers with preexisting medical conditions, and other matters. A total of 119 queries were not resolved on the basis of existing guidelines and were referred to MOH headquarters. CONCLUSIONS: This is the first report of a call center established to serve the needs of healthcare providers seeking guidance on COVID-19 management, and to facilitate communication of providers' concerns to the central health authority. Our work indicates that a central call center for healthcare providers can facilitate the development, implementation and amendment of guidelines and should be an integral element of the early response to public health emergencies. Real-time analysis of the call data may reveal important trends requiring prompt attention.