Predictors of reinfection with pre-Omicron and Omicron variants of concern among individuals who recovered from COVID-19 in the first year of the pandemic

OBJECTIVES

The predictors of SARS-CoV-2 reinfection are unclear. We examined predictors of reinfection with pre-Omicron and Omicron variants among COVID-19-recovered individuals.

METHODS

Randomly selected COVID-19-recovered patients (N=1004) who donated convalescent plasma during 2020 were interviewed between August 2021-March 2022 regarding COVID-19 vaccination and laboratory-proven reinfection. Sera from 224 (22.3%) participants were tested for anti-S (spike) IgG and neutralizing antibodies.

RESULTS

The participants' median age was 31.1 years (78.6% males). The overall reinfection incidence rate was 12.8%; 2.7% vs. 21.6% for the pre-Omicron (mostly Delta) vs. Omicron variants. Negative associations were found between fever during the first illness and pre-Omicron reinfection: relative risk (RR) 0.29 (95% confidence intervals (CI) 0.09-0.94); high anti-N level at first illness and Omicron reinfection: 0.53 (0.33-0.85), and overall reinfection: 0.56 (0.37-0.84), as well as between subsequent COVID-19 vaccination with the BNT162b2 vaccine and pre-Omicron 0.15 (0.07-0.32), Omicron 0.48 (0.25-0.45), and overall reinfections 0.38 (0.25-0.58). These variables significantly correlated with IgG anti-S follow-up levels. High pre-existing anti-S binding and neutralizing antibody levels against SARS-CoV-2 Wuhan and Alpha strains predicted protection against Omicron reinfections.

CONCLUSIONS

Strong immune responses following first COVID-19 infection and subsequent vaccination with the BNT162b2 vaccine provided cross-protection against reinfections with Delta and Omicron variants.

Sero-Prevalence and Sero-Incidence of Antibodies to SARS-CoV-2 in Health Care Workers in Israel, Prior to Mass COVID-19 Vaccination

Objectives: This study aims to examine the prevalence and risk factors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sero-positivity in health care workers (HCWs), a main risk group, and assess the sero-incidence of SARS-CoV-2 infection between the first and second waves of coronavirus disease 2019 (COVID-19) in Israel. Methods: A longitudinal study was conducted among 874 HCWs from nine hospitals. Demographics, health information, and blood samples were obtained at baseline (first wave-April-May 2020) and at follow-up (n = 373) (second wave-September-November 2020). Sero-positivity was determined based on the detection of total antibodies to the nucleocapsid antigen of SARS-CoV-2, using electro-chemiluminescence immunoassay (Elecsys® Anti-SARS-CoV-2, Roche Diagnostics, Rotkreuz, Switzerland). Results: The sero-prevalence of SARS-CoV-2 antibodies was 1.1% [95% confidence intervals (CI) 0.6-2.1] at baseline and 8.3% (95% CI 5.9-11.6) at follow-up. The sero-conversion of SARS-CoV-2 serum antibody was 6.9% (95% CI 4.7-9.9) during the study period. The increase in SARS-CoV-2 sero-prevalence paralleled the rise in PCR-confirmed SARS-CoV-2 infections among the HCWs across the country. The likelihood of SARS-CoV-2 sero-prevalence was higher in males vs. females [odds ratio (OR) 2.52 (95% CI 1.05-6.06)] and in nurses vs. physicians [OR 4.26 (95% CI 1.08-16.77)] and was associated with being quarantined due to exposure to COVID-19 patients [OR 3.54 (95% CI 1.58-7.89)] and having a positive PCR result [OR 109.5 (95% CI 23.88-502.12)]. Conclusions: A significant increase in the risk of SARS-CoV-2 infection was found among HCWs between the first and second waves of COVID-19 in Israel. Nonetheless, the sero-prevalence of SARS-CoV-2 antibodies remains low, similar to the general population. Our findings reinforce the rigorous infection control policy, including quarantine, and utilization of personal protective equipment that should be continued together with COVID-19 immunization in HCWs and the general population.

Diagnostic medical auxiliary equipment in a field hospital: experience from the Israeli delegation to the site of the Turkish earthquake at Adapazari

An earthquake striking a highly populated area is likely to cause a mass casualty situation for even the most advanced trauma center. If the local medical teams are injured and the hospitals are damaged beyond immediate repair, external intervention is needed. In the Turkish earthquake crisis, Israel was one of many states to deploy a field hospital to the crisis site. This was set up in Adapazari, the second most severely hit city in terms of the amount of damage. The hospital provided advanced surgical and medical facilities, including laparotomy, cesarean section, and intensive care surveillance. These facilities require sophisticated laboratory and radiology services, including hematology, chemistry, microbiology, and blood bank. The speed with which the hospital must be assembled and transported to be efficient and the basic conditions of a field hospital dictate specific considerations regarding diagnostic auxiliary equipment. Considerations in choosing this equipment, problems encountered during installation, and recommendations for the future are presented.

Prevalence of antibodies to West Nile fever, sandfly fever Sicilian, and sandfly fever Naples viruses in healthy adults in Israel

BACKGROUND

The arbovirus infections West Nile fever (WNF) and sandfly fever (SFF) are both endemic in the Middle East. Despite the fact that the mosquito and sandfly vectors of these viruses are still found in Israel, SFF has not been reported since 1948, whereas outbreaks of WNF occur periodically. It is suspected that some of the cases of nonspecific febrile illnesses in Israel may in fact be either WNF or SFF.

AIM

To determine the extent of past arbovirus infections in subgroups of Israeli soldiers.

METHODS

Sera from random samples of three groups of healthy soldiers aged 18-20 (n=273), 21-30 (n=497), and 40-55 years (n=285) were examined for IgG and IgM antibodies to West Nile virus (WNV), sandfly fever Sicilian virus (SFSV), and sandfly fever Naples virus (SFNV), using an ELISA method.

RESULTS

The prevalence of antibodies increased with age for all three viruses examined, and ranged from 7.0%, 0, and 2.8%, for WNV, SFSV, AND SFNV, respectively, in soldiers aged 18-20 years, to 41.9%, 23.7%, and 30.8%, in those aged 40-55 years. The percentage of seropositives for IgG who were also IgM positive were 1.0%, 5.9%, and 3.4%, for WNV, SFSV, AND SFNV, respectively. 17.5% of the seropositives for WNV were also positive for SFSV, as compared with 5.7% among the WNV-seronegatives. Among the seropositives for WNV, 23.99% were positive for SFNV, compared with 9.1% of WNV seronegatives. 48.2% of seropositives for SFSV were positive for SFNV, as compared with 8.4% for SFSV-seronegatives. In the age agroup 40-55 years, there were significantly higher prevalence rates in those born in Israel compared with those born abroad.

CONCLUSIONS

There is still significant exposure to WNV, SFSV, and SFNV in Israel. Arborviruses are probably responsible for many cases of non-specific febrile illness in this region.