"The emergence of new variants, which degrade the efficacy of some vaccines, only confirms the initial intuition behind the ACT-A initiative: This pandemic is being fought on a global scale, to the extent that our health security depends on the rapid access of poor countries to protective devices, tests, and vaccines. These are all bulwarks against the virus. International solidarity and health security go hand in hand, which is why, I have proposed the establishment of a mechanism for sharing doses with our African partners."

- Emmanuel Macron, President of France

Following its first outbreak in China in 2019, the COVID-19 pandemic has become the most serious global crisis that society is now facing. Multiple varieties of SARS-CoV-2 are produced as a result of the virus's continual mutation, although the majority of them share the same basic characteristics. All variants that have these main properties of the initial virus will be referred to as reference variants in this study. However, because of the virus's continual mutation, new variants with major differences in the virus's transmission characteristics, fatality rates, and other features may emerge, which will be referred to as new variants.

The different types of COVID-19 vaccines

Why is it that there are so many vaccinations in the works?

Before any vaccine candidate is confirmed to be both safe and efficacious, it is usually tested on a large number of people. For example, around 7 out of every 100 vaccinations examined in the lab and on laboratory animals will be regarded strong enough even to advance into human clinical trials. Only one in every five vaccinations that make it to clinical trials is successful. Having a large number of vaccines in research raises the likelihood of one or more successful vaccines being demonstrated to be safe and effective for the prioritised populations.


Various types of vaccines available till now

Vaccination can be designed in one of three ways. They vary in whether they use the whole virus or bacterium, simply the bits of the germ that activate the immune system, or just the genetic information that supplies the instructions for manufacturing certain proteins rather than the entire virus.

The whole-microbe approach

  • Inactivated vaccine

The first step in developing a vaccine is to inactivate or destroy the disease-carrying virus or bacteria, or one that is very similar to it, using chemicals, heat, or radiation. This method employs technology that has been shown to function in humans – such as the flu and polio vaccinations – and vaccines can be produced on a significant level.

However, it necessitates specialised laboratory equipment to safely develop the virus or bacterium, can take a very long time to produce, and will almost certainly involve two or three doses to be delivered.

  • Live-attenuated vaccine

A live-attenuated vaccination employs a virus that is still alive but has been weakened or one that is extremely similar. This type of vaccine includes the MMR (measles, mumps, and rubella) vaccine as well as the chickenpox and shingles vaccine. This method is based on the same technology as the inactivated vaccine and may be produced in large quantities. However, persons with weakened immune systems may not be able to benefit from such immunizations.

  • Viral vector vaccine

This form of vaccine employs a safe virus to effectively deliver sub-parts of the germ of interest, known as proteins, in order to elicit an immune response without causing the disease. The directions for producing specific portions of the pathogen of interest are introduced into a safe virus to accomplish this. After that, the virus acts as a medium or vector for delivering the proteins into the body. The immunological response is triggered by the protein. The Ebola vaccine is a viral vector vaccine, which means it can be made quickly.

  • The subunit approach

A subunit vaccination is one that only uses the bits of a virus or bacteria that the immune system needs to detect (the subunits). It doesn't employ a safe virus as a vector or contain the entire microorganism. Proteins or carbohydrates could be used as subunits. The majority of vaccinations on the paediatric immunisation schedule are subunit vaccines that protect against diseases like whooping cough, tetanus, diphtheria, and meningococcal meningitis.

The genetic approach (nucleic acid vaccine)

Unlike vaccines that use a full or parts of a weakened or dead microbe, a nucleic acid vaccine only uses a segment of genetic information that supplies the instructions for certain proteins, rather than the entire bacterium. Our cells employ DNA and RNA as instructions to produce proteins. DNA is converted to messenger RNA in our cells, which is then used as a blueprint to produce specific proteins.

A nucleic acid vaccine gives our cells particular instructions, either in the form of DNA or mRNA, to create the protein that we want our immune system to detect and respond to. The nucleic acid method is a novel technique for vaccine development. None had gone through the whole licencing procedure for use in people before the COVID-19 pandemic, though certain DNA vaccines, particularly those for specific tumours, were in human testing. Because of the pandemic, research in this field has accelerated, and several COVID-19 mRNA vaccines have received urgent use authorisation, meaning they can now be given to individuals outside of clinical trials.

Which vaccines have approval?

Vaccines are now available in a variety of countries. Vaccines must be approved by the Food and Drug Administration in the United States (FDA).

They must first pass three phases of tests to demonstrate that they are both safe and effective. The third and last stage, phase 3, involves tens of thousands of people.

Two vaccinations the FDA has approved Trusted Source for usage in the United States:

  1. the Pfizer-BioNTech COVID-19 vaccine
  2. the Moderna COVID-19 vaccine

On December 11, 2020, the Pfizer-BioNTech vaccine, which was formulated in Germany, gained FDA approval in the form of an emergency use authorization Trusted Source. In a phase 3 experiment involving almost 43,000 patients, half were given a placebo and the other half were given two doses of the vaccine separated by 21 days. The vaccine was 95 percent effective in protecting against COVID-19, according to the findings.

On December 18, the Moderna vaccine, developed in Cambridge, MA, was approved for emergency use in the United States Trusted Source. 30,000 volunteers were given a placebo or two doses of the vaccine 28 days apart in a phase 3 experiment. According to the findings, the vaccine was 94 percent effective.


Other vaccinations

Other vaccinations that have received approval in different countries include:

  1. The Oxford AstraZeneca vaccine, in the United Kingdom
  2. Coronavac, developed by Sinovac, in China
  3. The Sputnik V vaccine, in Russia
  4. Covaxin, developed by Bharat Biotech, in India

Meanwhile, both the Novavax and Janssen COVID-19 vaccines are undertaking phase 3 studies at the Trusted Source. Both were created in the United States by American firms. The Regulatory Affairs Professionals Society's COVID-19 vaccine tracker helps keep you up to date on the latest vaccine developments in the country.

Is it true that the vaccinations are safe?

Before a vaccine producer can request for clearance from a country's health authority, it must go through numerous steps of testing. The FDA grants this approval in the United States, and the Centers for Disease Control and Prevention (CDC) Trusted Source ensures public safety. Vaccine trials are including larger and larger groups of people. The final phase, phase 3, involves tens of thousands of people.

Any new medical treatment, along with a vaccine, has an unclear long-term effect at first. The objective is to weigh the hazards of taking a vaccine that has been thoroughly tested against the known dangers of contracting COVID-19. A person who has taken the COVID-19 vaccine may develop flu-like symptoms and other side effects in the relative phase, including:

  • pain at the injection site
  • swelling at the injection site
  • fatigue
  • headache and muscle pain 
  • a fever

Since the body's immunological reaction will be heightened after the second dose of the vaccination, the side effects may be harsher. The CDC recommends that consumers use V-safe Trusted Source, a smartphone-based health checker, to report any side effects to the authorities. This allows them to track the vaccine's impact and continue to work to maintain public safety.

It is critical to get the vaccine from a registered healthcare provider and to follow all instructions carefully, including getting a second dose. The vaccine is available at local health departments, hospitals, clinics, and pharmacies.

Anyone who has had an allergic reaction to vaccines or other injectable medications should inform the healthcare provider before the vaccine is given. Anyone who experiences an adverse response after receiving the vaccine should seek immediate medical attention.

COVID-19 immunisation reduces infection rates among healthcare workers, according to a UCI Health study. COVID-19 infection rates amongst healthcare staff at UCI Health were shown to be lower after getting the COVID-19 vaccine, according to research featured in JAMA Network. There were 133 million COVID-19 cases and 2.9 million fatalities worldwide by mid-April. Concerns about asymptomatic infection and spreading concerns in vaccinated people led UCI Health physicians to perform a performance improvement research to see if symptomatic and asymptomatic infections in healthcare staff (HCP) decreased after they received the COVID-19 vaccination.

According to, Dr. Shruti Gohil, UCI Health associate medical director for epidemiology and infection prevention, “Vaccines exist to curb disease transmission – yet there was a lot of skepticism around whether COVID-19 vaccination would be effective against silent spreaders of the disease.”

The 15-week study, which started in November 2020, looked at COVID-19 cases among UCI Health employees before and after vaccination. Every UCI Health HCP was checked for COVID-19 symptoms on a daily basis, which included a temperature check. Those who had COVID-19-related symptoms were given a quick COVID-19 test, while those who didn't have any symptoms were given a random COVID-19 test. Even though, infection rates in the community were high at the time of the trial, the vaccine's effectiveness was proven.

After the second dosages started, daily HCP instances dropped from 18 to 8 (55 percent reduction) after one week, 3 (84 percent reduction) after two weeks, and 1 (94 percent reduction) after three weeks. In a location with high incidence of COVID-19 disease nationally in the 2020-21 winter season, HCP immunisation resulted in a rapid and consistent decrease in both symptomatic and asymptomatic infections.

The predominant COVID-19 strain of the Delta Variant


Even as early as this summer, people began to have some hope—or at least cautious optimism—that the pandemic would fade into the backdrop, new mutations of the COVID-19 virus may bring it back, and it could be even stronger. Delta, a highly contagious SARS-CoV-2 virus strain initially found in India in December, is a serious concern right now. It spread quickly throughout that country and Great Britain before making its way to the United States, where it is today the most common variation.

In an internal document obtained by The New York Times and reported on, the Centers for Disease Control and Prevention (CDC) described Delta as more transmissible than the common cold and influenza, as well as the viruses that cause smallpox, MERS, SARS, and Ebola—and called it as contagious as chickenpox. The CDC reports that areas with low vaccination rates are seeing the most instances and severe outcomes, with unvaccinated people accounting for nearly all hospitalizations and deaths.

The Delta variant has various characteristics that we should be aware about

  • People who have not been vaccinated are at risk

The people who have not been properly vaccinated against COVID-19 are the ones who are the most vulnerable. In the United States, states with poor vaccination rates, such as Alabama, Arkansas, Georgia, Mississippi, Missouri, and West Virginia, have a disproportionate number of unvaccinated persons. (In some of these states, the number of instances is increasing, while in others, limits are being lifted since the number of cases is decreasing.) Children and teenagers are also a source of concern. According to Dr. Yildirim, “a recent study from the United Kingdom found that youngsters and individuals under the age of 50 were 2.5 times more likely to become infected with Delta.”

  • Delta could lead to 'hyperlocal outbreaks'

Dr. Wilson thinks the major questions will be about heightened transmissibility—how many people will catch the Delta variant and how quickly will it spread—if Delta continues to move fast enough to hasten the pandemic.

According to him, the answers could be influenced by where you reside and how many individuals in your area have been vaccinated. “I call it ‘patchwork vaccination,' where you have pockets of people who are well vaccinated next to those who are only 20 percent vaccinated,” Dr. Wilson explains. “The difficulty is that the virus can hop, skip, and jump from one inadequately vaccinated area to another as a result of this.”

  • A lot of research still to be discovered about Delta

The question of whether the Delta strain will make you sicker than the original virus is an essential one. Many scientists, on the other hand, believe they have no idea. A research from Scotland found that the Delta variant was roughly twice as likely as Alpha to cause hospitalisation in unvaccinated people, but other evidence has found no significant difference.

Another question concerns Delta's impact on the human body. Dr. Yildirim says there have been reports of symptoms that aren't the same as those connected with the initial coronavirus strain. “Cough and loss of smell appear to be less common. According to the most current surveys in the United Kingdom, where the Delta strain is responsible for more than 90% of infections, headache, sore throat, runny nose, and fever are all present.

Experts are beginning to gain a better understanding of Delta and breakthrough cases. At least two vaccines are effective against Delta, according to a Public Health England analysis (in a preprint that has not yet been peer-reviewed).

In the studies, the Pfizer-BioNTech vaccine was 88% effective against symptomatic disease and 96% effective against Delta hospitalisation, while the Oxford-AstraZeneca vaccine (which is not an mRNA vaccine and is not yet available in the United States) was 60% effective against symptomatic disease and 93% effective against hospitalisation. Participants in the research were completely immunised with both recommended dosages.


People who have been fully vaccinated against the coronavirus continue to have good protection against COVID-19, according to what we know so far. However, anybody who is unvaccinated and does not use preventive measures is at a significant risk of contracting the new form. It's crucial to have affordable access to safe and effective vaccines if the COVID-19 pandemic is to be stopped, so seeing so many vaccines being tested and developed is quite encouraging. WHO and its partners are working relentlessly to discover, manufacture, and distribute safe and effective vaccinations.

Safe and efficient vaccines are a game-changing strategy, but we must continue wearing masks, wash our hands, ensure proper ventilation indoors, and physically distance ourselves from crowds for the foreseeable future. Being vaccinated does not exempt us from exercising caution and putting ourselves and others at risk, especially because research into the extent to which vaccines protect not only against disease but also against infection and transmission is still underway. But it is immunisation, not vaccinations that will put an end to the epidemic. We must ensure that vaccines are distributed fairly and equally and that every country acquires them and is able to use them to safeguard its citizens, beginning with the most affected.

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