Covid 19 Vaccine

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Vaccines usually contain the same germs that cause the disease (for example, measles vaccine contains measles virus, and Hib vaccine contains Hib bacteria). But they have been either killed or weakened to the point that they do not make you sick. Some vaccines contain only a part of the disease germ.

A vaccine stimulates your immune system to produce antibodies, exactly like it would if you were exposed to the disease. After getting vaccinated, you develop immunity to that disease, without having to get the disease first. This is what makes vaccines such powerful medicine. Unlike most medicines, which treat or cure diseases, vaccines prevent them.
A two-dose Covid-19 experimental vaccine is designed to prompt the immune system to produce antibodies against a portion of the coronavirus “spike” protein, which the virus uses to bind to and enter the human cells. The vaccine uses messenger RNA (mRNA), a molecule critical for the virus to produce protein.
The Covid-19 coronavirus pandemic has highlighted the importance of immunization to our modern world, but the path to universal vaccination is neither simple nor cheap. 
Across the world, more than 100 Covid-19 vaccines are currently being developed, with one European pharmaceutical company predicting it could have one ready to go into production by the year-end. In China, where the outbreak was first reported, five vaccines are already being tested on humans, and a government body says at least one could be ready also by the end of the year.  
The speed with which researchers and pharmaceutical companies have responded to the coronavirus pandemic has been described as "unprecedented". The discovery and research phase for a vaccine is normally two-to-five years. In total, a vaccine can take more than 10 years to fully develop and could cost up to US$500 million.   
The US Centers for Disease Control and Prevention have asked public health officials in all the American states to be prepared to start distributing a Covid-19 vaccine as soon as possible. This push comes even before large-scale clinical trials of the candidate vaccines are finished. Data from these studies are needed to show whether the vaccines are safe and effective. Distributing a vaccine to millions of Americans in a short time is a vast undertaking that will require the coordination of many public health and other agencies, so an early start on planning will likely be needed. 
The excitement and enthusiasm for a Covid-19 vaccine by the end of 2020 is both palpable and understandable. We all hope for a rapid end to the pandemic and an effective vaccine would be a surefire solution. But there are risks that come with a fast-tracked vaccine delivered by the end of this year, not the least of which are the risks related to the safety of the vaccine itself.   
Telescoping testing timelines and approvals may expose all of us to unnecessary dangers related to the vaccine. While preclinical trials to evaluate the potential safety and efficacy of the vaccine candidates are likely to include tens of thousands of patients, it is still unclear whether that number will be large enough and a trial will last long enough to evaluate the safety for a drug that would be administered to so many. The US alone plans to vaccinate hundreds of millions of people with the first successful candidate vaccine. One serious adverse event per thousand of a vaccine given to 100 million people would mean harm to 100,000 otherwise healthy people.   
Aside from the questions of safety that concern any vaccine, there are good reasons to be especially cautious for Covid-19. Some vaccines worsen the consequences of infection rather than protect, a phenomenon called antibody-dependent enhancement (ADE). ADE has been observed in previous attempts to develop coronavirus vaccines. To add to the concern, antibodies typical of ADE are present in the blood of some Covid-19 patients. Such concerns are real. As recently as 2016, Dengvaxia, intended to protect children from the dengue virus, increased hospitalizations for children who received the vaccine.  
Questions also arise around the efficacy of a potential vaccine. The little we know of the current generation of Covid-19 vaccines raises serious questions regarding their ability to protect people from infection. We know all the candidates tested to date in non-human primates failed to protect any of the monkeys from infection of the nasal passages, the primary route of human infection. Failure to protect entirely from infection fits with all we know about attempts to protect monkeys from two other deadly coronaviruses, those that cause SARS and MERS.  
An effective Covid-19 vaccine also faces several hurdles beyond our control. The older we get the poorer our ability to respond to vaccines. Resistance to vaccination begins early at age 30 and becomes progressively more profound with time. That is especially troubling as those over 60 are the population most at risk. Vaccination of the elderly may sometimes succeed by administering repeated doses and by increasing the potency of the vaccine with powerful adjuvants. But these adjuvants can be especially risky for the very old. 
It seems a folly then to rush our way towards a vaccine in 2020 if it is likely to have only limited benefit to the population most in need and may put otherwise healthy people at risk. The risk goes far beyond the dangers a Covid-19 vaccine alone may hold. Public support for vaccines in general is already an issue. Trust in other lifesaving vaccines will be eroded even further if a Covid-19 vaccine goes wrong and many more people -the children and the elderly especially - could be at higher risk. 
Safety is just as important as efficacy. Clearly, the doctors need to ensure they are not causing harm, and any serious side-effect attributable to the vaccine would damage the reputation and significantly affect the take-up of the vaccine.
We have had around 56 million cases of Covid-19 worldwide with about 1.3 million death. We hope and pray that the soon-to-be approved vaccines are effective and devoid of any serious adverse effects.
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