BCG and SARS-CoV-2-What Have We Learned?

Despite controversy over the protective effect of the BCG (Bacille Calmette-Guérin) vaccine in preventing pulmonary tuberculosis (TB) in adults, it has been used worldwide since 1921. Although the first reports in the 1930s had noted a remarkable decrease in child mortality after BCG immunization, this could not be explained solely by a decrease in mortality from TB. These observations gave rise to the suggestion of nonspecific beneficial effects of BCG vaccination, beyond the desired protection against M. tuberculosis. The existence of an innate immunity-training mechanism based on epigenetic changes was demonstrated several years ago. The emergence of the pandemic caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2) in 2019 revived the debate about whether the BCG vaccine can affect the immune response against the virus or other unrelated pathogens. Due to the mortality of the coronavirus disease (COVID-19), it is important to verify each factor that may have a potential protective value against the severe course of COVID-19, complications, and death. This paper reviews the results of numerous retrospective studies and prospective trials which shed light on the potential of a century-old vaccine to mitigate the pandemic impact of the new virus. It should be noted, however, that although there are numerous studies intending to verify the hypothesis that the BCG vaccine may have a beneficial effect on COVID-19, there is no definitive evidence on the efficacy of the BCG vaccine against SARS-CoV-2.

The Incidence of a New Coronavirus Infection in Medical Workers and the Evaluation of the Effectiveness of Individual Technologies for their Protection at Different Stages of the Pandemic

Relevance. The study of the incidence of medical workers with a new coronavirus infection during the COVID-19 pandemic is one of the topical areas of epidemiological research at this stage. The search for effective practices to reduce the incidence and risk of SARS-CoV-2 spread among employees of medical organizations is a promising area of research that is in demand in practice. Аim. Analysis of COVID-19 morbidity among health care staff during the pandemic and determination of the significance of selected specific and nonspecific prophylaxis measures in minimizing the risk of their occupational infection with SARS-CoV-2. Materials and methods. The reporting forms «General information about patients with positive COVID-19», «General information about patients with community-acquired pneumonia with positive COVID-19» (497 units of information), 2 176 cards of epidemiological investigation of cases of COVID-19 among employees of three municipalities were analyzed. We used epidemiological and statistical research methods. Conclusions. When analyzing the incidence of COVID-19 among employees of the medical worckers of the Khanty-Mansi autonomous оkrug – Yugra in the period from the 19th calendar week of 2020 to the 36th week of 2021, which corresponded to three epidemic rises, it was found that its level exceeded such in the unorganized adult population by 2.2 times, as well as the frequency of severe clinical forms of infection with lung damage. In the first two epidemic rises in the incidence, the highest incidence rate was recorded when the chances (OR) of getting COVID-19 among workers in the medical organizations compared to the adult population were the highest. In the first «wave» of the pandemic, they were 3.0, and in the second 2.6 times higher, as were the chances of developing clinical forms of COVID-19 with lung damage, which differed by 2.2 and 1.7 times, respectively, from those of an adult population (p<0.05). During the third epidemic rise, the situation changed radically. The incidence of new coronavirus infection in,medical worckers as well as the chances of getting sick, were equal to those in the adult population (OR 1.1), while the frequency of clinical forms of infection with lung involvement was even lower than in the population (P=95.7‰). The reason for the positive changes in the dynamics of the epidemic process was due to the formation among medical workers of a higher stratum of people protected from infection due to active, emergency vaccination and people with post-infection immunity as a result of infection in its various clinical forms than in the population. A detailed analysis of the incidence of COVID-19 in three medical organizations of Khanty-Mansiysk autonomous okrug-Yugra made it possible to obtain information that among employees of medical organizations vaccinated against a new coronavirus infection, the incidence of COVID-19 was 4.4 times lower than among those who were not vaccinated. In the cohort of those vaccinated, the frequency of clinical forms of the disease complicated by pneumonia was 4.7 times less, and the number of those hospitalized for inpatient treatment was 20.8 times lower. In medical workers who received a booster dose of the drug after vaccination, the incidence was 5.8 times lower compared to the unvaccinated cohort. Compared with the unvaccinated, there were 12.8 times fewer complicated clinical forms of the disease and 6.25 times the number of hospitalizations among them. A correlation was also found between the incidence of COVID-19 among employees of the medical workers and the area of premises per employee. Increasing the area of the premises per employee per 1 sq. m. led to a decrease in incidence by 2.1%. © 2022, Numikom. All rights reserved.

Vaccination With Oral Polio Vaccine Reduces COVID-19 Incidence.

Background: Effective response to emerging pandemic threats is complicated by the need to develop specific vaccines and other medical products. The availability of broadly specific countermeasures that could be deployed early in the pandemic could significantly alter its course and save countless lives. Live attenuated vaccines (LAVs) were shown to induce non-specific protection against a broad spectrum of off-target pathogens by stimulating innate immune responses. The purpose of this study was to evaluate the effect of immunization with bivalent Oral Poliovirus Vaccine (bOPV) on the incidence of COVID-19 and other acute respiratory infections (ARIs). Methods and Findings: A randomized parallel-group comparative study was conducted in Kirov Medical University. 1115 healthy volunteers aged 18 to 65 were randomized into two equal groups, one of which was immunized orally with a single dose of bOPV "BiVac Polio" and another with placebo. The study participants were monitored for three months for respiratory illnesses including COVID-19. The endpoint was the incidence of acute respiratory infections and laboratory confirmed COVID-19 in both groups during 3 months after immunization. The number of laboratory-confirmed cases of COVID-19 was significantly lower in the vaccinated group than in placebo (25 cases vs. 44, p=0.036). The difference between the overall number of clinically diagnosed respiratory illnesses in the two groups was not statistically significant. Conclusions: Immunization with bOPV reduced the number of laboratory-confirmed COVID-19 cases, consistent with the original hypothesis that LAVs induce non-specific protection against off-target infections. The findings are in line with previous observations of the protective effects of OPV against seasonal influenza and other viral and bacterial pathogens. The absence of a statistically significant effect on the total number of ARIs may be due to the insufficient number of participants and heterogeneous etiology of ARIs. OPV could be used to complement specific coronavirus vaccines, especially in regions of the world where the vaccines are unavailable, and as a stopgap measure for urgent response to future emerging infections. Clinical trial registration number NCT05083039 at clinicaltrals.gov https://clinicaltrials.gov/ct2/show/NCT05083039?term=NCT05083039&draw=2&rank=1.