covid-19 vaccines

The nemesis: SARS-CoV-2 pandemic: Leaving in its wake millions of infections, accompanied by an immense magnitude of morbidity and multitude of mortality, and an unfathomable economic toll, the COVID-19 pandemic has led to a global calamity. An effective and safe COVID-19 vaccine is urgently needed to prevent the disease, thwart the complications and avert deaths resulting from unrestrained transmission of the infection. The hubris: Vaccine development: While most of the platforms of vaccine candidates have focused on the spike (S) protein and its variants as the primary antigen of COVID-19 infection, various techniques involved include nucleic acid technologies (RNA and DNA), non-replicating viral vectors, peptides, recombinant proteins, live attenuated and inactivated viruses. There are novel vaccine technologies being developed using next-generation strategies for precision and flexibility for antigen manipulation relating to SARS-CoV-2 infection mechanisms. The elpis: Updates and prospects: There were nine different technology platforms under research and development to create an effective vaccine against COVID 19. Although there are no licensed vaccines against COVID-19 yet, there are various potential vaccine candidates under development and advanced clinical trials. Out of them, one having undergone phase III clinical trials, has become available in some countries for use among the high-risk groups following emergency use authorization. Other COVID-19 vaccines may soon follow the suit. Conclusion: Hopes and concerns: The hope of benefiting from the vaccine to the extent that it may be the only way to tide over and control the COVID-19 pandemic, is accompanied by the likely fear of adverse effects and opposition in public for COVID-19 vaccination, including the vaccine hesitancy. Further, there is concern among scientific circles that vaccine may have opposite of the desired effect by causing antibody-dependent disease enhancement.

Introduction: SARS-CoV-2 life cycle: The disease which reportedly began in Chinese city Wuhan in November-December 2019 manifesting as severe respiratory illness, soon spread to various parts of the world, and was named COVID-19, and declared a pandemic by WHO. The life cycle of SARS-CoV-2 begins with membrane fusion mediated by Spike (S) protein binding to the ACE2 receptors. Following viral entry and release of genome into the host cell cytoplasm there occurs replication and transcription to generate viral structural and non-structural proteins. Finally, VLPs are produced and the mature virions are released from the host cell. Immunogenicity of the spike protein: The S protein is considered the main antigenic component among structural proteins of SARS-CoV-2 and responsible for inducing the host immune response. The neutralising antibodies (nAbs) targeting the S protein are produced and may confer a protective immunity against the viral infection. Further, the role of the S protein in infectivity also makes it an important tool for diagnostic antigen-based testing and vaccine development. The S-specific antibodies, memory B and circulating TFH cells are consistently elicited following SARS-CoV-2 infection, and COVID-19 vaccine shots in clinical trials. The emerging SARS-CoV-2 variants: The early genomic variations in SARS-CoV-2 have gone almost unnoticed having lacked an impact on disease transmission or its clinical course. Some of the recently discovered mutations, however, have impact on transmissibility, infectivity, or immune response. One such mutation is the D614G variant, which has increased in prevalence to currently become the dominant variant world-over. Another, relatively new variant, named VUI-202012/01 or B.1.1.7 has acquired 17 genomic alterations and carries the risk of enhanced infectivity. Further, its potential impact on vaccine efficacy is a worrisome issue. Conclusion: THE UNMET CHALLENGES: COVID-19 as a disease and SARS-CoV-2 as its causative organism, continue to remain an enigma. While we continue to explore the agent factors, disease transmission dynamics, pathogenesis and clinical spectrum of the disease, and therapeutic modalities, the grievous nature of the disease has led to emergency authorizations for COVID-19 vaccines in various countries. Further, the virus may continue to persist and afflict for years to come, as future course of the disease is linked to certain unknown factors like effects of seasonality on virus transmission and unpredictable nature of immune response to the disease.

Monkeypox is a rare zoonotic infection originating in the regions of Central and West Africa. The global threat has been arising since monkeypox is spreading outside of the endemic regions. Pakistan has recently exhausted health funds in a quarrel against SARS-CoV-2, by supplying expensive COVID-19 vaccines to the general public, free of cost. Pakistan’s government has remarkably contributed to lowering the suffering of COVID-19-affected patients by granting the Sehat Sahulat Programme and similar health initiatives to restrict viral propagation in the general public. However, despite all efforts the major constraints are a lack of international funds and limitations on the budget of healthcare systems and medical facilities. Newly emerged cases of monkeypox are very threatening to Pakistan’s economy and health. Therefore, it is very necessary that healthcare authorities take effective measures like surveillance, early identification, separation, monitoring of contacts, immunization, and public awareness in order to stop the spread of the virus and control monkeypox outbreaks.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) outbursts began at the end of 2019, which imposed a serious crisis on public health and the economy all over the world. To date, there is no antiviral drug available for SARS-CoV-2, and hence vaccination is the most preferred method to prevent people from getting attacked by this virus, especially for those who are at high risk. To counter coronavirus-2, there are various types of vaccines, which are being used, such as live attenuated vaccines, killed or inactivated vaccines, recombinant vaccines, mRNA vaccines, recombinant vector vaccines, and DNA vaccines. Novavax data shows that the vaccine is effective against severe diseases caused by B.1.351. The Pfizer-BioNTech and AstraZeneca vaccines show evidence of some protection against P.1. Due to the immune response, the Human body can recognize and protect itself against harmful foreign substances such as bacteria, viruses, and microorganisms. The immune system protects our body from these harmful substances by identifying them as antigens. Virus-infected cells release many chemicals such as chemokines and cytokines for the initiation of immune response. To control the pandemic situation, herd immunity is required by the immunization of a critical mass of the world population at once. In this review article, we have made an analysis of the immune response of the human body to SARS-CoV-2 infection, different types, and modes of action of SARS-CoV-2 vaccines along with the current status of vaccines.