Covid19 is a pandemic. When it started there was no information about it to the general public or even the medical community. There was no effective medicine to cure the infection. It was identified that the Covid infection is caused by a virus of the Corona virus family.The medical fraternity, with whatever little they know about the previous SARS virus attack caused by the Corona virus, experimented with trial and error type treatment.
the infection being caused by a virus, the only effective way to prevent was by developing a vaccine. But vaccine development is not a one day's job.It would take many years. Waiting for such long would have eliminated the majority of human species. So everywhere the research was being speeded up and governments and medical fraternity were read to take some calculated risk in order to curtail fatalities.
Thanks to the research scientists and medical fraternity and volunteers, a few vaccines were developed and found to be of some effectiveness. Some of the standard procedures followed till day in vaccine release had to be curtained and shortcut due to emergency situation,
So as of now there are only a handful of vaccines against Covid 19. They are in use for past few months. From the experience gained by their till day use, the research scientists ,pharma accompanies and governments and medical personnel feel they are effective inoculations.
As the vaccines are not widely available everywhere, and only some specific brans or names are available at each areas, people do not have much choice. They have to choose from a few handful names. Almost all of them are equal in their effectiveness.
The vaccines were till now used only in adults eighteen years and above. Research and trials are going on for those below i8 years. One or two countries reportedly have just started using it for older children.
Hence instead of waiting for a particular brand of vaccine, your priority should be to get vaccinated with whatever brand vaccine is permitted and available at your place. It should be ensured that the same brand is used for the booster dose if any. It is better to use the one which was mostly used in your country or place and is in use for past many months.
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Sputnik or covaxin or covishield- for more in this regard.