Edward Ramsay’s research while affiliated with Saint-Petersburg Institute of History and other places

Influenza infection represents a serious challenge for virological surveillance and healthcare systems in all countries globally. Despite obvious success in control of influenza through vaccination and antiviral drug development, this infection remains poorly controlled due to antigenic drift and fast selection of drug‐resistant viral variants. The design of novel drugs with alternative targets and mechanisms of action is, therefore, an important goal for medical science worldwide. In the current study, we describe the chemical synthesis of novel tetrahydro‐β‐carboline derivatives containing a thiohydantoin fragment, as well as their antiviral activity against influenza virus A/Puerto Rico/8/34 (H1N1). In general, the library of compounds was of low toxicity. Of the 23 compounds under investigation, 10 (43.5%) displayed a selectivity index (SI) of 10 or higher, their activity strongly exceeding that of the reference compound rimantadine. The most active compounds have also demonstrated suppressing activity against the phylogenetically distinct influenza virus of type B. These compounds, similar to the reference compound zanamivir, were active at very late stages of the viral cycle (4–6 h postinfection), suggesting interference with processes of virion assembly and budding. However, no direct inhibiting activity against viral neuraminidase has been demonstrated. The results obtained can be considered as a rationale for further structural optimization and study of this group as potential broad‐range antivirals effective against influenza viruses.

Specific prevention of measles, mumps, and rubella (MMR) is the main prerequisite for a radical reduction in the incidence of these infections in the Kyrgyz Republic (KR). An increase in the number of seronegative individuals observed in recent years has led to an increase in measles incidence. This is directly related to a decrease in collective immunity, which provides protection for the population only in conditions of a high density of immunized individuals and their uniform distribution in the population. The only way to estimate the number of immunized individuals is by conducting serological surveys of collective immunity. Aim of the study: The aim was to study the level of collective immunity to the MMR viruses in the KR. Materials and methods: This study involved a cohort of 6617 residents (volunteers) aged 1 to 70+ years, formed in accordance with the Rospotrebnadzor program “Assessment of collective immunity to vaccine-preventable and other relevant infections” and stratified by age and region of residence. During the study, participants filled out a questionnaire and gave venous blood samples to determine IgG antibodies to MMR viruses (ELISA using certified Russian test systems). Results: In December 2023, collective immunity ensured epidemiological well-being only with respect to rubella. The volunteer seropositivity was 94.2% (95% CI: 93.7–94.8). The average measles seropositivity was 78.9% (95% CI: 77.9–79.9). It was significantly lower in children aged 1–17 years and significantly higher than the cohort average in individuals aged ≥18 years. The average mumps seropositivity was 76.4% (95% CI: 75.3–77.4), with the minimum level noted among individuals aged 12–29 years (63.8%; 95% CI: 61.4–66.2). The maximum levels of mumps seropositivity were noted among children aged 6–11 years and older adults who had likely experienced mumps (50–70+ years). Seroprevalence distributions by activity correlated with age distributions (all infections). Conclusions: The system of targeted prophylaxis of vaccine-preventable infections adopted in the KR has contributed to the formation of a high level of rubella collective immunity and, to a lesser extent, measles and mumps immunity. The recent trend towards increases in measles and mumps incidence in the KR requires additional efforts to increase collective immunity to these infections.

The severity of MeV infection has been greatly reduced by the development of a live attenuated vaccine, which has been incorporated into vaccination programs in many countries. However, poor access to health facilities, and above all, the increase in anti-vaccination movements, has prevented the achievement of sufficient vaccination coverage. In outbreak scenarios, a rapid and transportable method can improve differential diagnosis, including removing ambiguity in suspected measles cases, contacts, or a cohort. In response to the need, we have developed a new RT-qPCR-based MeV detection assay. The LOD of the developed assay was determined on different PCR machines and the higher threshold was 1–1.2 10³ copies/mL. The joint diagnostic sensitivity of ELISA and RT-PCR (used together) was 100%, and used combinedly, these two methods enable detection of all measles-infected persons, which is extremely important for controlling contagion and spread of infection. During the clinical validation of the assay on 200 clinical samples from measles-suspected cases using ELISA, 157 samples showed a positive result, while 163 positive cases were confirmed by the RT-qPCR assay. The concordance between the two techniques was 93%. According to our results, the real-time RT-PCR approach used in our study is more sensitive and appears to be a more promising method for measles diagnosis during early stages of the disease, likely before the rise of specific IgM antibodies detected by ELISA.

Russia is a country with a high incidence of tick-borne encephalitis (TBE). In northwestern regions of Russia, 110 TBE cases were registered in 2021. The largest numbers of TBE cases were registered in the Arkhangelsk region and St. Petersburg. TBEV seropositivity among healthy individuals, including the unvaccinated population in northwestern Russia, was found in 12.2% of studied samples, indicating active TBEV circulation. The prevalence of TBEV is 2.4% in the two tick species most common in northwestern regions of Russia, Ixodes ricinus and Ixodes persulcatus. However, there is still no comprehensive data on the molecular characterization and phylogenetic analysis of the circulating TBEV strains. The purpose of the study was to determine the prevalence of TBEV and to identify its subtypes in ixodid ticks collected in specific areas of northwestern Russian regions. Phylogenetic analysis of E protein sequences of ten obtained strains showed that they all belong to the Siberian subtype, which were clustered into two groups: the most numerous Baltic group, clusteron 3D; and the Vasilchenko group. However, some unique isolates may form new clusterons.

Specific measles, mumps, and rubella prevention has been the main prerequisite for a striking decline in the incidence of such infections in Russia. An increase in the percentage of seronegative individuals observed in recent years resulted in higher measles incidence being directly related to low herd immunity that accounts for a population protection solely under conditions of a high density of immunized individuals and their uniform distribution in the population. The number of immunized individuals may be estimated only while conducting seroepidemiological monitoring of herd immunity. Objective of the study: to assess a level of herd immunity in the St. Petersburg and Leningrad Region population against measles, mumps, and rubella viruses. Materials and methods. There were enrolled 6,774 residents into the study: volunteers aged from 1 to 70+ years. The representativeness of the surveyed cohort was ensured by using the Web application "Monitoring of herd immunity against socially significant infections", used at the stage of volunteer enrollment, by randomization and regulation of the sample size in age groups. Participants filled out a questionnaire and agreed to provide venous blood samples to assess IgG antibody levels against measles, mumps, and rubella viruses by using ELISA. Results. In September 2023, in St. Petersburg and the Leningrad Region, herd immunity met the criterion for epidemiological well-being only with respect to rubella. In all age groups, the proportion of seronegative individuals did not exceed 15%, and most volunteers had high Ab levels, both after illness and vaccination. For measles and mumps, the criterion for epidemiological well-being is considered not to exceed more than 7% seronegative individuals. A sufficient level of measles seroprevalence was detected only in older age groups (≥60 years old). Sufficient mumps seroprevalence was not detected in any age group. The average population (St. Petersburg, Leningrad Region) seroprevalence magnitude for measles, rubella, and mumps viruses were 81.4%, 95.5%, and 78.4%, respectively. The problematic age groups with low measles seroprevalence (62.4–74.3%) were adolescents (12-17 yrs) and young adults (18-39 yrs). Most seropositive individuals vaccinated against measles had low Ab levels; high levels were noted mainly in older measles convalescent individuals. Low mumps seroprevalence (~70%) was more often observed among adults aged 18 to 49 years. The distribution of seroprevalence in various occupational group was relatively uniform, with some predominance of seropositivity among pensioners and schoolchildren. Conclusion. The system of specific prophylaxis for vaccine-preventable viral infections used in Russia has shown high efficacy and contributed to the formation of herd immunity, which for many years allowed to lower a risk of both sporadic and group infections to minimal levels. Currently, measles and mumps seroprevalence in the local population is maintained at insufficient level to ensure epidemiological well-being. This necessitates making appropriate management decisions and conducting additional preventive measures aimed at enhancing relevant herd immunity.

Purpose of the study: to study the dynamics of developing herd immunity against SARS-CoV-2 in the population of the Republic of Kyrgyzstan during COVID-19. Materials and methods. The work was carried out using the methodology for assessing population immunity developed by Rospotrebnadzor (Russia) as well as the Ministry of Health (Kypgyzstan) and the St. Petersburg Pasteur Institute. The selection of participants was carried out by questionnaire using a cloud (Internet server) service. To monitor population immunity, a cohort of 2421 subjects was formed, who participated in all stages of seromonitoring. Volunteers were randomized according to age groups (1–17, 18–29, 30–39, 40–49, 50–59, 60–69, 70+ years), regional and professional factors. Antibodies (Abs) against SARS-CoV-2 nucleocapsid (Nc) and the receptor binding domain (RBD) of S-glycoprotein were determined by qualitative and quantitative methods. The study was carried out in 3 stages according to a single scheme: 1st stage — 06/28–07/03/2021, 2nd — 21–25/02/2022 and 3rd — 31/10–04/11/2022. Since 2021, Kyrgyzstan has been vaccinating the population against SARS-CoV-2 mainly using inactivated whole-virion vaccines. Results. Population immunity against SARS-CoV-2 was predominantly accounted for by both Ab types (Nc+RBD+). By the 3rd stage, the percentage of such persons reached 99.2%, Nc–RBD– volunteers — up to 0.8%. At the 1st stage, middle-aged people dominated, but age differences were leveled out by the 2nd stage. The greatest impact on seroprevalence was found among medical workers, the smallest — among businessmen and industrial workers. Populational vaccination significantly impacted on the state of herd immunity that reached 25% by the 3rd stage. The refusals of the population in Kyrgyz Republic from vaccination noted at the 2nd and especially 3rd stages did not significantly affect level of herd immunity, which could probably be associated with asymptomatic cases of COVID-19, against which primary vaccination had a booster effect. Conclusion. The dynamics of population humoral immunity against SARS-CoV-2 included a number of changes in the level of circulating antibodies (Nc, RBD), caused by both primary infection and vaccination. The herd immunity formed in population of Kyrgyzstan allowed to reduce the incidence of COVID-19 to almost sporadic level.

Background Since its beginnings in 2019, the COVID-19 pandemic is still a problem of global medical concern. Southern Vietnam is one of the country's vast regions, including 20 provinces and the densely populated metropolis Ho Chi Minh City. A randomized retrospective study was performed to investigate the epidemiology and genetic diversity of COVID-19. Whole-genome sequencing of 126 SARS-CoV-2 samples collected from Southern Vietnam between January 2020 and December 2021 revealed the main circulating variants and their distribution. Methods Epidemiological data were obtained from the Department of Preventive Medicine of the Vietnamese Ministry of Health. To identify circulating variants, RNA, extracted from 126 nasopharyngeal swabs of patients with suspected COVID-19 were sequenced on Illunina MiSeq to obtain near complete genomes SARS-CoV-2. Results Due to the effectiveness of restrictive measures in Vietnam, it was possible to keep incidence at a low level. The partial relaxation of restrictive measures, and the spread of Delta lineages, contributed to the beginning of a logarithmic increase in incidence. Lineages 20A-H circulated in Southern Vietnam during 2020. Spread of the Delta lineage in Southern Vietnam began in March 2021, causing a logarithmic rise in the number of COVID-19 cases. Conclusions Pandemic dynamics in Southern Vietnam feature specific variations in incidence, and these reflect the success of the restrictive measures put in place during the early stages of the pandemic.

Introduction: The COVID-19 pandemic has become a serious challenge for humanity almost everywhere globally. Despite active vaccination around the world, the incidence proportion in different countries varies significantly as of May 2022. The reason may be a combination of demographic, immunological, and epidemiological factors. The purpose of this study was to analyze possible relationships between COVID-19 incidence proportion in the population and the types of SARS-CoV-2 vaccines used in different countries globally, taking into account demographic and epidemiological factors. Materials and methods: An initial database was created of demographic and immunoepidemiological information about the COVID-19 situation in 104 countries collected from published official sources and repository data. The baseline included, for each country, population size and density; SARS-CoV-2 testing coverage; vaccination coverage; incidence proportion; and a list of vaccines that were used, including their relative share among all vaccinations. Subsequently, the initial data set was stratified by population and vaccination coverage. The final data set was subjected to statistical processing both in general and taking into account population testing coverage. Results: After formation of the final data set (including 53 countries), it turned out that reported COVID-19 case numbers correlated most strongly with testing coverage and the proportions of vaccine types used, specifically, mRNA (V1); vector (V2); peptide/protein (V3); and whole-virion/inactivated (V4). Due to the fact that an inverse correlation was found between 'reported COVID-19 case numbers' with V2, V3, and V4, these three vaccine types were also combined into one analytic group, 'non-mRNA group' vaccines (Vnmg). When the relationship between vaccine type and incidence proportion was examined, minimum incidence proportion was noted at V1:Vnmg ratios (%:%) from 0:100 to 30:70. Maximum incidence proportion was seen with V1:Vnmg from 80:20 to 100:0. On the other hand, we have shown that the number of reported COVID-19 cases in different countries largely depends on testing coverage. To offset this factor, countries with low and extremely high levels of testing were excluded from the data set; it was then confirmed that the largest number of reported COVID-19 cases occurred in countries with a dominance of V1 vaccines. The fewest reported cases were seen in countries with a dominance of Vnmg vaccines. Conclusion: In this paper, we have shown for the first time that the level of reported COVID-19 incidence proportion depends not only on SARS-CoV-2 testing and vaccination coverage, which is quite logical, but probably also on the vaccine types used. With the same vaccination level and testing coverage, those countries that predominantly use vector and whole-virion vaccines feature incidence proportion that is significantly lower than countries that predominantly use mRNA vaccines.