Israel Medical Association Journal

Background: The 2019 severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic continued into 2020, and the coronavirus disease-2019 (COVID-19) associated death toll increased.

Objectives: To analyze COVID-19 death rates in European countries or regions to determine whether there was a significant association between bacillus Calmette-Guérin (BCG) vaccination policy and lower rates of COVID-19 related deaths.

Methods: Certain Northern European countries or regions had low death rates regardless of BCG policy. The authors assumed the consumption of foods containing salmiak (NH₄Cl) was a common and peculiar cause of the reduced COVID-19 related death rates in these countries, because NH₄Cl is a known lysosomotropic agent, which has been indicated to inhibit or prevent SARS-CoV infection. To check the possible effectiveness of salmiak consumption against COVID-19 related death, the authors used a linear regression model with the death rate as the dependent variable and BCG-policy and salmiak consumption score as independent variables.

Results: Using least squares regression and a robust standard error algorithm, the authors found a significant effect exerted by the independent variables (P < 0.0005 for BCG and P = 0.001 for salmiak). Salmiak score alone was significant (P = 0.016) when using least squares regression with robust error algorithm. 

Conclusions: The results seem to confirm an association between BCG-positive vaccination policy and salmiak consumption, and lower death rates from COVID-19. Implementing BCG vaccination policy and fortification of foods with salmiak (NH₄Cl) may have a significant impact on the control of SARS-CoV epidemic.

Background: Determining the accuracy of interferon gamma-releasing assays (IGRAs) is difficult due to the lack of a gold standard test for diagnosing latent tuberculosis (LTB). 

Objectives: To analyze the guidelines used for interpreting IGRAs in determining prophylactic treatment management for latent tuberculosis (LTB) in Israel.

Methods: We analyzed the retrospective data of 367 subjects who were referred to our laboratory during the period 2007–2011 for QuantiFERON Test-Gold In Tube (QFT-GIT) tests because of suspected LTB. Demographics and clinical data were retrieved from a questionnaire at enrollment, and 166/367 (45%) were further interviewed by phone in order to complete follow-up information on prophylactic TB treatment. 

Results: The majority of subjects (116/166, 69.9%, P < 0.0001) were spared prophylactic treatment subsequent to QFT-GIT testing. Subjects with negative QFT-GIT and positive tuberculin skin test (TST) results who were BCG-vaccinated had the lowest treatment rates (6/68, 8.8%, P < 0.0001). Most BCG-vaccinated subjects with positive TST and negative QFT-GIT test results received treatment with anti-tumor necrosis factor-alpha (TNFα) (17/19, 89.5%, P = 0.004). We found more negative QFT-GIT test results in subjects who were receiving anti-TNFα or steroid and other immunosuppressive treatment prior to testing (11/11, 100%, P = 0.029; 22/26, 84.6%, P = 0.06; 15/17, 88%, P = 0.06, respectively). 

Conclusions: Deciding on LTB prophylactic treatment in Israel is highly influenced by QFT-GIT test results. QFT-GIT findings contribute to clinical decisions, but their interpretation must also consider the patient’s medical history and clinical characteristics.