Estimated Infection and Vaccine Induced SARS-CoV-2 Seroprevalence in Israel among Adults, January 2020-July 2021.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) emerged in Israel in February 2020 and spread from then. In December 2020, the FDA approved an emergency use authorization of the Pfizer-BioNTech vaccine, and on 20 December, an immunization campaign began among adults in Israel. We characterized seropositivity for IgG anti-spike antibodies against SARS-CoV-2 between January 2020 and July 2021, before and after the introduction of the vaccine in Israel among adults. We tested 9520 serum samples, collected between January 2020 and July 2021. Between January and August 2020, seropositivity rates were lower than 5.0%; this rate increased from September 2020 (6.3%) to April 2021 (84.9%) and reached 79.1% in July 2021. Between January and December 2020, low socio-economic rank was an independent, significant correlate for seropositivity. Between January and July 2021, the 40.00-64.99-year-old age group, Jews and others, and residents of the Northern district were significantly more likely to be seropositive. Our findings indicate a slow, non-significant increase in the seropositivity rate to SARS-CoV-2 between January and December 2020. Following the introduction of the Pfizer-BioNTech vaccine in Israel, a significant increase in seropositivity was observed from January until April 2021, with stable rates thereafter, up to July 2021.

Under-diagnosis of SARS-CoV-2 infections among children aged 0-15 years, a nationwide seroprevalence study, Israel, January 2020 to March 2021.

Until recently, children and adolescents were not eligible for COVID-19 vaccination. They may have been a considerable source of SARS-CoV-2 spread. We evaluated SARS-CoV-2 IgG antibody seroprevalence in Israeli children aged 0-15 years from January 2020 to March 2021. Seropositivity was 1.8-5.5 times higher than COVID-19 incidence rates based on PCR testing. We found that SARS-CoV-2 infection among children is more prevalent than previously thought and emphasise the importance of seroprevalence studies to accurately estimate exposure.

Inferring Numbers of Wild Poliovirus Excretors Using Quantitative Environmental Surveillance.

Response to and monitoring of viral outbreaks can be efficiently focused when rapid, quantitative, kinetic information provides the location and the number of infected individuals. Environmental surveillance traditionally provides information on location of populations with contagious, infected individuals since infectious poliovirus is excreted whether infections are asymptomatic or symptomatic. Here, we describe development of rapid (1 week turnaround time, TAT), quantitative RT-PCR of poliovirus RNA extracted directly from concentrated environmental surveillance samples to infer the number of infected individuals excreting poliovirus. The quantitation method was validated using data from vaccination with bivalent oral polio vaccine (bOPV). The method was then applied to infer the weekly number of excreters in a large, sustained, asymptomatic outbreak of wild type 1 poliovirus in Israel (2013) in a population where >90% of the individuals received three doses of inactivated polio vaccine (IPV). Evidence-based intervention strategies were based on the short TAT for direct quantitative detection. Furthermore, a TAT shorter than the duration of poliovirus excretion allowed resampling of infected individuals. Finally, the method documented absence of infections after successful intervention of the asymptomatic outbreak. The methodologies described here can be applied to outbreaks of other excreted viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), where there are (1) significant numbers of asymptomatic infections; (2) long incubation times during which infectious virus is excreted; and (3) limited resources, facilities, and manpower that restrict the number of individuals who can be tested and re-tested.

A Significant Decrease in the Incidence of Shigellosis in Israel during COVID-19 Pandemic.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes COVID-19 and is mostly person-to-person transmitted through respiratory droplets. The implications of the strategies implemented to prevent COVID-19 transmission on other infectious diseases are unclear. We aimed to appraise trends in the incidence of salmonellosis, shigellosis and campylobacteriosis in Israel during COVID-19 pandemic. Positive stool samples for Salmonella, Shigella and Campylobacter are reported on a monthly basis to the Israel Center for Disease Control from sentinel laboratories, within the framework of a surveillance network of bacterial culture-proven enteric diseases. Age-adjusted incidence rates per 100,000 of shigellosis, salmonellosis and campylobacteriosis were calculated. Mean rates before and after the local onset of COVID-19 pandemic in Israel were compared and Relative Risk Reduction (RRR) was calculated. Joinpoint was used to evaluate secular trends. The mean age-adjusted incidence rate of shigellosis in March-July 2020 was lower than the rate observed in March-July 2018-2019 (RRR = 86.6%), but also decreased for salmonellosis (RRR = 33.0%) and campylobacteriosis (RRR = 30.0%). Using Joinpoint we have shown that the decrease observed for shigellosis was significantly sharper (Annual Percent Change (APC) = -77.7) between February 2020 and May 2020 than for salmonellosis (APC = -14.0) between July 2019 and April 2020 and for campylobacteriosis (APC = -1.1) between January 2018 and July 2020. The preventive measures applied to reduce transmission of COVID-19, including social distancing and hand washing, were ecologically associated with a decreased risk of bacterial enteric diseases in Israel. The association was strongest for shigellosis, a disease that is mostly person-to-person transmitted, as compared to salmonellosis and campylobacteriosis which are mostly foodborne transmitted.

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.

Multi-center nationwide comparison of seven serology assays reveals a SARS-CoV-2 non-responding seronegative subpopulation.

BACKGROUND: An Israeli national taskforce performed a multi-center clinical and analytical validation of seven serology assays to determine their utility and limitations for SARS-CoV-2 diagnosis. METHODS: Serology assays from Roche, Abbott, Diasorin, BioMerieux, Beckman-Coulter, Siemens, and an in-house RBD ELISA were included. Negative samples from 2391 individuals representative of the Israeli population, and 698 SARS-CoV-2 PCR positive patients, collected between March and May 2020, were analyzed. FINDINGS: Immunoassays sensitivities between 81.5%-89.4% and specificities between 97.7%-100% resulted in a profound impact on the expected Positive Predictive Value (PPV) in low (<15%) prevalence scenarios. No meaningful increase was detected in the false positive rate in children compared to adults. A positive correlation between disease severity and antibody titers, and no decrease in antibody titers in the first 8 weeks after PCR positivity was observed. We identified a subgroup of symptomatic SARS-CoV-2 positive patients (~5% of patients), who remained seronegative across a wide range of antigens, isotypes, and technologies. INTERPRETATION: The commercially available automated immunoassays exhibit significant differences in performance and expected PPV in low prevalence scenarios. The low false-positivity rate in under 20's suggests that cross-reactive immunity from previous CoV strains is unlikely to explain the milder disease course in children. Finding no decrease in antibody titers in the first 8 weeks is in contrast to some reports of short half-life for SARS-CoV-2 antibodies. The ~5% who were seronegative non-responders, using multiple assays in a population-wide manner, represents the proportion of patients that may be at risk for re-infection. FUNDING: Israel Ministry of Health.