Vaccines and challenges

More than 74 million cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of 2019 coronavirus disease (Covid-19), have been reported worldwide since December 2019. , More than 1.6 million people have died. To devastate public health, the world economy and social order.

Safe to prevent pandemics through SARS-CoV-2 infection, viral shedding, human transmission, disease severity, hospitalization and mortality, and to minimize post-infection complications and potential viruses There is an urgent need for an effective and effective vaccine. Infection from humans to specific animal species and vice versa.

Typical outcomes desired for a successful vaccination campaign include a statistically significant reduction in infection and the severity or duration of infection of the resulting clinical illness. The main goal of vaccine dissemination is to develop herd immunity, also known as mass defense. Generally, to show herd immunity to pathogens such as SARS-CoV-2, it is necessary to immunize about 65-70 percent of the population in the geographic area.

Vaccine development against SARS-CoV-2, like other important pathogens, is a costly, time-dependent, and painstaking process that can usually take 10 years or more. It consists of exploration, preclinical, clinical, review and approval stages, post-licensing manufacturing (first small, then large), and post-marketing research and quality control. Preclinical stages may include in vitro studies in cell culture and in vivo studies in animal models such as mice, Syrian hamsters, ferrets, and rhesus monkeys. The clinical stage consists of three stages. Phase I, a safety trial in a small number of individuals, Phase II, where safety trials are expanded from hundreds to thousands, and Phase III, a vaccine efficacy trial that I usually perform in thousands.

Currently, more than 200 Covid-19 vaccines using multiple platforms are being developed at various research facilities around the world. It is noteworthy that some vaccine candidates participated in or completed Phase III clinical trials within a year. Recent approvals and approvals of the Covid-19 vaccines from Pfizer and BioNTech, Moderna, and AstraZeneca-University of Oxford are based on the statistically significant efficacy of these vaccines in Phase III clinical trials. This is very encouraging, but it will take a considerable amount of work to overcome some of the challenges ahead.

The most important efficacy endpoint is protection against severe illness and mortality, which is difficult to assess in Phase III randomized clinical trials. Moreover, vaccine efficacy does not always predict vaccine efficacy. That is, protection from vaccines that are not given randomly. Under field conditions, age, ethnicity, gender, comorbidities, individual immunity, political issues, vaccine hesitation, infrastructure differences, quality assurance, management and maintenance, cold chain distribution and storage temperature, geological inheritance Gaku, cross-immunization from existing immunity to SARS-CoV-2 and other coronavirus infections, timely vaccine distribution and inoculation, compatibility of vaccines with field strains of SARS-CoV-2, affordability and literacy rate .. Covid-19 is more common and severe among individuals who are often underestimated in clinical trials, such as the elderly, people with chronic illness, racial and ethnic minority populations. Different groups of people may not have the same level of immune response to vaccination.

Therefore, many unanswered questions require post-vaccination evaluation. First, assess how effective a high-risk individual’s vaccine is. Second, how effectively the vaccine protects against severe Covid-19. Third, how the vaccine effectively prevents the transmission of the virus from infected to susceptible individuals. Fourth, the magnitude of protection for the entire population subgroup, as defined by age, race and ethnicity. Fifth, the duration of protection provided by the different vaccine types. Sixth, a more comprehensive understanding of the long-term safety of various Covid-19 vaccines, including rare complications. Vaccination may be associated with mild adverse events such as injection site pain, fever, malaise, and myalgia. More serious reactions, such as neurological or inflammatory processes that are not explained for other reasons, raise concerns. Seventh, the duration of spontaneous immunity to SARS-CoV-2 infection is not definitive and can decline over time. The eighth protective and pathogenic aspect of the immune response to SARS-VoV-2 is not fully understood as scientists understand the pathogenesis of this new virus, host immune response, and disease. Hmm. The correlation of defense against SARS-CoV-2 in Covid-19 has not yet been definitively established. It has not yet been determined whether it is a systemic antibody-mediated (IgG), T-cell-mediated, or local (IgA or mucosal) immune response. The upper respiratory tract or a combination of these reactions protects sensitive individuals. Antibody-dependent enhancement (ADE) of infections reported in other rare coronavirus infections may also be of concern. Just as the seasonal influenza vaccine is updated annually to match the vaccine virus strain with the field virus strain, the Covid-19 vaccine needs to be updated regularly to match the vaccine’s target antigen with the field strain. There is a possibility. Since SARS-CoV-2 is an RNA virus, it continues to evolve genetically and phenotypically. Last but not least, does the Covid-19 vaccine prevent the development of clinical disease and viral infections? Different transmission routes and the type of immunity that provides the best protection can also determine the type of vaccine development.

The Covid-19 vaccine alone cannot end the pandemic immediately. Due to the many variables involved, effective vaccines and hygiene measures are needed to control the current pandemic. If this is successful, it can take another year or two. Therefore, the public must continue to comply with public health measures such as social distance, hand washing, best personal and public hygiene practices, and wearing masks. The Covid-19 scenario emphasizes the One-Health concept, global interoperability, the importance of global health security, and the need for appropriate resources and investment in science and research. Interdisciplinary cooperation and efforts at the individual, regional, national and global levels are paramount to ending the pandemic and bringing it back to life as we know it.