Effectiveness of the CoronaVac® vaccine in a region of the Colombian Amazon, was herd immunity achieved?

Introduction Currently, more than 4.5 billion doses of SARS-CoV-2 vaccines have been applied worldwide. However, some developing countries are still a long way from achieving herd immunity through vaccination. In some territories, such as the Colombian Amazon, mass immunization strategies have been implemented with the CoronaVac® vaccine. Due to its proximity to Brazil, where one of the variants of interest of SARS-CoV-2 circulates. Objective To determine the effectiveness of the CoronaVac® vaccine in a population of the Colombian Amazon. Methods Between February 24, 2021, and August 10, 2021, a descriptive observational study was carried out in which a population of individuals over 18 years of age immunized with two doses of the CoronaVac® vaccine was evaluated. The study site was in the municipality of Mitú, Vaupés, in southeastern Colombia, a region located in the Amazon bordering Brazil. Results. 99% of the urban population of the Mitú municipality were vaccinated with CoronaVac®. To date, 5.7% of vaccinated individuals have become ill, and only 0.1% of these require hospitalization. One death was attributable to COVID-19 has been reported among vaccinated individuals, and the vaccine has shown 94.3% effectiveness against mild disease and 99.9% against severe infection. Conclusions The herd immunity achieved through mass vaccination in this population has made it possible to reduce the rate of complicated cases and mortality from COVID-19 in this region of the Colombian Amazon. Highlights CoronaVac® has shown 94.3% effectiveness against mild disease and 99.9% against severe infection in this indigenous population. CoronaVac® reduces the mortality rate from 2.2% in 2020 to 0.22% in 2021. The herd immunity was achieved through mass vaccination in this region of the Colombian Amazon.

Preventive Efficacy of Pneumococcal Conjugated Vaccine (Population Aspects)

Relevance. Pneumococcal disease remains an urgent public health problem, despite mass immunization of infants and young children. The impact of children’s universal vaccination on the morbidity and etiological structure in various clinical forms of infection remains unclear in children and adults. Аim. Тo evaluate the herd effect of children’s mass immunization with a 13-valent conjugated pneumococcal vaccine. Materials and Methods. The prophylactic efficacy of mass vaccination is studied within comparative retrospective epidemiological analysis of incidence rates and etiological structure of bacterial meningitis, ear diseases and mastoiditis, and community-acquired pneumonia in children and adults of Krasnoyarsk region in the pre- and post-vaccination periods, according to the official statistics and microbiological monitoring. Results. The changes in decrease of incidence rates with all clinical forms of pneumococcal infection except community-acquired pneumonia are revealed both in children and adults during mass immunization. Etiological structure changes and also changes of S. pneumoniae serotype distribution are detected in major clinical forms of infection. Conclusion. Reducing the incidence rates in children is determined predominantly by vaccinal prevention. The observed decrease of incidence rates in adults is the result of reducing the number of pneumococcal infection sources among children (herd immunity).

Waning of mRNA-1273 vaccine effectiveness against SARS-CoV-2 infection in Qatar

BACKGROUND: In early 2021, Qatar launched a mass immunization campaign with Moderna mRNA-1273 COVID-19 vaccine. We assessed persistence of real-world mRNA-1273 effectiveness against SARS-CoV-2 infection and against COVID-19 hospitalization and death. METHODS: Effectiveness was estimated using test-negative, case-control study design, between January 1 and December 5, 2021. Effectiveness was estimated against documented infection (a PCR-positive swab, regardless symptoms), and against any severe (acute-care hospitalization), critical (ICU hospitalization), or fatal COVID-19. RESULTS: By December 5, 2021, 2,962 breakthrough infections had been recorded among those who received two mRNA-1273 doses. Of these infections, 19 progressed to severe COVID-19 and 4 to critical, but none to fatal disease. mRNA-1273 effectiveness against infection was negligible for the first two weeks after the first dose, increased to 65.5% (95% CI: 62.7-68.0%) 14 or more days after the first dose, and reached its peak at about 90% in the first three months after the second dose. Effectiveness declined gradually starting from the fourth month after the second dose and was below 50% by the 7th month after the second dose. Effectiveness against severe, critical, or fatal COVID-19 reached its peak at essentially 100% right after the second dose, and there was no evidence for declining effectiveness over time. Effectiveness against symptomatic versus asymptomatic infection demonstrated the same pattern of waning, but effectiveness against symptomatic infection was consistently higher than that against asymptomatic infection and waned more slowly. CONCLUSIONS: mRNA-1273-induced protection against infection appears to wane month by month after the second dose. Meanwhile, protection against hospitalization and death appears robust with no evidence for waning for several months after the second dose.

Vaccination Against COVID-19: Emerging Issues and Future Prospects

The most effective means of combating the COVID-19 pandemic s the formation of herd immunity, with the formation of an immune population to infection. Vaccination rates are continuously increasing. In early February 2021, WHO announced that the number of people vaccinated against the disease for the first time exceeded the number of infected. In early June 2021 the vaccinated number exceeded 2 billion which is more than 12 times the total number infected for the entire duration of the pandemic. The high rate of vaccination leads to the formulation of a number of questions concerning the effectiveness of vaccines currently used for mass immunization the level of herd immunity, necessary to stop the spread of the disease, the actual duration of the vaccination carried out, long-term prospects of the platforms, used in the creation of vaccines. The purpose of this paper is to substantiate reasoned answers to the questions posed.

Students’ Views on Vaccination against COVID-19 Virus and Trust in Media Information about the Vaccine: The Case of Serbia

Mass immunization of the citizens of the Republic of Serbia began in January 2021. Information on the significance, manner, advantages and consequences of this process was intensively distributed through all communication channels, with the media playing a key role. According to the data of the official institutions for the public health of Serbia, by July 2021 the lowest percentage of vaccinated population was among those between the ages of 18 and 24—only 15% of this demographic had received the vaccine by this point. Given the low turnout of young people for vaccination, in this paper we investigated the general attitude of students in Serbia, as a special category of young people, towards the vaccine against the COVID-19 virus, as well as their attitude regarding information about vaccination in the media. Research was conducted on a sample of 345 students at the University of Novi Sad. The results of the research showed that 42% of students had not been vaccinated and did not plan to do so, 37.4% had received at least one dose of vaccine and 20.6% had not been vaccinated even though they planned to do so. Students who were vaccinated had more confidence in information provided through media channels than those who were not vaccinated. Therefore, it can be concluded that encouraging students to decide in favor of vaccination against the COVID-19 virus should come from the universities where they study as well as the media.

Safety and efficacy of RNA vaccines: State of the art

This review describes principles of action and the method of delivery of mRNA molecules into cells, as well as some of developed RNA vaccines and the results obtained in their study, though they have not been authorized for use yet. In addition, the review discusses efficacy and safety proved for RNA vaccines registered for COVID-19 prevention at the time of writing. The development, clinical trials and market launch of RNA vaccines for mass immunization in a few months can be considered one of the major breakthroughs in pharmacology over the past year. Despite of all seemingly indisputable advantages, none of RNA vaccines had reached Phase III of clinical trials since the moment of its discovery in 1993 until last year. The first experience of the successful use of mRNA vaccines was back in the 90s of the last century, when vaccination of mice with liposomes encoding an antigen-encoding mRNA was found to initiate specific immune response in mice. However, in these years, the method did not find application, due to the toxicity of lipids used. Subsequently, a large number of attempts have been made to develop vaccines against other viral infections, including Zika virus, Dengue virus, Ebola virus, cytomegalovirus, influenza virus and others. Despite the importance for preventing the spread of these diseases, the development of a vaccine preparation is a rather lengthy process, and final success is not guaranteed. However, the COVID-19 pandemic has become speeded the development of mRNA vaccines up.At the time of writing the review, two mRNA-based vaccines have been registered only in the world, both, BNT162b2 and mRNA-1273, were against COVID-19. Their effectiveness and safety are still actively studied. Moreover, it took less than a year for new strains of SARS-CoV-2 to appear, and the efficiency of vaccines against them was found to be lower than against the reference pathogen variant. Considering that the three new strains of SARS-CoV-2, “British”, “African” and “Brazilian”, are rapidly spreading in the world, the first results of efficiency evaluation of vaccines against them have already been published. One may expect that, considering mutations in these strains, the BNT162b2 and mRNA-1273 vaccines will remain effective against the “British” strain, but their protective properties are greatly weakened against the “African” variant.

Vaccine-Associated Disease Enhancement (VADE): Considerations in Postvaccination COVID-19

Introduction. The COVID-19 pandemic has entered a new phase with the roll-out of several vaccines worldwide at an accelerated phase. The occurrence of a more severe presentation of COVID-19 after vaccination may affect policymakers’ decision-making and vaccine uptake by the public. Vaccine-associated disease enhancement (VADE) is the modified presentation of infections in individuals after having received a prior vaccination. Currently, little is known about the potential of vaccine-associated disease enhancement (VADE) following COVID-19 immunization. Case Illustration. We herewith report two patients admitted with confirmed COVID-19 pneumonia with a history of CoronaVac vaccination. The first patient with a relatively milder course of the disease had received two doses of CoronaVac, whereas the second patient with a more progressive course of the disease received only one dose before developing symptoms and being admitted to the hospital. Our observations suggest that vaccination could act in boosting the inflammatory process and reveal the previously asymptomatic COVID-19 illness. Theoretically, vaccines could induce VADE, where only suboptimal, nonprotective titers of neutralizing antibodies were produced or proinflammatory T-helper type 2 response was induced. Secondly, enhanced respiratory disease (ERD) could manifest, where pulmonary symptoms are more severe due to peribronchial monocytic and eosinophilic infiltration. Understanding VADE is important for the decision-making by the public, clinicians, and policymakers and is warranted for successful vaccination uptake. Conclusion. We report two cases of patients developing COVID-19 shortly after CoronaVac vaccination in which VADE is likely. We recommend that current vaccination strategies consider the measurement of neutralizing antibody titer as a guide in ensuring the safest strategy for mass immunization. Studies are needed to investigate the true incidence of VADE on vaccinated individuals as well as on how to differentiate between VADE and severe manifestations of COVID-19 that are unrelated to vaccination.

Protection of Teleost Fish against Infectious Diseases through Oral Administration of Vaccines: Update 2021

Immersion and intraperitoneal injection are the two most common methods used for the vaccination of fish. Because both methods require that fish are handled and thereby stressed, oral administration of vaccines as feed supplements is desirable. In addition, in terms of revaccination (boosting) of adult fish held in net pens, oral administration of vaccines is probably the only feasible method to obtain proper protection against diseases over long periods of time. Oral vaccination is considered a suitable method for mass immunization of large and stress-sensitive fish populations. Moreover, oral vaccines may preferably induce mucosal immunity, which is especially important to fish. Experimental oral vaccine formulations include both non-encapsulated and encapsulated antigens, viruses and bacteria. To develop an effective oral vaccine, the desired antigens must be protected against the harsh environments in the stomach and gut so they can remain intact when they reach the lower gut/intestine where they normally are absorbed and transported to immune cells. The most commonly used encapsulation method is the use of alginate microspheres that can effectively deliver vaccines to the intestine without degradation. Other encapsulation methods include chitosan encapsulation, poly D,L-lactide-co-glycolic acid and liposome encapsulation. Only a few commercial oral vaccines are available on the market, including those against infectious pancreatic necrosis virus (IPNV), Spring viremia carp virus (SVCV), infectious salmon anaemia virus (ISAV) and Piscirickettsia salmonis. This review highlights recent developments of oral vaccination in teleost fish.

Urgent call for mass immunization against coronavirus in Bangladesh

Bangladesh showed initial success in the mass inoculation drive. However, the program was going through an alarming situation when the serum institute of India halted the shipments. Now the authority is administering US Moderna vaccines, Chinese Sinopharm vaccines, and Pfizer vaccines. Mass immunization is the only way for Bangladesh besides the present COVID-19 responses. Therefore, Bangladesh can utilize its previous experience in the roll-out of mass vaccination. The country can search for all available alternatives of COVID-19 vaccines besides maintaining diplomatic consistency with the existing sources for early vaccination of its population. The authority can try to get the committed vaccines from the COVAX program. Also, the country needs to maintain diplomatic relations with other global alliances that are promising support to poor and developing countries for the COVID-19 vaccine. The government can also consider direct purchases from vaccine manufacturers.

BNT162b2-Elicited Neutralization of Delta Plus, Lambda, and Other Variants

BNT162b2-elicited human sera are known to neutralize the currently dominant Delta SARS-CoV-2 variant. Here, we report the ability of 20 human sera, drawn 2 or 4 weeks after two doses of BNT162b2, to neutralize USA-WA1/2020 SARS-CoV-2 bearing variant spikes from Delta plus (Delta-AY.1, Delta-AY.2), Delta-∆144 (Delta with the Y144 deletion of the Alpha variant), Lambda, and B.1.1.519 lineage viruses. Geometric mean plaque reduction neutralization titers against Delta-AY.1, Delta-AY.2, and Delta-∆144 viruses are slightly lower than against USA-WA1/2020, but all sera neutralize the variant viruses to titers of ≥80. Neutralization titers against Lambda and B.1.1.519 variants and against USA-WA1/2020 are equivalent. The susceptibility of Delta plus, Lambda, and other variants to neutralization by the sera indicates that antigenic change has not led to virus escape from vaccine-elicited neutralizing antibodies and supports ongoing mass immunization with BNT162b2 to control the variants and to minimize the emergence of new variants.