What We Do Know and Do Not Yet Know about COVID-19 Vaccines as of the Beginning of the Year 2021

Anti-spike Antibody Status in Pre-vaccinated Healthy Participants and Rheumatoid Arthritis Patients During the Third Wave of COVID-19

Introduction Anti-spike severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies produced after infection with the coronavirus disease of 2019 (COVID-19) will offer protection and prevent re-infection for a few months. Seroprevalence studies measuring the SARS‑CoV-2 immunoglobulin G (IgG) levels will be helpful to know the herd immunity level that prevents community transmission. Very few studies have addressed the antibody titer among healthy participants and rheumatoid arthritis (RA) patients. The present study was conducted to determine the anti-spike SARS-CoV-2 antibody (Ab) status before COVID-19 vaccination in healthy participants and RA patients. Methodology A cross-sectional study was conducted at a tertiary care hospital to estimate the serum anti-spike antibody levels against COVID-19 among the pre-vaccinated healthy participants and patients with RA during the third wave of COVID-19. After receiving written informed consent, participants were recruited as per the inclusion and exclusion criteria. Demographic details, co-morbid status, and medication details were collected. Five milliliters of blood samples were collected, and anti-spike antibodies were estimated. The SARS-CoV-2 Ab positivity rate was expressed in percentage and was correlated with gender and age groups. Ab-positive participants were classified into three categories based on the neutralizing antibody titers (NAT). Results A total of 58 participants (49 healthy volunteers and nine RA patients) were recruited. Out of 58 participants, 40 were males, nine were females among healthy participants, and one male and eight females in the RA group were enrolled. Among the RA patients, one participant was found to have the chronic obstructive pulmonary disease (COPD), and two participants with hypothyroidism. Antibody positivity was found to be 83.6% among the healthy volunteers and 100% in the RA patients. About 48% had NAT between 50 and 90%. There was no significant difference for age and gender-specific positivity for SARS-CoV-2 neutralizing antibodies and neutralizing antibody titers among healthy participants. Conclusion Our study showed 84% positivity for anti-spike SARS-CoV-2 antibodies around the third wave (between November 2021 and February 2022). The majority had high neutralizing antibody titers. The probable reason for the SARS-CoV-2 antibody positivity before vaccination was either asymptomatic infection or herd immunity.

Anti-SARS-CoV-2 IgG Antibodies Post-COVID-19 or Post-Vaccination in Libyan Population: Comparison of Four Vaccines

Measurement of strength and durability of SARS-COV-2 antibody response is important to understand the waning dynamics of immune response to both vaccines and infection. The study aimed to evaluate the level of IgG antibodies against SARS-CoV-2 and their persistence in recovered, naïve, and vaccinated individuals. We investigated anti-spike RBD IgG antibody responses in 10,000 individuals, both following infection with SARS-CoV-2 and immunization with SARS-COV-2 AstraZeneca, Sputnik V, Sinopharm, and Sinovac. The mean levels of anti-spike IgG antibodies were higher in vaccinated participants with prior COVID-19 than in individuals without prior COVID-19. Overall, antibody titers in recovered vaccinee and naïve vaccinee persisted beyond 20 weeks. Vaccination with adenoviral-vector vaccines (AstraZeneca and Sputnik V) generates higher antibody titers than with killed virus vaccine (Sinopharm and Sinovac). Approximately two-thirds of asymptomatic unvaccinated individuals had developed virus-specific antibodies. A single dose of vaccine is likely to provide greater protection against SARS-CoV-2 infection in individuals with apparent prior SARS-CoV-2 infection, than in SARS-CoV-2-naive individuals. In addition, the high number of seropositivity among asymptomatic unvaccinated individuals showed that the number of infections are probably highly underestimated. Those vaccinated with inactivated vaccine may require more frequent boosters than those vaccinated with adenoviral vaccine. These findings are important for formulating public health vaccination strategies during COVID-19 pandemic.

Durability of SARS-CoV-2 Specific IgG Antibody Responses Following Two Doses of Match and Mixed COVID-19 Vaccines Regimens in Saudi Population

Background

SARS-CoV-2 pandemic continues to threaten the human population with millions of infections and deaths worldwide. Vaccination campaigns undertaken by several countries have resulted in a notable decrease in hospitalization and deaths. However, with the emergence of new virus variants, it is critical to determine the longevity and the protection efficiency provided by the current authorized vaccines.

Aim

The aims of this study are to provide data about the magnitude of immune responses in individuals fully vaccinated against COVID-19 in Riyadh province of Saudi Arabia. Also, to evaluate the continuity of specific IgG levels and compare the titers in individuals who have been received two doses of the matched and mixed vaccines, including Pfizer and AstraZeneca against SARS-CoV-2 during the period of three to six months. Moreover, we analyze the current state of immune response in terms of antibody responses in thepopulation postvaccination using homogenous or hetrogenous vaccine regimen.

Methods

A total of 141 healthy volunteers were recruited to our study; blood (n=63) and the saliva samples (n=78) and were collected from fully vaccinated individuals in Riyadh city. We employed a specific ELISA assay in plasma and saliva of fully vaccinated individuals.

Results

IgG levels varied with age groups with the highest concentration in the age group 19–29 years, but the age group (≥50) had the lowest IgG concentration. The IgG levels in both serum and saliva were higher after three months and start to wane after six months. Individuals who received mixed types of vaccines had significantly better response than Pfizer vaccine alone.

Conclusion

The current study investigates the status of humoral responses in different age groups, in terms of antibody measurements. These data will help to evaluate the need for further COVID-19 vaccine doses and to what extent a two-dose regimen will protect vaccinated individuals.

Antibodies to the Spike Protein Receptor-Binding Domain of SARS-CoV-2 at 4–13 Months after COVID-19

Identification of factors behind the level and duration of persistence of the SARS-CoV-2 antibodies in the blood is assumed to set the direction for studying humoral immunity mechanisms against COVID-19, optimizing the strategy for vaccine use, antibody-based drugs, and epidemiological control of COVID-19. Objective: This study aimed to study the relationship between clinical and demographic characteristics and the level of IgG antibodies to the RBD of SARS-CoV-2 spike protein after COVID-19 in the long term. Residents of the Altai Region of Western Siberia of Russia, Caucasians, aged from 27 to 93 years (median 53.0 years), who recovered from COVID-19 between May 2020 and February 2021 (n = 44) took part in this prospective observational study. The titer of IgG antibodies to the RBD of SARS-CoV-2 spike protein was measured repeatedly in the blood at 4–13 months from the beginning of the clinical manifestation of COVID-19 via the method of enzyme-linked immunosorbent assay. The antibody titer positively correlated with age (p = 0.013) and COVID-19 pneumonia (p = 0.002) at 20–40 and 20–24 weeks from the onset of COVID-19 symptoms, respectively. Age was positively associated with antibody titer regardless of history of COVID-19 pneumonia (beta regression coefficient p = 0.009). The antibody titer decreased in 15 (34.1%) patients, increased in 10 (22.7%) patients, and did not change in 19 (43.2%) patients from the baseline to 48–49 weeks from the onset of COVID-19 symptoms, with seropositivity persisting in all patients. Age and COVID-19 pneumonia are possibly associated with higher IgG antibodies to the spike protein RBD of SARS-CoV-2 following COVID-19 in the long term. Divergent trends of anti-RBD IgG levels in adults illustrate inter-individual differences at 4–13 months from the onset of COVID-19 symptoms.

A comprehensive account of SARS-CoV-2 genome structure, incurred mutations, lineages and COVID-19 vaccination program

This review collates information on the onset of COVID-19, SARS-CoV-2 genome architecture, emergence of novel viral lineages that drove multiple waves of infection around the world and standard and fast track development of vaccines. With the passage of time, the continuously evolving SARS-CoV-2 has acquired an expanded mutational landscape. The functional characterization of spike protein mutations, the primary target of diagnostics, therapeutics and vaccines has revealed increased transmission, pathogenesis and immune escape potential in the variant lineages of the virus. The incurred mutations have also resulted in substantial viral neutralization escape to vaccines, monoclonal, polyclonal and convalescent antibodies presently in use. The present situation suggests the need for development of precise next-generation vaccines and therapeutics by targeting the more conservative genomic viral regions for providing adequate protection.

An Update on the Status of Vaccine Development for SARS-CoV-2 Including Variants. Practical Considerations for COVID-19 Special Populations

The progress in the development of various vaccine platforms against SARS-CoV-2 have been rather remarkable owing to advancement in molecular and biologic sciences. Most of the current vaccines and those in development focus on targeting the viral spike proteins by generating antibodies of varying spectrum. These vaccines represent a variety of platforms including whole virus vaccines, viral vector vaccines, nucleic acid vaccines representing RNA, DNA, and their hybrid forms.The therapeutic efficacy of these vaccines varies owing to their pharmacodynamic individualities. COVID-19 variants are capable of inducing different pathologic responses and some of which may be resistant to antibodies generated by current vaccines. The current clinical use of these vaccines has been through emergency use authorization until recently. Moreover, the efficacy and safety of these vaccines have been tested in substantial numbers of individuals but studies in special populations that better reflect the global population are pending results. These specialized populations include young children, immunocompromised patients, pregnant individuals, and other specialized groups. Combination approaches, molecularly modified vaccination approaches, and vaccines conferring longer periods of immunity are being currently being investigated, as well as pharmacovigilance studies.The continual transformation of SARS-CoV-2 and its variants are of concern along with the breakthrough infections. These considerations pose new challenges for the development of vaccination platforms. For this purpose, booster doses, combination vaccine approaches, and other modalities are being discussed. This review provides an updated account of currently available vaccines and those in advanced development with reference to their composition and mechanisms of action.A discussion on the use of vaccines in special populations including immunocompromised patients, pregnant women and other specialized populations are also included.

Points to consider for COVID-19 vaccine quality control and national lot release in Republic of Korea: focus on a viral vector platform

Due to the global public health crisis caused by the coronavirus disease 2019 (COVID-19) pandemic, the importance of vaccine development has increased. In particular, a rapid supply of vaccines and prompt deployment of vaccination programs are essential to prevent and overcome the spread of COVID-19. As a part of the vaccine regulations, national lot release is regulated by the responsible authorities, and this process involves the assessment of the lot before a vaccine is marketed. A lot can be released for use when both summary protocol (SP) review and quality control testing are complete. Accelerated lot release is required to distribute COVID-19 vaccines in a timely manner. In order to expedite the process by simultaneously undertaking the verification of quality assessment and application for approval, it is necessary to prepare the test methods before marketing authorization. With the prolonged pandemic and controversies regarding the effectiveness of the COVID-19 vaccine against new variants, public interest for the development of a new vaccine are increasing. Domestic developers have raised the need to establish standard guidance on the requirements for developing COVID-19 vaccine. This paper presents considerations for quality control in the manufacturing process, test items, and SP content of viral vector vaccines.

Analyses of Confirmed COVID-19 Cases Among Korean Military Personnel After Mass Vaccination

BACKGROUND

The military was one of the first groups in Korea to complete mass vaccination against the coronavirus disease 2019 (COVID-19) due to their high vulnerability to COVID-19. To confirm the effect of mass vaccination, this study analyzed the patterns of confirmed cases within Korean military units.

METHODS

From August 1 to September 15, 2021, all epidemiological data regarding confirmed COVID-19 cases in military units were reviewed. The number of confirmed cases in the units that were believed to have achieved herd immunity (i.e., ≥ 70% vaccination) was compared with the number of cases in the units that were not believed to have reached herd immunity (< 70% vaccination). Additionally, trends in the incidence rates of COVID-19 in the military and the entire Korean population were compared.

RESULTS

By August 2021, 85.60% of military personnel were fully vaccinated. During the study period, a total of 174 COVID-19 cases were confirmed in the 39 units. More local transmission (herd immunity group vs. non-herd immunity group [%], 1 [0.91] vs. 39 [60.94]) and hospitalizations (12 [11.01] vs. 13 [27.08]) occurred in the units that were not believed to have achieved herd immunity. The percentage of fully vaccinated individuals among the confirmed COVID-19 cases increased over time, possibly due to the prevalence of the delta variant. Nevertheless, the incidence rate remained lower in military units than in the general Korean population.

CONCLUSION

After completing mass vaccination, the incidence rates of COVID-19 infection in the military were lower than those in the national population. New cluster infections did not occur in vaccinated units, thereby suggesting that herd immunity has been achieved in these military units. Further research is needed to determine the extent to which levels of non-pharmacological intervention can be reduced in the future.

Steroid injections in pain management: influence on coronavirus disease 2019 vaccines

The coronavirus disease 2019 (COVID-19) pandemic, which has been rampant since the end of 2019, has evidently affected pain management in clinical practice. Fortunately, a COVID-19 vaccination program is currently in progress worldwide. There is an ongoing discussion that pain management using steroid injections can decrease COVID-19 vaccine efficacy, although currently there is no direct evidence to support this statement. As such, the feeling of pain in patients is doubled in addition to the co-existing ill-effects of social isolation associated with the pandemic. Thus, in the COVID-19 era, it has become necessary that physicians be able to provide high quality pain management without negatively impacting COVID-19 vaccine efficacy. Steroids can alter the entire process involved in the generation of adaptive immunity after vaccination. The period of hypophysis-pituitary-adrenal axis suppression is known to be 1 to 4 weeks after steroid injection, and although the exact timing for peak efficacy of COVID-19 vaccines is slightly different for each vaccine, the average is approximately 2 weeks. It is suggested to avoid steroid injections for a total of 4 weeks (1 week before and after the two vaccine doses) for the double-shot vaccines, and for 2 weeks in total (1 week before and after vaccination) for a single-shot vaccine. This review focuses on the basic concepts of the various COVID-19 vaccines, the effect of steroid injections on vaccine efficacy, and suggestions regarding an appropriate interval between the administration of steroid injections and the COVID-19 vaccine.

Advances in the design and development of SARS-CoV-2 vaccines

Since the end of 2019, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. The RNA genome of SARS-CoV-2, which is highly infectious and prone to rapid mutation, encodes both structural and nonstructural proteins. Vaccination is currently the only effective method to prevent COVID-19, and structural proteins are critical targets for vaccine development. Currently, many vaccines are in clinical trials or are already on the market. This review highlights ongoing advances in the design of prophylactic or therapeutic vaccines against COVID-19, including viral vector vaccines, DNA vaccines, RNA vaccines, live-attenuated vaccines, inactivated virus vaccines, recombinant protein vaccines and bionic nanoparticle vaccines. In addition to traditional inactivated virus vaccines, some novel vaccines based on viral vectors, nanoscience and synthetic biology also play important roles in combating COVID-19. However, many challenges persist in ongoing clinical trials.

DNA vaccines for SARS-CoV-2: toward third-generation vaccination era

Introduction: Coronavirus outbreak 2019 (COVID-19) has affected all the corners of the globe and created chaos to human life. In order to put some control on the pandemic, vaccines are urgently required that are safe, cost effective, easy to produce, and most importantly induce appropriate immune responses and protection against viral infection. DNA vaccines possess all these features and are promising candidates for providing protection against SARS-CoV-2.Area covered: Current understanding and advances in DNA vaccines toward COVID-19, especially those under various stages of clinical trials.Expert opinion: Through DNA vaccines, host cells are momentarily transformed into factories that produce proteins of the SARS-CoV-2. The host immune system detects these proteins to develop antibodies that neutralize and prevent the infection. This vaccine platform has additional benefits compared to traditional vaccination strategies like strong cellular immune response, higher safety margin, a simple production process as per cGMP norms, lack of any infectious agent, and a robust platform for large-scale production.

Analysis of a COVID-19 Prescreening Process in an Outpatient Clinic at a University Hospital during the COVID-19 Pandemic

BACKGROUND

To minimize nosocomial infection against coronavirus disease 2019 (COVID-19), most hospitals conduct a prescreening process to evaluate the patient or guardian of any symptoms suggestive of COVID-19 or exposure to a COVID-19 patient at entrances of hospital buildings. In our hospital, we have implemented a two-level prescreening process in the outpatient clinic: an initial prescreening process at the entrance of the outpatient clinic (PPEO) and a second prescreening process is repeated in each department. If any symptoms or epidemiological history are identified at the second level, an emergency code is announced through the hospital's address system. The patient is then guided outside through a designated aisle. In this study, we analyze the cases missed in the PPEO that caused the emergency code to be applied.

METHODS

All cases reported from March 2020 to April 2021 were analyzed retrospectively. We calculated the incidence of cases missed by the PPEO per 1,000 outpatients and compared the incidence between first-time hospital visitors and those visiting for the second time or more; morning and afternoon office hours; and days of the week.

RESULTS

During the study period, the emergency code was applied to 449 cases missed by the PPEO. Among those cases, 20.7% were reported in otorhinolaryngology, followed by 11.6% in gastroenterology, 5.8% in urology, and 5.8% in dermatology. Fever was the most common symptom (59.9%), followed by cough (19.8%). The incidence of cases per 1,000 outpatients was significantly higher among first-time visitors than among those visiting for the second time or more (1.77 [confidence interval (CI), 1.44-2.10] vs. 0.59 [CI, 0.52-0.65], respectively) (P < 0.001).

CONCLUSION

Fever was the most common symptom missed by the PPEO, and otorhinolaryngology and gastroenterology most frequently reported missed cases. Cases missed by the PPEO were more likely to occur among first-time visitors than returning visitors. The results obtained from this study can provide insights or recommendations to other healthcare facilities in operating prescreening processes during the COVID-19 pandemic.

Reported COVID-19 vaccines side effects among Jordanian population: a cross sectional study

Concerns about the safety and side effects of coronavirus SARS CoV2 vaccines have been raised among many communities worldwide. The aim of this study was to describe the side effects reported by vaccinated individuals in Jordan. A cross-sectional survey was used to recruit responses from participants who were vaccinated with either one dose or both doses of any of the administered vaccines in Jordan (AstraZeneca, Pfizer, Sinopharm). A total of 1,086 participants were enrolled in the study. Most of participants have not been infected with SARS CoV2 before receiving the vaccine (77.2%). Larger proportion of the study population received Pfizer vaccine (40.6%) followed by the AstraZeneca vaccine (33.0%), and Sinopharm vaccine (26.4%). Side effects after receiving the first dose of the vaccine were reported by most participants (89.9%) and included pain at the injection site (78.4%), fatigue (51.8%), myalgia (37.6%), headache (33.1%), and chills (32.3%). To a lesser extent, there were gastrointestinal side effects such as nausea (15.1%), loss of appetite (9.4%), and diarrhea (6.4%). More side effects were significantly associated with AstraZeneca vaccine (P < .001). Only one case for each of second dose of Pfizer and Sinopharm vaccines reported that their side effects required hospitalization. In this study, we found that people in Jordan experienced more side effects with AstraZeneca vaccine followed by Pfizer vaccine and the least one is Sinopharm vaccine. Our study showed that these side effects are not severe and should not be an obstacle against the successful control of the pandemic in Jordan.

Antibody Responses to Natural SARS-CoV-2 Infection or after COVID-19 Vaccination

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is the causative agent of the ongoing pandemic of coronavirus disease 2019 (COVID-19). The clinical severity of COVID-19 ranges from asymptomatic to critical disease and, eventually, death in smaller subsets of patients. The first case of COVID-19 was declared at the end of 2019 and it has since spread worldwide and remained a challenge in 2021, with the emergence of variants of concern. In fact, new concerns were the still unclear situation of SARS-CoV-2 immunity during the ongoing pandemic and progress with vaccination. If maintained at sufficiently high levels, the immune response could effectively block reinfection, which might confer long-lived protection. Understanding the protective capacity and the duration of humoral immunity during SARS-CoV-2 infection or after vaccination is critical for managing the pandemic and would also provide more evidence about the efficacy of SARS-CoV-2 vaccines. However, the exact features of antibody responses that govern SARS-CoV-2 infection or after vaccination remain unclear. This review summarizes the main knowledge that we have about the humoral immune response during COVID-19 disease or after vaccination. Such knowledge should help to optimize vaccination strategies and public health decisions.

Intracerebral Hemorrhage due to Thrombosis with Thrombocytopenia Syndrome after Vaccination against COVID-19: the First Fatal Case in Korea

Vaccination with an adenoviral vector vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can result in the rare development of thrombosis with thrombocytopenia mediated by platelet-activating antibodies against platelet factor 4 (PF4). This is a life-threating condition that may be accompanied by bleeding due to thrombocytopenia with thrombosis of the cerebral venous sinus or splanchnic vein. Herein, we describe the first fatal case of thrombosis with thrombocytopenia syndrome in Korea, presenting with intracranial hemorrhage caused by cerebral venous sinus thrombosis. A 33-year-old Korean man received the first dose of the ChAdOx1 nCoV-19 vaccination. He developed severe headache with vomiting 9 days after the vaccination. Twelve days after vaccination, he was admitted to the hospital with neurological symptoms and was diagnosed with cerebral venous sinus thrombosis, which was accompanied by intracranial hemorrhage. Thrombocytopenia and D-dimer elevation were observed, and the result of the PF4 enzyme-linked immunosorbent assay antibody test was reported to be strongly positive. Despite intensive treatment, including intravenous immunoglobulin injection and endovascular mechanical thrombectomy, the patient died 19 days after vaccination. Physicians need to be aware of thrombosis with thrombocytopenia syndrome (TTS) in adenoviral vector-vaccinated patients. Endovascular mechanical thrombectomy might be a useful therapeutic option for the treatment of TTS with cerebral venous sinus thrombosis.

A Summary of the SARS-CoV-2 Vaccines and Technologies Available or under Development

Since the beginning of 2020, the world has been in a race to develop vaccines that can control the COVID-19 pandemic. More than 250 projects have been initiated for this purpose, but only 14 of them have been authorized for use, despite being in phase 3 clinical trials. More than 40 other vaccines are also in phase 1/2 clinical trials and show promising outcomes. Regarding the appropriate choice of vaccines for each country or region, we reviewed the currently used vaccines in light of the different influencing parameters. These factors include the mode of action, dosage protocol, age group of the vaccinee, side effects, storage conditions, mounted immune response, and cost. Technically, there are seven types of vaccines developed against SARS-CoV-2: messenger RNA (mRNA), nonreplicating and replicating vectors, inactivated viruses, protein subunits, viral-like particles, DNA vaccines, and live attenuated vaccines. The mRNA type is being used for the first time in humans. Unfortunately, mutated variants of SARS-CoV-2 have started to appear worldwide, and researchers are investigating the effects of the currently used vaccines on them. There are many concerns regarding the long-term protection afforded by these vaccines and their side effects, and whether they require future modifications to be effective against the mutated variants. The development of new vaccines using more advanced technology is paramount for overcoming the difficulties in controlling the COVID-19 pandemic across the world.

A comprehensive overview of vaccines developed for pandemic viral pathogens over the past two decades including those in clinical trials for the current novel SARS-CoV-2

The unprecedented coronavirus disease 2019 (COVID-19) is triggered by a novel strain of coronavirus namely, Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). Researchers are working around the clock to control this pandemic and consequent waves of viral reproduction, through repurposing existing drugs as well as designing new vaccines. Several countries have hastened vaccine design and clinical trials to quickly address this outbreak. Currently, more than 250 aspirants against SARS-CoV-2 are in progress, including mRNA-replicating or non-replicating viral vectored-, DNA-, autologous dendritic cell-based-, and inactivated virus-vaccines. Vaccines work by prompting effector mechanisms such as cells/molecules, which target quickly replicating pathogens and neutralize their toxic constituents. Vaccine-stimulated immune effectors include adjuvant, affinity, avidity, affinity maturation, antibodies, antigen-presenting cells, B lymphocytes, carrier protein, CD4+ T-helper cells. In this review, we describe updated information on the various vaccines available over the last two decades, along with recent progress in the ongoing battle developing 63 diverse vaccines against SARS-CoV-2. The inspiration of our effort is to convey the current investigation focus on registered clinical trials (as of January 08, 2021) that satisfy the safety and efficacy criteria of international wide vaccine development.

China is facing serious experimental monkey shortage during the COVID-19 lockdown

This report aims to analyze the experimental monkey shortage generated by the COVID‐19 lockdown. The supply capability of the monkey breeding farms is insufficient to meet demand, and the sales prices have skyrocketed since 2018. The contradiction will be further aggravated with import prohibition although the countermeasures suggested.

COVID-19: Insights into Potential Vaccines

People around the world ushered in the new year 2021 with a fear of COVID-19, as family members have lost their loved ones to the disease. Millions of people have been infected, and the livelihood of many has been jeopardized due to the pandemic. Pharmaceutical companies are racing against time to develop an effective vaccine to protect against COVID-19. Researchers have developed various types of candidate vaccines with the release of the genetic sequence of the SARS-CoV-2 virus in January. These include inactivated viral vaccines, protein subunit vaccines, mRNA vaccines, and recombinant viral vector vaccines. To date, several vaccines have been authorized for emergency use and they have been administered in countries across the globe. Meanwhile, there are also vaccine candidates in Phase III clinical trials awaiting results and approval from authorities. These candidates have shown positive results in the previous stages of the trials, whereby they could induce an immune response with minimal side effects in the participants. This review aims to discuss the different vaccine platforms and the clinical trials of the candidate vaccines.