Scientists worry whether COVID-19 vaccine will make a difference with 51 percent saying won't take

'Operation Warp Speed' aims to deliver 300 million doses of a vaccine to Americans by January 2021. Hundreds of vaccines are in the pre-clinical testing phase, but only four are currently in Phase 3 clinical trials and some of them have run into problems. More than half of Americans in a recent poll say they won't get a shot High-profile personalities such as Elon Musk have also said they will not be taking the vaccine. It has fed the growth of the anti-vaxxer movement with many deciding not to take the jab along political party lines. Scientists worry that if fewer than 70 percent of the population receive the injection, herd immunity will not be reached and its effectiveness will be lost