Introduction
In January 2020, COVID-19 began to show signs of developing into a significant issue on a global scale. The spread of the pandemic was also slowed by the introduction of vaccines. The administration of these vaccines was by injection. While there are currently no vaccines for COVID-19 that can be administered by the oral route, clinical trials for oral vaccines are underway and are showing promising results. This article is all about knowing the advantages of oral vaccination and the clinical trials of oral vaccine pills.
Is Oral Immunization Effective?
Oral administration of the COVID-19 vaccine is markedly a potential immunologic strategy in the near future by the pharmaceutical giants who are looking at ways to battle the global pandemic effectively. Firstly, oral immunization has been a viable strategy to combat respiratory illnesses in numerous clinical trials. The examples being the enteric-coated adenovirus type 4 and type 7 vaccines administered in US military personnel between 17 to 50 years of age and the recently administered oral influenza vaccine that has successfully progressed to Phase 2 trials.
Secondly, oral vaccination is also meant to produce mucosal immunity (humoral and cell-mediated immunity) against future respiratory problems. The ease of oral inoculation removes the need for trained healthcare professionals to administer the vaccine and minimizes the risk of cross-infection in healthcare centers providing vaccination. In countries and specifically, areas with limited resource settings and where social distancing is harder to implement, we see surges in COVID cases. The practicality of oral vaccine distribution is more adaptable and beneficial.
The manufacturing process of these vaccines also highlights the easy access and scalability of the approach. The future strategy to combat the pandemic’s repeated waves would lie in the double advantage of accelerating herd immunity in the population and also the employability of these vaccines in resource-limited dense population settings. The results after Phase 1 clinical trials and some vaccines which have already entered phase 2 trials show broad effectiveness against the novel Coronavirus and would have the chances of being successfully implemented by the year-end of 2021 or the early half of 2022, according to researchers.
1) Oral Remdesivir:
Early clinical trials of Remdesivir in healthy volunteers have been wrapped up by Jubilant Pharma. The company is yet to get this oral formulation authorized in India and in several other countries. The absorption safety is considered similar to the injectable form of the drug. A 5-day course of the oral formulation of the drug is what is being reviewed by the researchers in animals and healthy human volunteers.
2) Pfizer Trials:
The US-based pharmaceutical company, Pfizer’s chief executive officer, said that the company’s COVID-19 oral antiviral pill in early-stage trials will be ready mostly by the end of this year and would launch in early 2022. In addition, Pfizer Inc. announced in March 2021 the initiation of phase 1 trials of an orally administered therapeutic drug against COVID-19 variants. The phase 1 trial is a randomized, double-blind, placebo-controlled, sponsor -open and multiple-dose escalation study in healthy adults evaluating the safety and pharmacokinetics, and tolerability of PF-07321332. The oral antiviral candidate PF -07321332 is potent in vitro protease inhibitor as per research and study suggesting potential use in the treatment of people infected by the novel coronavirus that is the SARS-CoV-2 pathogen, and also against the future variants of this virus.
Mechanism of Action - According to the trials underway, the protease inhibitor works by preventing the virus from replicating in the body cells. Previously protease inhibitors were also successfully administered against HIV and Hepatitis C virus in combination with other antivirals. The drug is a part of the class of medicines (protease inhibitors) that inhibit the enzyme the virus needs to replicate in the human cell.
3) Vaxart Vaccine Trials:
Vaxart company has released a statement in May 2021 that says that its VXA-Cov2-1 oral COVID-19 tablet would yield broad cross coronavirus activity as per its phase 1 trials. The vaccine includes spike and nucleocapsid SARS COV-2 proteins.
Mechanism of Action - The vaccines have shown substantial CD8+ T-cell responses that trigger specific antibodies or mucosal immunoglobulin A that appears to be cross-reactive against the novel Coronavirus. No serious adverse effects have been reported in the trials, and the data so far as per research has been promising compared to other oral vaccine formulations as per researchers.
4) Immunity Biotech UK Trials:
Immunity Bio is a leading late clinical-stage immunotherapy company developing next-generation therapeutics against infectious diseases.
Mechanism of Action - Immunity Bio has reported initial data from phase 1 clinical trial of its hAd5 COVID-19 vaccine candidate, which stimulated the generation of T-cells reacting to vaccine delivered spike (S) and nucleocapsid. It is reportedly protective against non-human primates from high titers SARS COV-2 challenge when administered as subcutaneous prime with oral boost administration. The efficacy of the oral capsule formulation of the vaccine candidate is especially encouraging as its stability at room temperature would facilitate cold chain free vaccine distribution around the world.
5) Oravax Medical Inc. COVID-19 Vaccine:
Oravax Inc. is the joint collaboration of Indian-Israeli Premas Biotech and Oramed pharmaceutical companies. Accelerating the vaccine’s path to market, trials on oral COVID-19 vaccines that can be potentially administered in a single dose orally are under process by the late phase of 2021 or early phase of 2022.
Mechanism of Action - After a single dose of the Oravax COVID-19 capsule, efficacy was evident through antibody production in a pilot animal study. Oravax vaccine promoted both systemic immunity through immunoglobulin G (IgG) (the most common antibody present in blood and bodily fluids that protect against viral infections) and immunoglobulin A (IgA), which protects the respiratory and gastrointestinal tracts against infection. Oravax’s COVID-19, which is a triple antigen virus-like particle (VLP), consists of 3 structural proteins of SARS-CoV-2, unlike most other vaccines that are based on spike (S) protein. This VLP technology, according to the company, is protective against the emerging mutations of the coronavirus.
Conclusion:
The oral delivery of COVID-19 vaccines can hence be helpful for wide-scale inoculation and easier distribution of the vaccine without requiring an injection. Evidence is also suggestive of the fact that oral COVID vaccines have not only promising potential but also accelerate herd immunity in the near future.
