Covid-19 Vaccine

                          Coronavirus Vaccine

                                              PKGhatak,MD

Coronavirus Vaccine.

There are several coronaviruses, but most of them are harmless to humans. The coronaviruses that cause human illnesses are mentioned below

The common cold:

80% of the common cold is due to Rhinoviruses. Various other viruses are also responsible for the common cold, among them are several coronaviruses. No effective vaccine for the common cold is on the horizon.

Influenza:

There are many similarities between influenza and COVID-19, including the viral structure. Though the influenza virus belongs to the Orthomyxovirus family. The yearly vaccine contains several strains of influenza viruses that are needed to protect against emerging mutants of the Influenza virus. The vaccines are made either in cell culture or in eggs, then killed, and the antigens are extracted. Influenza viruses undergo frequent mutations and the vaccine has to be modified every year. The immunity lasts only one year.

MERS (Middle Eastern Respiratory Syndrome):

MERS is due to a coronavirus. Between 2012 and 2019, about 2,500 people were infected with the MERS virus and 858 deaths were recorded. 80% of deaths took place in Saudi Arabia. No MERS vaccine has been produced to date.

SARS:

A local epidemic broke out in Guangdong province in China in 2002 – 2003. The virus had killed 778 people in 29 nations and infected 8,000 people. The virus is called SARS-CoV-1 and the disease SARS (severe acquired respiratory syndrome). A worldwide search for a vaccine was launched. But 18 years have passed without significant success.

COVID-19.

In December 2019, another coronavirus, SARS-CoV-2, began a murderous march. It began in Wuhan City of Hubei province of China. As of this date, this virus has killed 200,000 people and infected 3 million people worldwide, sparing only a few isolated islands.

Steps in vaccine development

Previous experience with the development of vaccines for coronavirus diseases is not particularly encouraging. No one can say when such a vaccine will be found. Finding a vaccine quickly can't be predicted.

What are the track records of Viral vaccine development:

Bacteria, one of the infectious agents, were first identified by Robert Koch in the 1800s, and he was also able to grow bacteria in agar in his laboratory.

In 1858, Louis Pasteur demonstrated that sterilization prevented fermentation of grapes into wine, a process that killed the yeast responsible for fermentation, and after that, the Spontaneous generation theory was thrown out.

In 1885, Louis Pasteur successfully treated a 9-year-old boy with Rabies with a vaccine he developed by repeatedly passing the rabies virus in the rabbit brain, thereby weakening its virulence but retaining its antigenicity.. He developed this method of attenuation of viruses between 1881 and 1885.

But he was not the first person to develop a vaccine to treat a viral illness. That distinction goes to Edward Jenner. In 1796, he took a sample of cowpox pus (Vaccinia is the name of the virus) and inoculated an 8-year-old boy and a few months later, inoculated him with the live smallpox virus (the virus is called Variola). The boy remained well and had no ill effects. It was slowly accepted in the medical community and subsequently, the vaccination was adopted by all advanced countries.

 Smallpox has been totally eliminated from the world by the tireless work of the WHO and others. The success of Jenner is an exception to the general rule. Cowpox and smallpox are related viruses and, fortunately, they carry the same antigen and the vaccine for cowpox also protects against smallpox. It must be mentioned that live viruses are not safe to introduce into the human body.

 Currently, the smallpox vaccine is made using a weakened virus grown in cell culture.

To honor Edward Jenner for his gift to humanity, Louis Pasteur called his invention the vaccine.

Other examples of success stories:
 

Take, for example, the Yellow Fever Vaccine.
In 1793, Philadelphia, Pennsylvania, saw a yellow fever epidemic that killed 5,000 people out of a population of only 50,000 at that time. In a panic, the city was practically abandoned.

Yellow fever killed more soldiers in the Spanish-American War of 1868 than in combat. During the construction of the Panama Canal in 1912, several thousand died. Dr. Max Theiler produced a vaccine after a continuous 30 years of trial from a weakened strain of the virus by 30 passages in the mouse brain.

Polio vaccine:

Salk's intramuscular polio vaccine is a product of a weakened strain of poliovirus, grown in monkey kidney cells and inactivated by formalin. It became available in 1954. It took him several years to develop a safe polio vaccine.

Sabin Oral Polio vaccine contains 3 strains of the polio virus, made safe by repeated passage through a primate and cultured in primate cells.

Failure stories:

HIV/AIDS:

HIV jumped from chimpanzees to humans in 1920. In the 1980s, it began to spread from Africa to other countries and became a great health risk for people all over the world. It has now been 30 years since the HIV/AIDS infection began. Fortunately, many safe and effective antiviral drugs can keep patients alive. Research began worldwide in the 1980s for an effective vaccine.  But no vaccine has been produced so far.

Dengue fever:

Though a vaccine was marketed in 2019 within a reasonably short period, however, the vaccine had to be withdrawn because, in post-vaccine patients who were re-infected with dengue, the symptoms were much more severe than in people who were not vaccinated.

The anthology of vaccines is full of stories of successes and failures. Many dedicated researchers and scientists put in countless hours of hard work and sleepless nights behind each vaccine production. The outcome of any research in the arena of biological systems is very unpredictable. In vaccine research, no one can dictate to the researchers to come up with a successful product in 5 months when, in actuality, it takes years, if not a lifetime.

Moderna Boston group.

They are using an engineered messenger RNA (mRNA). It induces viral protein in humans. That triggers antibody production. It is important to note that there is no previous mRNA vaccine produced by anyone that is approved for human use.

Chinese company Sinovac vaccine.

They are using an inactivated COVID-19 virus. This vaccine is safe for humans. The Chinese government has started inoculating its military personnel with this vaccine.

A recent report from India regarding antibody response to the COVID-19 virus infection or post-vaccine response shows that 14 % had no antibodies in blood when tested. The investigators commented that the timing of tests is important because the antibody levels fall in 2 to 3 weeks' time. So, the absence of antibodies does not mean that 14 % did not have antibodies at all.

  From Iceland, an opposite result is published. They used 6 different antibody tests, including two Pan Immunoglobulin (IgG, IgM, IgA) assays to document antibodies in COVID-19 recovered patients. Also, they used Quantitative Polymerase Chain Reaction(q-PCR) assays to identify COVID-19-infected patients. In their study, antibodies remain in the blood for 4 months. And 91 % of patients had antibodies for up to 4 months. The viral particle tests by PCR have fewer false-positive or false-negative results. Quantitative PCR eliminates positive test results. It appears Iceland investigators placed emphasis on finding antibodies by 6 tests and limited virus-positive tests by qualifying the quantity of virus present.

edited  June 2025.

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