How COVID-19 Vaccine Works

How does the COVID-19 vaccines work? What happens during the vaccination? Is it safe? Can I get vaccinated without medical examination?


The coronavirus disease 2019 (COVID-19 Virus) has claimed thousands of lives worldwide and infected millions. Although vaccines against the COVID-19 virus are being developed for Clinical Trials and started vaccinated.




Vaccination helps prevent illness from infectious diseases. When people are exposed to the virus, their bodies produce antibodies that fight off the infection. If someone has already got the COVID-19 virus, the body or human cells are able to produce immunity against future exposure.


According to a recent study published in The Lancet Infectious Diseases journal by scientists at the University of Oxford, there will be an effective vaccine available within 12-18 months . However, such studies would need to take into account the level of risk involved in receiving such a shot.


Scientists believe the development of a COVID-19 vaccines after Clinical Trials could prove challenging given the nature of this novel coronavirus. It appears as if the new coronavirus attaches itself firmly to cells and spreads easily between them, causing deadly infections. While viruses like influenza can mutate rapidly, meaning new strains don’t cause much harm, the SARS-CoV-2 virus seems more stable than its predecessors.


So far, researchers have identified two potential targets:

• Spike proteins on the surface of the virus. These spike proteins bind onto ACE-2 receptors on cell surfaces, allowing the virus to enter cells. Scientists suspect these spike proteins may be an important source of genetic variation for immune system recognition.


• Nucleocapsid protein inside the virus which plays a role in viral replication. The nucleocapsid protects RNA strands carrying the gene codes needed for making copies of the virus. This part of the genome tends to accumulate mutations during transmission, suggesting it could also be used as target.


Researchers hope to develop a viral vector vaccine using either or both of these components. But what exactly do we know about how vaccines work? Here are some answers to common questions that you might have on this topic:


How does a COVID-19 vaccine work?


COVID-19 Vaccine component contain tiny amounts of antigens, usually proteins or chemicals made by bacteria or other organisms. These foreign substances stimulate the immune system to help protect people from getting sick from diseases. Once injected with a vaccine, your immune system responds by producing antibodies – molecules produced by white blood cells that circulate through the bloodstream and alert immune cells when they recognize something harmful.


When the pathogen enters our body, these antibodies attach themselves to it so that immune system cells can identify and destroy it.


Immunization refers to giving out small doses of a particular antigen, thus stimulating the production of antibody against that antigen. Giving multiple booster dose of vaccines boosts the production of protective antibodies.


Can vaccines make me sick?


Short answer: No!

However, there are very rare cases where people react abnormally after being vaccinated. These reactions are called adverse events following immunization (AEFI). They happen because the immune system recognizes certain vaccines, including live attenuated ones, as “foreign bodies” and attacks them. When this happens, your body releases cytokines, which is a type of chemical messenger. AEFIs are not caused by all vaccinations. Most of them occur within 24 hours after immunization and disappear within 2 weeks. If symptoms last longer than 7 days, call your doctor immediately. Serious side effects are extremely rare, but possible.


What are adjuvants?


Adjuvants are additives that enhance the efficacy of vaccines. Some of them function by increasing the amount of antigens delivered to the lymph nodes to trigger a stronger immune response. Others encourage immune system cells to differentiate into long lasting memory cells and kill intruding pathogens even if your immunity has weakened.


Why should I get vaccinated?


You may already know that COVID-19 vaccination reduces death and disease from infectious illnesses. Every year, millions of people die from preventable bacterial infections such as pneumonia and influenza. In addition, diseases like measles and diphtheria still cause thousands of deaths across the world every year. Millions more suffer paralysis, blindness, brain damage, infertility and emotional disorders due to these diseases. Your chances of contracting one of these deadly diseases can be reduced dramatically by vaccination. However, many countries have had high rates of infection from vaccine-preventable diseases for years. The main reason why developing nations have poorer health outcomes is poor access to healthcare services.

The current state in India is alarming. Over the past few decades, India has witnessed substantial economic growth; however, its child mortality rate has been constantly rising since 1980. This is largely contributed to poor sanitation and hygiene conditions especially in rural areas. According to 2015 National Family Health Survey data, 63% of children under 5 years old did not receive recommended vaccinations.


Vaccination is an important tool to ensure healthy lifestyles in the future. That is why WHO recommends MRNA Vaccines for vaccination for both adults and young children to achieve the highest impact on reducing infection risks. WHO also advocates routine childhood vaccination programs so that coverage becomes universal by 2025. For example, over 90% coverage is achieved now in some regions. However, India does not yet follow these recommendations fully. It only administers three core vaccines – DPT/HepB/polio – during the first 1½ years of life. As of June 2019, only about 50% of children aged 12-23 months received all 3 doses including booster dose at the same time. Only 27% of infants were administered with BCG in 2017–2018.


There are several reasons why vaccination needs improvement:


1. Lack of infrastructure: Vaccination requires cold chain storage and administration. Many low-income and middle-income countries don’t possess sufficient equipment or trained human resources to administer vaccines safely and effectively. As a result, some parents opt out of vaccinating their children.

2. Poor awareness: Many parents are unaware of the benefits of vaccination and cannot decide whether it is necessary. In addition, they often believe that adverse effects outweigh the potential benefits. They may think they will face discrimination if they ask about vaccinations at government agencies or hospitals. These myths undermine the efforts made by public education campaigns to increase awareness of vaccination.

3. Negligence: Some doctors are negligent when administering vaccines. There are cases where doctors failed to provide full information before vaccinations. They might not disclose possible side effects because they want to avoid criticism from patients. Doctors are even known to falsify medical records and take money for unnecessary procedures.

4. Misinformation: Public media plays a major role in spreading misinformation regarding immunisation. Most parents do not trust TV advertisements promoting anti-vaccine messages. Parents tend to rely on other sources of information such as personal experience and friends instead.

5. Ineffective Communication: Even though vaccination is free in most places, many parents are reluctant to visit clinics and hospitals. With limited communication channels, they may choose to stay home rather than go to the nearest clinic. They may also have problems understanding health promotion messages sent by officials through social media platforms.

6. Noncompliance: Sometimes, people fail to comply with vaccine schedules because of lack of motivation or lack of access to healthcare facilities. People may also neglect vaccination due to lack of knowledge or mistrust of vaccination. This can be particularly true in rural areas. When a child misses a scheduled vaccination, he or she is more likely to develop severe illness compared to those who receive timely treatment.

7. Fear of Vaccines: The concept of vaccination has been tarnished by stories of adverse reactions following certain vaccines. Some parents worry about the safety of the vaccines being used today. To address this concern, we need to continue monitoring any existing issues related to vaccine safety and work harder to improve overall vaccine quality. If there should be an outbreak of a new disease, we must ensure that all available tools – safe and effective ones -are prioritized first.


If we look back on past pandemics, we find that in some countries the mortality rate was higher than others. For example, it was estimated that during the Spanish flu (1890s), 25% of the world population died while only one third survived in Sweden . However, China had lower mortality rates but experienced a shorter period until recovery - six months versus two years in the other countries. Based on these data, we can conclude that death rates depend on the intensity of virus transmission and speed of recovery.



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