Science and health experts are bullish on the news about the Pfizer and BioNTech coronavirus vaccine candidate.The main reason for the excitement is the vaccine looks like it's on pace to fly right past the Food and Drug Administration's 50 percent efficacy threshold, according to its interim analysis, which pegged the rate at 90 percent so far. There's more good news between the lines, though -- the companies say they haven't observed any safety concerns among trial volunteers, the immune response should last for up to a year, and it's unlikely any mutations would be able to overcome the immune response.> this is one very positive line from the vaccine news https://t.co/YfzQSV7BS8 pic.twitter.com/J0vMOjo72m> > -- Tony Tassell (@TonyTassell) November 9, 2020The analysis looks promising for Pfizer's competitors, as well, since many other candidates are targeting the same protein on the virus. Plus, if the technology behind the vaccine is successful against COVID-19, it could open a realm of possibilities for vaccine development, at large.> 2\. It is also a really promising sign for the multiple other Covid19 vaccines coming up behind Pfizer, as this statement from @CEPIvaccines points out. They all target the same protein on the SARSCoV2 virus. Looks like it is a solid approach. pic.twitter.com/AoSVK9KBHm> > -- Helen Branswell (@HelenBranswell) November 9, 2020> That said, there are reasons to temper expectations, which, after all, are based on a press release. The 90 percent efficacy rate could drop as the trial continues (additionally, safety concerns could arise and the questions about immunity length and mutation protection remain open-ended), and there's also a lack of clarity about whether the vaccine may protect against the most severe COVID-19 cases and whether it protects elderly people. > Some quick thoughts re: Pfizer vaccine news: > \- Far better results than expected > \- So far just a press release, eager to see data > \- Want to see: results in elderly, impact on *severe* COVID19 > \- Looking forward to FDA adcomm > \- Overall: cautiously optimistic!> > -- Caroline Chen (@CarolineYLChen) November 9, 2020More stories from theweek.com Does it matter if Donald Trump never concedes? Trump will reportedly start reading obituaries of dead people who almost certainly didn't vote Ben Carson, who attended Trump's election party, tests positive for COVID-19