The coronavirus vaccines, Covaxin and Covishield, have received a green signal for restricted emergency use in India. Indian central government first granted emergency use approval to Covishield and then to Covaxin.
COVID-19 is a disease caused by a new strain of Coronavirus, where "CO" stands for CORONA, "VI" stands for VIRUS, and "D" for DISEASE. SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is a unique strain of Coronavirus that has not been identified in humans earlier. The COVID-19 was behind the respiratory illness disorder first discovered in Wuhan, Hubei province, China, in December 2019. Since then, cases have been identified in almost all countries worldwide, and WHO declared it a pandemic on 11th March 2020.
Vaccines against the SARS-CoV-2 virus are known to produce antibodies that reduce the severity of the disease, symptoms, and spread of COVID-19. They are designed to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19). As COVID-19 vaccines have only been developed recently, it is early to determine the duration of protection offered by them. Researchers are still trying to establish this. But, initial data on recovered COVID-19 patients show an immune response that provides some period of protection against reinfection.
There is still a lot to learn about how strong and long this immunity lasts. Before the COVID‑19 pandemic, there was an established knowledge about coronaviruses' structure and function due to research on the other strains of Coronavirus causing the Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS). This quickened the development of various vaccines against COVID-19.
Covaxin is India's first homemade vaccine against COVID-19, which has shown high antibody response levels in a mid-stage trial. It has demonstrated 81% efficacy in preventing symptomatic COVID-19, based on an interim analysis of late-stage problems.
Bharat Biotech has produced this vaccine in collaboration with the ICMR (Indian Council of Medical Research) and the NIV (National Institute of Virology), Pune. Covaxin is an inactivated vaccine, meaning it contains killed SARS-CoV-2. This makes it safe to be injected to acquire immunity. The manufacturers used a sample of the Coronavirus, which was isolated by India's National Institute of Virology. When administered, our immune system starts producing antibodies against the dead or inactivated virus. In the event of a future infection with this virus, the body will already have the antibodies to fight off the Coronavirus. Covaxin is given in two doses, administered four weeks apart.
Covaxin is produced by chemically treating novel Coronavirus samples to prevent them from reproducing. The double-dose vaccine presented a significantly more powerful neutralizing antibody response in Phase II than in Phase I due to the variation in the dosing regimens that changed to a 4-week apart injection program from a 2-week course. But it also noted that the Phase II trial, which had 380 participants, joined a small number of people aged between 12–18 years and 55–65 years. Follow-on investigations are required to establish immunogenicity in children and older individuals. It also said that while the trial involved participants from over nine Indian states, the study group lacked ethnic and gender diversity.
The initial data from the phase III trial for Covaxin showed it to be 81% effective. In contrast, the Coronavirus vaccines from Moderna and Pfizer have promoted 90-95% efficacy. Covaxin has been examined on monkeys and hamsters, and the results have revealed that it provides enough immunity against the virus. However, in the absence of proper results, data is still a primary concern amongst various experts.
Covaxin is administered in two doses, and the second dose is injected at an interval of 4 to 6 weeks.
Side effects are generally rare. Side effects in most vaccinated persons are very mild malaise, mild fever. Rarely skin rashes, dizziness, swelling of the face and the throat, weakness, pain, increased heart rate, nausea and vomiting, difficulty in breathing, itching, and other allergic reactions can occur.
The confined version of the Oxford-AstraZeneca COVID-19 vaccine is called Covishield. Serum Institute of India, the world's biggest vaccine producer by volume, joined with the British-Swedish drugmaker to deliver 1 billion doses of its COVID-19 vaccine.
It uses the common cold virus from the chimpanzee. This weakened version encodes instructions for building proteins from the new Coronavirus to generate an immune response and prevent infection. Two doses of the vaccine, which were given in four weeks intervals, were initially believed to provide the best protection against COVID-19.
The scientists reported that the Oxford vaccine had an overall potency of 70% but could be around 90% effective when administered a half dose followed by a total dose a month later. According to the preliminary investigation, the vaccine seemed to be more than 80 % effective in preventing severe illness among older individuals. Therefore, Covishield is a highly effective vaccine over novel coronavirus.
Covishield has withstood testing in four countries with a demographically different population, thus guaranteeing that it is safe to be used. Covishield has an effectiveness of 70.42%, according to the Serum Institute of India's data. However, it is still weaker than the Coronavirus vaccines from Moderna and Pfizer.
This vaccine is also administered in two doses and the second dose at an interval of 6 to 8 weeks. Covisheild vaccine can be safely stored at temperatures between 2 and 8C.
Side effects are generally rare. Side effects in most vaccinated persons are very mild malaise, mild fever. Rarely the skin rashes and other allergic reactions occur. The side effects of the Covishield vaccine are tenderness, pain, joint pain or muscle ache, generally feeling unwell, warmth, fatigue, redness, chills, itching, headache, swelling, nausea or bruising where the injection is given, feeling dizzy, enlarged lymph nodes, decreased appetite, excessive sweating, itchy skin, a lump at the injection site, flu-like symptoms.
Both the COVID-19 vaccines have some similarities and differences.
Covaxin is an inactivated vaccine, and it has been around for decades. It is based on a tried and tested platform of dead viruses. The vaccine uses whole-virion inactivated Vero cell-derived platform technology. The inactivated vaccines do not reproduce or replicate, so they do not cause any pathological effects. Covaxin also seems to have a distinct safety assurance with the lack of anaphylaxis. Numerous vaccines for diseases, such as influenza, rabies, pertussis, Japanese encephalitis, and polio, apply the same technology to develop inactivated vaccines. Covaxin has been recommended in India and Zimbabwe so far. Also, millions of doses have been used in India and Europe without any significant concern.
Covishield is a viral vector platform. The coronavirus spike protein is carried into human cells by the vector chimpanzee adenovirus called ChAdOx1. Covishield is harmless and starts fighting against similar viruses when the body provides manual instruction. Two transverse myelitis cases in the UK had stalled the clinical trial for the Covishield vaccine some time, but the trial resumed once the safety was confirmed.
Vaccination produces antibodies and helps reduce the severity of the disease, thus reducing the spread of COVID-19. Therefore, the general public should come forward to get vaccinated, use masks, maintain social distance, and save themselves from this COVID-19 pandemic.
Last reviewed at:
13 Apr 2021 - 4 min read
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