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These susceptible mutations ultimately generate unusual variants that let the virus to get away from the immune system even after the vaccine administration. The mutation that occurs to the viral genome leads to the antigenic shift and drift, and it keeps spreading from one population to the other. ] Until now, no particular treatment strategy has been demonstrated to be effective against the COVID‐19. As of July 9, 2021‐ 185,291,530 cumulative cases have been reported globally with 4,010,834 deaths as reported by the World Health Organization (WHO). The disease mainly spreads through the respiratory droplets from the infected person. The novel beta‐corona virus family member SARS‐CoV‐2 (severe acute respiratory syndrome coronavirus) is the causative agent for the pandemic COVID‐19.
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The effectiveness of the polysaccharide vaccine in young children was increased using conjugation of polysaccharides with proteins.Ģ. CORONA VIRUS DISEASE 2019 (COVID‐2019) PANDEMIC Another type of vaccine is inactivated toxins from toxin producing microbes. Some vaccines are developed from components of pathogens such as nucleic acid or from specific proteins or polysaccharides. The pathogenic organisms were inactivated using thermal or chemical methods. They are produced by attenuation by growing the disease causing organism under sub‐optimal conditions which lessen their disease causing ability. ] They generally comprise both the whole/entire disease causing organism and their active constituents that can induce immunogenic response. Vaccines are usually effective but rarely provide permanent or complete protection from infectious diseases.
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Passive immunity enables effective protection by products produced from humans and transferred to another human usually by injection but wanes within weeks, months, or by years. Usually this type of immunity lasts for many years or for a lifetime. The active immunity provides protection that are produced by the person's own immune system. Active and passive are the two basic mechanisms to acquire immunity. Generally immunity is indicated by the occurrence of antibody to a specific organism or closely related organism. The capability of the human body to distinguish and tolerate the indigenous material as self to the body and to recognize and eliminate the foreign material as non‐self referred as “immunity.” The ability to discriminate microbes as foreign substance by the immune system provides protection toward infectious diseases. ] The vaccines are normally administered in their liquid form by injection, rather than oral or intra‐nasal routes. Immunization is considered as the ultimate achievement to public health care system during 20 th century, according to the Centers for Disease Control and Prevention (CDC). Vaccines are considered as a biological preparation that has the ability to enhance immunity, for disease prevention (prophylactic vaccine) or for treatment (therapeutic vaccine). The term “vaccine” originated from Latin “ Variolae vaccinae” successively after Edward Jenner demonstrated the prevention of cowpox in 1798.