Preliminary analysis of the epidemiological effectiveness of COVID-19 vaccination in the Saratov Region

The new coronavirus infection (COVID-19) caused by the SARS-CoV-2 virus continues to spread rapidly worldwide, despite the increased prevention and treatment measures being taken. Vaccination is one of the most cost-effective and effective methods of preventing infectious diseases in the modern world, including one of the most effective methods of combating COVID-19. Over several centuries of history, vaccination has proven its effectiveness in saving people's lives, reducing the spread of infectious diseases among the population, as well as reducing mortality. The effectiveness of immunization against COVID-19 is an urgent problem at the moment, especially when it comes to vaccination. The aim of the work is to study the effect of vaccination on the incidence of a new coronavirus infection among residents of the Saratov Region. Material and methods. Methods of retrospective epidemiological analysis of trends in the epidemic process COVID-19 were used. The obtained materials were processed using methods of variational statistics (Excel program). The analysis was based on data from daily monitoring of laboratory diagnostic results (more than 1780 thousand PCR diagnostic studies were conducted during the epidemic), COVID-19 cases and deaths, taking into account the coverage of the population with preventive vaccinations. The statistical significance of the differences was assessed according to the Student's criterion. The differences were considered significant at t<=2. Results and discussion. As of June 30, 2021, more than 267 thousand people or 11% of the population of the Saratov region were fully vaccinated against COVID-19. There were no complications after the introduction of vaccines. In the structure of all medical immunobiological preparations that were immunized, the proportion of the vaccine "Gam-COVID-Vac" was 97.88%, "Epivaccorona" - 1.69% and "Covivac" - 0.43%. According to preliminary data, 361 of the vaccinated people were infected with SARS-CoV-2, of which: 255 (70.6%) had a mild course of the disease with manifestations of catarrhal syndrome, 84 (23.3%) had community-acquired pneumonia, 22 (6%) had no symptoms of the disease. No deaths have been registered among the vaccinated. The overall incidence of COVID-19 among vaccinated was 0.06%. The incidence rate of COVID-19 among the vaccinated population is 6.025+/-0.15 per 10 thousand people, which is significantly lower (t>2) than among the unvaccinated (103.8+/-0.63 per 10 thousand people), efficiency index - 17.23, epidemiological efficiency coefficient - 94.20% Conclusion. Insufficient coverage of the population of the Saratov Region with vaccination (as of June 30, 2021, 11% were fully vaccinated) does not allow to influence the reduction of the incidence of COVID-19. The high epidemiological effectiveness of COVID-19 vaccination of the adult population with domestic vaccines, including people over 65 years of age, has been revealed.Copyright © 2022 Geotar Media Publishing Group

Projection of COVID-19 Positive Cases Considering Hybrid Immunity: Case Study in Tokyo.

Since the emergence of COVID-19, the forecasting of new daily positive cases and deaths has been one of the essential elements in policy setting and medical resource management worldwide. An essential factor in forecasting is the modeling of susceptible populations and vaccination effectiveness (VE) at the population level. Owing to the widespread viral transmission and wide vaccination campaign coverage, it becomes challenging to model the VE in an efficient and realistic manner, while also including hybrid immunity which is acquired through full vaccination combined with infection. Here, the VE model of hybrid immunity was developed based on an in vitro study and publicly available data. Computational replication of daily positive cases demonstrates a high consistency between the replicated and observed values when considering the effect of hybrid immunity. The estimated positive cases were relatively larger than the observed value without considering hybrid immunity. Replication of the daily positive cases and its comparison would provide useful information of immunity at the population level and thus serve as useful guidance for nationwide policy setting and vaccination strategies.

Effectiveness of vaccination with symptoms by age groups.

This paper examines effectiveness of vaccination with symptoms by age groups in the US and Hamamatsu city in Japan. The efficacy of vaccination has been reported in Singapore, but both datasets such as the US CDC dataset and the Hamamatsu dataset contradict the Singapore results. Both local government and government datasets are publicly available for peer review and reader validation.

Estimation of mRNA COVID-19 Vaccination Effectiveness in Tokyo for Omicron Variants BA.2 and BA.5: Effect of Social Behavior.

The variability of the COVID-19 vaccination effectiveness (VE) should be assessed with a resolution of a few days, assuming that the VE is influenced by public behavior and social activity. Here, the VE for the Omicron variants (BA.2 and BA.5) is numerically derived for Japan's population for the second and third vaccination doses. We then evaluated the daily VE variation due to social behavior from the daily data reports in Tokyo. The VE for the Omicron variants (BA.1, BA.2, and BA.5) are derived from the data of Japan and Tokyo with a computational approach. In addition, the effect of the different parameters regarding human behavior on VE was assessed using daily data in Tokyo. The individual VE for the Omicron BA.2 in Japan was 61% (95% CI: 57-65%) for the second dose of the vaccination from our computation, whereas that for the third dose was 86% (95% CI: 84-88%). The individual BA.5 VE for the second and third doses are 37% (95% CI: 33-40%) and 63% (95% CI: 61-65%). The reduction in the daily VE from the estimated value was closely correlated to the number of tweets related to social gatherings on Twitter. The number of tweets considered here would be one of the new candidates for VE evaluation and surveillance affecting the viral transmission.

COVID-19 forecasting using new viral variants and vaccination effectiveness models.

Recently, a high number of daily positive COVID-19 cases have been reported in regions with relatively high vaccination rates; hence, booster vaccination has become necessary. In addition, infections caused by the different variants and correlated factors have not been discussed in depth. With large variabilities and different co-factors, it is difficult to use conventional mathematical models to forecast the incidence of COVID-19. Machine learning based on long short-term memory was applied to forecasting the time series of new daily positive cases (DPC), serious cases, hospitalized cases, and deaths. Data acquired from regions with high rates of vaccination, such as Israel, were blended with the current data of other regions in Japan such that the effect of vaccination was considered in efficient manner. The protection provided by symptomatic infection was also considered in terms of the population effectiveness of vaccination as well as the vaccination protection waning effect and ratio and infectivity of different viral variants. To represent changes in public behavior, public mobility and interactions through social media were also included in the analysis. Comparing the observed and estimated new DPC in Tel Aviv, Israel, the parameters characterizing vaccination effectiveness and the waning protection from infection were well estimated; the vaccination effectiveness of the second dose after 5 months and the third dose after two weeks from infection by the delta variant were 0.24 and 0.95, respectively. Using the extracted parameters regarding vaccination effectiveness, DPC in three major prefectures of Japan were replicated. The key factor influencing the prevention of COVID-19 transmission is the vaccination effectiveness at the population level, which considers the waning protection from vaccination rather than the percentage of fully vaccinated people. The threshold of the efficiency at the population level was estimated as 0.3 in Tel Aviv and 0.4 in Tokyo, Osaka, and Aichi. Moreover, a weighting scheme associated with infectivity results in more accurate forecasting by the infectivity model of viral variants. Results indicate that vaccination effectiveness and infectivity of viral variants are important factors in future forecasting of DPC. Moreover, this study demonstrate a feasible way to project the effect of vaccination using data obtained from other country.

Preliminary analysis of the epidemiological effectiveness of COVID-19 vaccination in the Saratov Region

The new coronavirus infection (COVID-19) caused by the SARS-CoV-2 virus continues to spread rapidly worldwide, despite the increased prevention and treatment measures being taken. Vaccination is one of the most cost-effective and effective methods of preventing infectious diseases in the modern world, including one of the most effective methods of combating COVID-19. Over several centuries of history, vaccination has proven its effectiveness in saving people's lives, reducing the spread of infectious diseases among the population, as well as reducing mortality. The effectiveness of immunization against COVID-19 is an urgent problem at the moment, especially when it comes to vaccination. The aim of the work is to study the effect of vaccination on the incidence of a new coronavirus infection among residents of the Saratov Region. Material and methods. Methods of retrospective epidemiological analysis of trends in the epidemic process COVID-19 were used. The obtained materials were processed using methods of variational statistics (Excel program). The analysis was based on data from daily monitoring of laboratory diagnostic results (more than 1780 thousand PCR diagnostic studies were conducted during the epidemic), COVID-19 cases and deaths, taking into account the coverage of the population with preventive vaccinations. The statistical significance of the differences was assessed according to the Student's criterion. The differences were considered significant at t≤2. Results and discussion. As of June 30, 2021, more than 267 thousand people or 11% of the population of the Saratov region were fully vaccinated against COVID-19. There were no complications after the introduction of vaccines. In the structure of all medical immunobiological preparations that were immunized, the proportion of the vaccine “Gam-COVID-Vac” was 97.88%, “Epivaccorona” - 1.69% and “Covivac” - 0.43%. According to preliminary data, 361 of the vaccinated people were infected with SARS-CoV-2, of which: 255 (70.6%) had a mild course of the disease with manifestations of catarrhal syndrome, 84 (23.3%) had community-acquired pneumonia, 22 (6%) had no symptoms of the disease. No deaths have been registered among the vaccinated. The overall incidence of COVID-19 among vaccinated was 0.06%. The incidence rate of COVID-19 among the vaccinated population is 6.025±0.15 per 10 thousand people, which is significantly lower (t>2) than among the unvaccinated (103.8±0.63 per 10 thousand people), efficiency index - 17.23, epidemiological efficiency coefficient - 94.20% Conclusion. Insufficient coverage of the population of the Saratov Region with vaccination (as of June 30, 2021, 11% were fully vaccinated) does not allow to influence the reduction of the incidence of COVID-19. The high epidemiological effectiveness of COVID-19 vaccination of the adult population with domestic vaccines, including people over 65 years of age, has been revealed. © 2022 Geotar Media Publishing Group

Vaccine-induced and naturally-acquired protection against Omicron and Delta symptomatic infection and severe COVID-19 outcomes, France, December 2021 to January 2022.

We assessed the protection conferred by naturally-acquired, vaccine-induced and hybrid immunity during the concomitant Omicron and Delta epidemic waves in France on symptomatic infection and severe COVID-19. The greatest levels of protection against both variants were provided by hybrid immunity. Protection against Omicron symptomatic infections was systematically lower and waned at higher speed than against Delta in those vaccinated. In contrast, there were little differences in variant-specific protection against severe inpatient outcomes in symptomatic individuals.

Two waves of COIVD-19 in Brazilian cities and vaccination impact.

BACKGROUNDS: Brazil has suffered two waves of Coronavirus Disease 2019 (COVID-19). The second wave, coinciding with the spread of the Gamma variant, was more severe than the first wave. Studies have not yet reached a conclusion on some issues including the extent of reinfection, the infection fatality rate (IFR), the infection attack rate (IAR) and the effects of the vaccination campaign in Brazil, though it was reported that confirmed reinfection was at a low level. METHODS: We modify the classical Susceptible-Exposed-Infectious-Recovered (SEIR) model with additional class for severe cases, vaccination and time-varying transmission rates. We fit the model to the severe acute respiratory infection (SARI) deaths, which is a proxy of the COVID-19 deaths, in 20 Brazilian cities with the large number of death tolls. We evaluate the vaccination effect by a contrast of "with" vaccination actual scenario and "without" vaccination in a counterfactual scenario. We evaluate the model performance when the reinfection is absent in the model. RESULTS: In the 20 Brazilian cities, the model simulated death matched the reported deaths reasonably well. The effect of the vaccination varies across cities. The estimated median IFR is around 1.2%. CONCLUSION: Overall, through this modeling exercise, we conclude that the effects of vaccination campaigns vary across cites and the reinfection is not crucial for the second wave. The relatively high IFR could be due to the breakdown of medical system in many cities.

Multiple COVID-19 Waves and Vaccination Effectiveness in the United States.

(1) Background: The coronavirus 2019 (COVID-19) pandemic has caused multiple waves of cases and deaths in the United States (US). The wild strain, the Alpha variant (B.1.1.7) and the Delta variant (B.1.617.2) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were the principal culprits behind these waves. To mitigate the pandemic, the vaccination campaign was started in January 2021. While the vaccine efficacy is less than 1, breakthrough infections were reported. This work aims to examine the effects of the vaccination across 50 US states and the District of Columbia. (2) Methods: Based on the classic Susceptible-Exposed-Infectious-Recovered (SEIR) model, we add a delay class between infectious and death, a death class and a vaccinated class. We compare two special cases of our new model to simulate the effects of the vaccination. The first case expounds the vaccinated individuals with full protection or not, compared to the second case where all vaccinated individuals have the same level of protection. (3) Results: Through fitting the two approaches to reported COVID-19 deaths in all 50 US states and the District of Columbia, we found that these two approaches are equivalent. We calculate that the death toll could be 1.67-3.33 fold in most states if the vaccine was not available. The median and mean infection fatality ratio are estimated to be approximately 0.6 and 0.7%. (4) Conclusions: The two approaches we compared were equivalent in evaluating the effectiveness of the vaccination campaign in the US. In addition, the effect of the vaccination campaign was significant, with a large number of deaths averted.

Assessment of the benefits of seasonal influenza vaccination: Elements of a framework to interpret estimates of vaccine effectiveness and support robust decision-making and communication.

Systematic reviews and meta-analyses confirm that influenza vaccination reduces the risk of influenza illness by between about 40% and 60% in seasons when circulating influenza stains are well matched to vaccine strains. Influenza vaccine effectiveness (IVE) estimates, however, are often discordant and a source of confusion for decision makers. IVE assessments are increasingly publicized and are often used by policy makers to make decisions about the value of seasonal influenza vaccination. But there is limited guidance on how IVE should be interpreted or used to inform policy. There are several limitations to the use of IVE for decision-making: (a) IVE studies have methodological issues that often complicate the interpretation of their value; and (b) the full impact of vaccination will almost always be greater than the impact assessed by a point estimate of IVE in specific populations or settings. Understanding the strengths and weaknesses of study methodologies and the fundamental limitations of IVE estimates is important for the accuracy of interpretations and support of policy makers' decisions. Here, we review a comprehensive set of issues that need to be considered when interpreting IVE and determining the full benefits of influenza vaccination. We propose that published IVE values should be assessed using an evaluative framework that includes influenza-specific outcomes, types of VE study design, and confounders, among other factors. Better interpretation of IVE will improve the broader assessment of the value of influenza vaccination and ultimately optimize the public health benefits in seasonal influenza vaccination.