Rapid molecular epidemiology investigations into two recent measles outbreaks in Israel detected from October 2023 to January 2024.

Between late 2023 and early 2024, two measles outbreaks occurred in Israel, each caused by importation of measles virus strains of respective B3 and D8 genotypes. In this study, we validate transmission pathways uncovered by epidemiological investigations using a rapid molecular approach, based on complete measles virus genomes. The presented findings support this rapid molecular approach in complementing conventional contact tracing and highlight its potential for informing public health interventions.

Measles outbreak associated with a preschool setting among partially vaccinated children in the Tel Aviv District, Israel, October 2023.

In October 2023, the Tel Aviv District was notified of ten cases of measles. The outbreak initiated in a preschool with high vaccination coverage with one dose of MMR vaccine. Serological testing was available for eight patients (six children and two adults). Among the six children vaccinated with one dose of MMR vaccine, primary vaccine failure was demonstrated. Among the adults, secondary vaccine failure was confirmed. The outbreak was successfully contained due to a combination of factors, notably its occurrence within a population characterized by high vaccination coverage in Tel Aviv, during a period of restricted public interactions due to the prevailing state of war in the country. Despite challenging wartime conditions, effective prophylactic measures were promptly executed, encompassing a 2-dose MMR vaccination schedule for close contacts and the broader community of children in the TA district, successfully curbing the outbreak and preventing widespread infections.

Does the SARS-CoV-2 mRNA vaccine and its serum IgG levels affect fertility treatments and obstetric outcomes? An observational cohort study.

BACKGROUND: Although there are some data regarding the COVID-19 vaccine and in in vitro fertilization (IVF) treatments, its potential impact in terms of serum immunoglobulin G (IgG) levels has not been evaluated prospectively. This study aimed to assess the effect of COVID-19 vaccine and IgG levels on IVF outcomes. METHODS: This observational, cohort study was conducted at a referral IVF unit. Couples undergoing IVF treatment during the COVID-19 vaccination period were recruited from March-April 2021. The study compared 38 women who had received the Pfizer mRNA COVID-19 vaccination to 10 women who had not and were not infected by the virus. We also compared pre- and post-vaccination IVF treatments for 24 women. The relation between serologic titers and IVF treatment outcomes was also assessed. RESULTS: No significant difference was found between the vaccinated and unvaccinated/uninfected groups regarding the main outcome measures. However, there was a trend toward a higher pregnancy rate for the unvaccinated group (57% vs. 23%, p = 0.078) but no difference in delivery rate (p = 0.236), gestational week (p = 0.537) or birth rate (p = 0.671). CONCLUSION: We cautiously state that the COVID-19 mRNA vaccine does not affect fertility outcomes, including fertilization, pregnancy and delivery rates, obstetric outcomes, and semen parameters, regardless of measured IgG levels.

SARS-CoV-2 IgG Levels as Predictors of XBB Variant Neutralization, Israel, 2022- and 2023.

Although a vaccine against SARS-CoV-2 Omicron-XBB.1.5 variant is available worldwide and recent infection is protective, the lack of recorded infection data highlights the need to assess variant-specific antibody neutralization levels. We analyzed IgG levels against receptor-binding domain-specific SARS-CoV-2 ancestral strain as a correlate for high neutralizing titers against XBB variants.

Humoral Immunity of Unvaccinated COVID-19 Recovered vs. Naïve BNT162b2 Vaccinated Individuals: A Prospective Longitudinal Study.

To study the differences in the immune response to SARS-CoV-2 infection compared to the response to vaccination, we characterized the humoral immune kinetics of these situations. In this prospective longitudinal study, we followed unvaccinated COVID-19-recovered individuals (n = 130) and naïve, two-dose BNT162b2-vaccinated individuals (n = 372) who were age- and BMI-matched for six months during the first pandemic year. Anti-RBD-IgG, neutralizing antibodies (NAbs), and avidity were assessed monthly. For recovered patients, data on symptoms and the severity of the disease were collected. Anti-RBD-IgG and NAbs titers at peak were higher after vaccination vs. after infection, but the decline was steeper (peak log IgG: 3.08 vs. 1.81, peak log NAbs: 5.93 vs. 5.04, slopes: -0.54 vs. -0.26). Peak anti-RBD-IgG and NAbs were higher in recovered individuals with BMI > 30 and in older individuals compared to individuals with BMI < 30, younger population. Of the recovered, 42 (36%) experienced long-COVID symptoms. Avidity was initially higher in vaccinated individuals compared with recovered individuals, though with time, it increased in recovered individuals but not among vaccinated individuals. Here, we show that while the initial antibody titers, neutralization, and avidity are lower in SARS-CoV-2-recovered individuals, they persist for a longer duration. These results suggest differential protection against COVID-19 in recovered-unvaccinated vs. naïve-vaccinated individuals.

Factors Associated With Protection From SARS-CoV-2 Omicron Variant Infection and Disease Among Vaccinated Health Care Workers in Israel.

Importance: A correlation between antibody levels and risk of infection has been demonstrated for the wild-type, Alpha, and Delta SARS-COV-2 variants. High rates of breakthrough infections by the Omicron variant emphasized the need to investigate whether the humoral response elicited by mRNA vaccines is also associated with reduced risk of Omicron infection and disease. Objective: To investigate whether the high antibody levels in individuals who have received at least 3 doses of an mRNA vaccine are associated with reduced risk of Omicron infection and disease. Design, Setting, and Participants: This prospective cohort study used serial real time-polymerase chain reaction (RT-PCR) and serological test data from January and May 2022 to assess the association of preinfection immunoglobin G (IgG) and neutralizing antibody titers with incidence of Omicron variant infection, incidence of symptomatic disease, and infectivity. Participants included health care workers who had received 3 or 4 doses of an mRNA COVID-19 vaccine. Data were analyzed from May to August 2022. Exposures: Levels of SARS-CoV-2 anti-receptor binding domain IgG and neutralizing antibodies. Main Outcomes and Measures: The main outcomes were incidence of Omicron infection, incidence of symptomatic disease, and infectivity. Outcomes were measured using SARS-COV-2 PCR and antigen testing and daily online surveys regarding symptomatic disease. Results: This study included 3 cohorts for 3 different analyses: 2310 participants were included in the protection from infection analysis (4689 exposure events; median [IQR] age, 50 [40-60] years; 3590 [76.6%] among female health care workers), 667 participants (median [IQR] age, 46.28 (37.44,54.8); 516 [77.4%] female) in the symptomatic disease analysis, and 532 participants (median [IQR] age, 48 [39-56] years; 403 [75.8%] female) in the infectivity analysis. Lower odds of infection were observed for each 10-fold increase in preinfection IgG (odds ratio [OR], 0.71; 95% CI, 0.56-0.90) and for each 2-fold increase in neutralizing antibody titers (OR, 0.89; 95% CI, 0.83-0.95). The odds of substantial symptomatic disease were reduced for each 10-fold increase in IgG levels (OR, 0.48; 95% CI, 0.29-0.78) and for each 2-fold increase in neutralizing antibodies levels (OR, 0.86; 95% CI, 0.76-0.96). Infectivity, assessed by mean cycle threshold value, was not significantly decreased with increasing IgG or neutralizing antibodies titers. Conclusions and Relevance: In this cohort study of vaccinated health care workers, IgG and neutralizing antibody titer levels were associated with protection against infection with the Omicron variant and against symptomatic disease.

Correlates of protection against COVID-19 infection and intensity of symptomatic disease in vaccinated individuals exposed to SARS-CoV-2 in households in Israel (ICoFS): a prospective cohort study.

BACKGROUND: Identifying COVID-19 correlates of protection and immunity thresholds is important for policy makers and vaccine development. We aimed to identify correlates of protection of BNT162b2 (Pfizer-BioNTech) vaccination against COVID-19. METHODS: In this prospective cohort study, households within a radius of 40 km of the Sheba Medical Center in Israel in which a new SARS-CoV-2 infection (defined as the index case) was detected within the previous 24 h were approached between July 25 and Nov 15, 2021. We included adults (aged >18 years) who had received one or two vaccine doses, had an initial negative SARS-CoV-2 PCR and no previous infection reported, and had a valid IgG and neutralising antibody result. The exposure of interest was baseline immune status, including IgG antibody concentration, neutralising antibody titre, and T-cell activation. The outcomes of interest were PCR-positive SARS-CoV-2 infection between day 2 and day 21 of follow-up and intensity of disease symptoms (self-reported via a telephone questionnaire) among participants who had a confirmed infection. Multivariable logistic and ordered logit ordinal regressions were used for the adjusted analysis. To identify immunological thresholds for clinical protection, we estimated the conditional probability of infection and moderate or severe disease for individuals with pre-exposure IgG and neutralising antibody concentrations above each value observed in the study data. FINDINGS: From 16 675 detected index cases in the study region, 5718 household members agreed to participate, 1461 of whom were eligible to be included in our study. 333 (22·8%) of 1461 household members who were not infected with SARS-CoV-2 at baseline were infected within 21 days of follow-up. The baseline (pre-exposure) IgG and neutralising antibodies were higher in participants who remained uninfected than in those who became infected (geometric mean IgG antibody concentration 168·2 binding antibody units [BAU] per mL [95% CI 158·3-178·7] vs 130·5 BAU/mL [118·3-143·8] and geometric mean neutralising antibody titre 197·5 [181·9-214·4] vs 136 ·7 [120·3-155·4]). Increasing IgG and neutralising antibody concentrations were also significantly associated with a reduced probability of increasing disease severity. Odds of infection were significantly reduced each time baseline IgG antibody concentration increased by a factor of ten (odds ratio [OR] 0·43 [95% CI 0·26-0·70]) and each time baseline neutralising antibody titre increased by a factor of two (0·82 [0·74-0·92]). In our cohort, the probability of infection if IgG antibody concentrations were higher than 500 BAU/mL was 11% and the probability of moderate disease severity was 1%; the probability of infection if neutralising antibody titres were above or equal to 1024 was 8% and the probability of moderate disease severity was 2%. T-cell activation rates were not significantly associated with reduced probability of infection (OR 1·04, 95% CI 0·83-1·30). INTERPRETATION: Both IgG and neutralising antibodies are correlates of protection against SARS-CoV-2 infection. Our data suggest that IgG concentrations higher than 500 BAU/mL and neutralising antibody titres of 1024 or more are thresholds for immunological protection from SARS-CoV-2 delta variant infection. Potentially, updated protective thresholds against emerging variants of concern could be calculated, which could support decision makers on administration of new vaccination strategies and on the optimal period between vaccine doses. FUNDING: Israeli Ministry of Health.

Immunogenicity of Omicron BA.1-adapted BNT162b2 vaccines: randomized trial, 3-month follow-up.

OBJECTIVES: The capability of the SARS-CoV-2 Omicron variant to escape immunity conferred by mRNA vaccines has led to the development of Omicron-adapted vaccines. In this study, we aimed to compare the immune response with the ancestral strain and with the BA.1 Omicron variant after administration of the original vaccine and the Omicron-adapted vaccine. METHODS: This is an ongoing phase 3, double-blinded randomized controlled trial, comparing the original BNT161b2 vaccine, monovalent Omicron BA.1-adapted BNT161b2 vaccine, and bivalent combinations. Each vaccine was given at a 30 µg and 60 µg dose. Primary outcomes considered included neutralization titers of SARS-CoV-2 ancestral strain and Omicron BA.1. Exploratory endpoints included neutralization titers for Omicron BA.5, and the incidence of COVID-19 cases. RESULTS: Overall, 122 individuals (22, 19, 20, 20, 20, 20, and 21 in each arm) completed a 90-day follow-up. Three months after vaccination, adjusting for baseline levels, neutralizing antibody titers were 0.63 (95% CI: 0.3-1.32) and 0.54 (0.24-1.2) for monovalent/60 µg, 0.9 (0.42-1.92) and 2.69 (1.17-6.17) times for monovalent-Omi.BA.1/30 µg, 1.28 (0.6-2.75) and 2.79 (1.21-6.41) times for monovalent-Omi.BA.1/60 µg, 0.96 (0.46-1.97) and 2.07 (0.93-4.58) times for bivalent-Omi.BA.1/30 µg, and 0.79 (0.38-1.63) and 1.95 (0.88-4.32) times for bivalent-Omi.BA.1/60 µg when compared with BNT162b2/30 µg against the ancestral strain and BA.1 variant, respectively. DISCUSSION: BA.1-adapted mRNA vaccines lead to a stronger neutralizing antibody response against the Omicron BA.1 sub-variant.

Reduced Neutralization Efficacy against Omicron Variant after Third Boost of BNT162b2 Vaccine among Liver Transplant Recipients.

The immune responses of liver transplant (LT) recipients after the third boost of the BNT162b2mRNA vaccine improved. This study evaluates the durability of the immune response of LT recipients after the third boost, its predictors, and the impact of emerging variants. The receptor-binding domain IgG was determined at median times of 22 (first test) and 133 days (second test) after the administration of the third boost. IgG antibody titers > 21.4 BAU/mL were defined as a positive response. The neutralization efficacies of the vaccine against the wild-type, Omicron, and Delta variants were compared in the first test. The 59 LT recipients were of a median age of 61 years (range 25−82); 53.5% were male. Following administration of the third dose, the positive immune response decreased from 81.4% to 76.3% between the first and second tests, respectively, (p < 0.0001). The multivariate analysis identified CNI monotherapy (p = 0.02) and hemoglobin > 12 g/dL (p = 0.02) as independent predictors of a maintained positive immune response 133 days after the third dose. The geometric mean titers of Omicron neutralization were significantly lower than the wild-type and Delta virus (21, 137, 128, respectively; p < 0.0001). The immune response after the third BNT162b2mRNA vaccine dose decreased significantly in LT recipients. Further studies are required to evaluate the efficacy of the fourth vaccine dose and the durability of the immune response.

Humoral Response to the Fourth BNT162b2 Vaccination and Link Between the Fourth Dose, Omicron Infection, and Disease Severity in Renal Transplant Recipients.

BACKGROUND: The effectiveness of the fourth BNT162b2 vaccination in reducing the rate and severity of coronavirus disease 2019 (COVID-19) caused by the Omicron variant in renal transplant recipients (RTRs) is unknown. METHODS: Interviews were conducted with 447 RTRs regarding the status and timing of the fourth vaccination, prior vaccinations, and preceding COVID-19 infection. RTRs with polymerase chain reaction-confirmed COVID-19 infection from December 1, 2021, to the end of March 2022 were considered to have been infected with the Omicron variant and were interviewed to determine their disease severity. In a subgroup of 74 RTRs, the humoral response to the fourth dose was analyzed. In 30 RTRs, microneutralization assays were performed to reveal the humoral response to wild-type, Delta, and Omicron variant isolates before and after the fourth dose. RESULTS: Of 447 RTRs, 144 (32.2%) were infected with the Omicron variant, with 71 (49.3%) of the infected RTRs having received the fourth vaccine dose. RTRs who did not receive the fourth dose before the infection had more serious illness. In a subgroup of 74 RTRs, the fourth dose elicited a positive humoral response in 94.6% (70/74), with a significant increase in geometric mean titer for receptor-binding domain immunoglobulin G and neutralizing antibodies ( P < 0.001). The humoral responses to the Omicron variant before and after the fourth dose were significantly lower than the responses to the wild-type and the Delta variants. CONCLUSIONS: Overall, the fourth BNT162b2 dose was effective in reducing the rate and severity of Omicron disease in RTRs, despite the reduced humoral response to the variant.

High Immune Response Rate to the Fourth Boost of the BNT162b2 Vaccine against the Omicron Variants of Concern among Liver Transplant Recipients.

The immune response of liver transplant (LT) recipients to a third dose of the BNT162b2 mRNA vaccine significantly waned after four months. We aimed to evaluate the immune response and breakthrough infection rates of a fourth dose against the Omicron variants among LT recipients. LT recipients who had no past or active SARS-CoV-2 infection and received three doses of the BNT162b2mRNA vaccine were included. Of the 73 LT recipients, 50 (68.5%) received a fourth dose. The fourth dose was associated with a significantly higher positive immune response than the third dose. Receptor-binding domain (RBD) IgG and Omicron BA.1 and BA.2 neutralizing antibodies were determined at a median of 132 and 29 days after the third and fourth vaccines. They were 345 binding antibody units per milliliter (BAU/mL) vs. 2118 BAU/mL (p < 0.0001), 10 vs. 87 (p < 0.0001), and 15 vs. 149 (p = 0.001), respectively. Breakthrough infections were documented among nine (18%) LT recipients after the fourth dose and among seven (30.4%) patients following the third dose (p = 0.2); 93.5% of breakthrough infections were mild. The infection rate after the fourth dose was higher among diabetic vs. nondiabetic recipients (33.3% vs. 6.9%, respectively; p = 0.02). Further studies are needed to evaluate additional factors influencing the breakthrough infection rate among LT recipients.

Immunogenicity and efficacy of fourth BNT162b2 and mRNA1273 COVID-19 vaccine doses; three months follow-up.

Booster doses for the ongoing COVID-19 pandemic are under consideration in many countries. We report a three-month follow-up of 700 participants in a fourth vaccine dose study, comparing BNT162b2 and mRNA1273, administered four months after a third BNT162b2 dose. The primary outcomes are the levels of IgG, neutralizing antibodies, and microneutralization and the secondary outcomes are the levels of IgA and T cell activation, and clinical outcomes of SARS-CoV-2 infection and substantial symptomatic disease. Waning of the immune response is evident during follow-up, with an 11% (ß = 0.89, 95% CI, 0.88-0.9) and 21% (ß = 0.79, 95% CI, 0.76-0.82) multiplicative decay per week of IgG and neutralizing antibodies, respectively, in the mRNA1273 group, and of 14% (ß = 0.86, 95% CI, 0.86-0.87) and 26% (ß = 0.74, 95% CI, 0.72-0.76), respectively, in the BNT162b2 group. Direct neutralization of Omicron variants is low relative to ancestral strains. Cumulatively over the study period, both vaccines show little efficacy against infection but were highly efficacious against substantial symptomatic disease [89% [(IRR 0.11, 95% CI, 0.02-0.37) and 71% (IRR 0.29, 95% CI, 0.13-0.57) for mRNA1273 and BNT162b2, respectively]. These results are informative for further boosting policy-making. Trial registration numbers (clinicaltrials.gov): NCT05231005 and NCT05230953.

Real-World Immunogenicity and Reactogenicity of Two Doses of Pfizer-BioNTech COVID-19 Vaccination in Children Aged 5-11 Years.

There are limited data concerning the immunogenicity and reactogenicity of COVID-19 vaccines in children. A total of 110 children, 5-11 years old were vaccinated with two doses (with a 3-week interval between doses) of the Pfizer-BioNTech COVID-19 vaccine and were followed for 21, 90, and 180 days after vaccination for immunogenicity, adverse events, and breakthrough infections. Ninety days after the first vaccine dose, the GeoMean (CI 95%) of IgG ascended to 1291.0 BAU (929.6-1790.2) for uninfected children and 1670.0 BAU (1131.0-2466.0) for Infected children. One hundred and eighty days after receiving the first dose of the vaccine, the titers decreased to 535.5 BAU (288.4-993.6) for the uninfected children, while only a small decline was detected among infected children-1479.0 (878.2-2490.0). The neutralizing antibodies titer almost did not change over time in the uninfected children, and even elevated for the infected children. Of the 110 vaccinated children, 75.5% were infected, with only mild COVID-19 infection symptoms. Child vaccination was found to be safe, with mild, mostly local, and of short duration, reported AEs. No serious adverse events (SAEs) were reported after vaccination. The durability of two doses of vaccine in children is longer, thus a booster may not be needed as early as in adults.

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.

Durability of Immune Response After COVID-19 Booster Vaccination and Association With COVID-19 Omicron Infection.

Importance: The BNT162b2 two-dose vaccine (BioNTech/Pfizer) has high effectiveness that wanes within several months. The third dose is effective in mounting a significant immune response, but its durability is unknown. Objective: To compare antibody waning after second and third doses and estimate the association of antibody kinetics with susceptibility to infection with the Omicron variant of SARS-CoV-2. Design, Setting, and Participants: In a prospective longitudinal cohort study in a tertiary medical center in Israel, health care workers who received the BNT162b2 vaccine were followed up monthly for IgG and neutralizing antibody levels. Linear mixed models were used to compare antibody titer waning of second and third doses and to assess whether antibody dynamics were associated with Omicron transmission. Avidity, T cell activation, and microneutralization of sera against different variants of concern were assessed for a subgroup. Exposure: Vaccination with a booster dose of the BNT162b2 vaccine. Main Outcomes and Measures: The primary outcome was the rate of antibody titer change over time, and the secondary outcome was SARS-CoV-2 Omicron variant infection, as confirmed by reverse transcriptase-polymerase chain reaction. Results: Overall, 4868 health care workers (mean [SD] age, 46.9 [13.7] years; 3558 [73.1%] women) and 3972 health care workers (mean [SD] age, 48.5 [14.1] years; 996 [74.9%] women) were followed up for 5 months after their second and third vaccine doses, respectively. Waning of IgG levels was slower after the third compared with the second dose (1.32%/d [95% CI, 1,29%/d to 1.36%/d] vs 2.26% [95% CI, 2.13%/d 2.38%/d]), as was waning of neutralizing antibody levels (1.32%/d [95% CI, 1.21%/d to 1.43%/d] vs 3.34%/d [95% CI, 3.11%/d to 3.58%/d]). Among 2865 health care workers assessed for Omicron incidence during an additional 2 months of follow-up, lower IgG peak (ratio of means 0.86 [95% CI, 0.80-0.91]) was associated with Omicron infection, and among participants aged 65 years and older, faster waning of IgG and neutralizing antibodies (ratio of mean rates, 1.40; [95% CI, 1.13-1.68] and 3.58 [95% CI, 1.92-6.67], respectively) were associated with Omicron infection. No waning in IgG avidity was observed 112 days after the third dose. Live neutralization of Omicron was lower compared with previous strains, with a geometric mean titer at the peak of 111 (95% CI, 75-166), compared with 942 (95% CI, 585-1518) for WT, 410 (95% CI, 266-634) for Delta; it demonstrated similar waning to 26 (95% CI, 16-42) within 4 months. Among 77 participants tested for T cell activity, mean (SD) T cell activity decreased from 98 (5.4) T cells/106 peripheral blood mononuclear cells to 59 (9.3) T cells/106 peripheral blood mononuclear cells. Conclusions and Relevance: This study found that the third vaccine dose was associated with greater durability than the second dose; however, Omicron was associated with greater resistance to neutralization than wild type and Delta variants of concern. Humoral response dynamics were associated with susceptibility to Omicron infection.

Correlation between Adverse Events and Antibody Titers among Healthcare Workers Vaccinated with BNT162b2 mRNA COVID-19 Vaccine.

Objectives: The BNT162b2 mRNA COVID-19 vaccine has been found to be highly effective in preventing COVID-19 but is associated with increased reactogenicity. We aimed to examine the correlation between immunogenicity and reactogenicity of the BNT162b2 vaccine. Methods: Subjects without prior SARS-CoV-2 infection that participated in active surveillance after being vaccinated with the BNT162b2 vaccine were included. Study participants reported adverse drug reactions (ADRs) through questionnaires administered by text message after receiving each dose of the vaccine. A reactogenicity score was developed based on the type and duration of ADRs. In addition, anti-receptor binding domain (RBD) levels and neutralization assays were performed 7−21 and 7−38 days after the first and second vaccine doses, respectively. Associations between ADRs and antibody levels were assessed by Spearman correlations. Multivariable logistic regression analyses were used to identify factors associated with ADRs. Results: A total of 831 health care workers were included. The mean age was 46.5 years (SD = 11.8) and 75.5% were females. 83.4% and 83.3% had at least one local ADR after the first and second doses, respectively. 33% and 83.2% had at least one systemic ADR after the first and second doses, respectively. Multivariate logistic regression analysis found a significant correlation between ADR score and anti-RBD-IgG titers (r = 0.366; p < 0.0001) after adjustment for age, gender, and days after the second vaccination. High anti-RBD-IgG levels, being younger than 55 and being female, were all correlated with increased rates of ADRs. Conclusion: BNT162b2 mRNA COVID-19 vaccine reactogenicity appears to be correlated with higher post-vaccination antibody levels and is independently associated with younger age and female gender.

The Concordance between Mumps and Rubella Sero-Positivity among the Israeli Population in 2015.

Mumps and rubella are vaccine-preventable viral diseases through the measles-mumps-rubella-varicella (MMRV) vaccine, administered at 12 months and again at 6 years. We assessed the sero-prevalence of mumps and rubella, identified factors associated with sero-negativity, and evaluated concordance between mumps and rubella sero-positivity. A national cross-sectional sero-survey was conducted on samples collected in 2015 by the Israel National Sera Bank. Samples were tested for mumps and rubella IgG antibodies using an enzyme-linked immunosorbent assay. Of 3131 samples tested for mumps IgG, 84.8% (95%CI: 83.5-86.0%) were sero-positive. Sero-negativity for mumps was significantly associated with age (high odds ratios observed in infants younger than 4 years and 20-29 years old subjects). Of 3169 samples tested for rubella IgG antibodies, 95.2% (95%CI: 94.4-95.9%) were sero-positive. Rubella sero-negativity was significantly associated with age (high odds ratios observed in children younger than 4 years old and adults older than 30 years), males, Jews, and others. Concordant sero-positivity for both mumps and rubella viruses was observed in 83.9% of the tested samples. The Israeli population was sufficiently protected against rubella but not against mumps. Since both components are administered in the MMRV vaccine simultaneously, the mumps component has a lower uptake than rubella and quicker waning.