Recent reports have raised concerns about rare side effects associated with AstraZeneca's Covid-19 vaccine, developed and manufactured as Covishield in India. For the first time, the pharma giant admitted that its vaccine can cause TTS—a severe condition resulting in low platelet count and blood clot formation. Experts say that while every vaccine has side effects, TTS is rare and was known to us before people were inoculated. Is there any reason to worry? Here's everything you should know