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Since the nineteenth century vaccination has proved its importance. It has prevented infectious diseases, prevented people dying from those diseases and even eradicated some. But "no vaccine can be 100% safe or effective for everyone", cautions Dr Dawood Oars in this article adding " each individual responds in a different way depending on age, genetic and racial disposition, health conditions and whether suffering from other co-morbidities or severe diseases".
WHAT IS VACCINATION
Vaccination is the process of administration of a vaccine to help the immune system, a defensive system of the body, to develop immunity from a disease. Vaccines contain a microorganism or a virus, either in a weakened, live or killed state, or the proteins and toxins derived from them. Vaccination is the most effective method of preventing infectious diseases.
The first smallpox vaccine was invented in 1796 by the English physician Edward Jenner. Smallpox was a contagious and deadly disease at that time, by its disfiguring presentation and by its lethal complications leading to death. The concept of vaccination was furthered by Louis Pasteur later, and the value and importance of vaccination can be understood by the eradication of this disease in 1979.
Most vaccines are administered before a patient contracts the disease to help increase further protection. It provides a lasting protection, but it takes weeks to develop the immunity.
Most of the vaccines are given by intramuscular injections, but there are some given orally to produce immunity in the alimentary tract.
DEVELOPMENT OF VACCINES
No vaccine can be 100% safe or effective for everyone because each person's body does not react in the same way. Each individual responds in a different way depending on age, its genetic and racial disposition, its actual health conditions and whether he is suffering from other co-morbidities or severe diseases. Minor side effects can happen with a minority of people, and these can include local soreness, low grade fever or mild weakness. Serious side effects are very rare as each vaccine undergoes rigorous clinical trials to ensure their safety and efficacy before approval for use.
A first phase of testing is carried extensively on animals to determine various effects of the vaccine. Three phases of human testing are then allowed, first on twenty people, then fifty people, and then on hundreds and thousands of volunteers to follow up and study the effects of safety and efficacy. After successful trials, a licence for production and use is approved by the FDA, a body in the United States of America that continues to monitor the safety and efficacy of the vaccines.
A COVID-19 vaccine is intended to provide acquired immunity against SARS-CoV-2, the virus that causes the coronavirus disease (COVID-19). Some forms of vaccines were tried for previous corona viruses that were localized, but universal vaccines need to be developed after COVID-19 disease was declared a pandemic disease by the WHO. Various vaccine platforms were accelerated during early 2020. Many countries encouraged big pharmaceutical firms to produce the COVID-19 vaccines, as these vaccines would be the saviour as they were credited with the roles in reducing the severity and death caused by the COVID-19 disease. Prior to the COVID-19 pandemic, a vaccine for an infectious disease takes several years to be produced, but in this case an Emergency Use Authorisation was approved by many countries.
Most of the platforms of vaccine candidates in clinical trial are focused on the coronavirus spike protein (S protein) and its variants as the primary antigen of cOVID-19 infection since it triggers strong B-cell and T-cell immune responses. In 2020, platforms involved nucleic acid technologies (nucleoside-modified messenger RNA and DNA), live attenuated viruses and inactivated viruses.
Pfizer and Moderna vaccines use RNA to stimulate an immune response: the vaccine contains self-replication. RNA or messenger RNA (Myrna), which both cause cells to express the S-spike protein. The RNA vaccines were the first COVID-19 vaccines to be authorized in the United Kingdom, the U.S.A., and the European countries.
The non-replicating viral vector vaccines, such as AstraZeneca, Sputnik and Janssen, a one-shot vaccine, did not need huge storing facilities and could be stored under ordinary refrigeration. Inactivated vaccines consist of virus particles that are grown in culture, and then killed using heat or formaldehyde.
These vaccines include Sinopharm and COVAX in. Intranasal vaccines are being developed and these vaccines target the mucosal immunity in the nose, the portal of viral entrance.
The Pfizer-Boon Tech partnership submitted an Emergency Use Authorisation (EUA) to FDA for the Myrna vaccines on 20 November 2020. On 2 December 2020, the U.K Medicines and Healthcare products Regulatory Agency (MHRA) gave temporary regulatory approval for Pfizer vaccines. A week later, they granted an EUA for Moderna vaccines.
According to studies, the mix and match, a combination of two different COVID-19 vaccines, also called cross-vaccination, provide protection equivalent to Mrna vaccines, including protection against the Delta variant.
The duration of immunity is unclear because of many factors in the individual, though for those fully vaccinated or with previous infection, the risk of subsequent infection is very low for at least six months.
As at 23 February 2022, 10.65 billion COVID-19 vaccine doses have been administered worldwide, with 62.6% of the global population having received at least one dose. The World Health Organisation had put a target of vaccination for at least 40% of the population by end of 2021, a target they have not been able to achieve. Now, they have put a target of vaccinating at least 70% of the global population by mid-2022. The insular and rich countries have a high level of vaccinated people compared to poorer countries, mostly in African countries.
COVID-19 VACCINATION IN MAURITIUS
In Mauritius, the first vaccination program was launched on 26 January 2021, giving priority to front liners including healthcare professionals, senior citizens with underlying medical conditions, and those employed in the Tourism industry.
Following sequential tests, the initial forms of virus were seen to be contagious, and deadly especially for senior citizens with comorbidities like those undergoing dialysis. Then, we started getting variants of the virus, like alpha, beta and delta variants.
The latter was a lethal variant where the percentage of dying patients was much higher. 10.65 billion COVID-19 vaccine doses have been administered worldwide.
On 18 March 2020, three cases of COVID were confirmed. A lockdown was imposed on and this lasted till June 2020, undergoing mar on its passage. There was a calm period during infection March 2020 oddifications and December 2020, with new cases appearing later.
After receiving 100,000 doses as a donation from India, the Covishield vaccines were first used. Later, we received Covax-in, Sinopharm, Sputnik, Pfizer and Moderna. The front liners received first doses, as decided by the Vaccination Committee, followed by adults, the adolescents and even the children.
After the inoculation of the first dose, a second dose was advocated, especially after the emergence of the delta variant.Secondly, the efficacy of the vaccines was shown to go down after infection with the delta variant, sometimes by even 40%.
The duration of the acquired immunity was also questioned, and later, a booster dose was recommended.
Initially, the Ministry of Health arranged many centres around the Island for the public to be vaccinated. The private Clinics also showed interest to vaccinate public who desired to pay a small administrative fees upon receiving an appointment.
As on 24 February 2022, the level of vaccines in Mauritius is as follows:
First dose: 997,525
Two doses: 959,275
Fully vaccinated (Booster): 485,546
In Mauritius, 78% of the population has received at least two doses. The Government and professionals are urging the public to get administered with the Booster dose, for their own protection, and for the protection of their near ones.
Vaccination has since its advent in early nineteenth century proved is importance in preventing infectious diseases, and preventing people dying from these diseases, and even bringing the eradication of some of these diseases. Misinformation and disinformation do a lot of harm in public, and I recommend the public to contact health professionals for advice.
Dr Dawood Oaris, ENT Consultant
Professor Emeritus, Head of Department,
SSR Medical College
President, Private Clinics Association
Source : Discover & Invest Issue 21