Shares of three leading COVID-19 vaccine makers sank on Thursday. As of the market close, BioNTech (NASDAQ:BNTX) stock was down 8.8%. Shares of Moderna (NASDAQ:MRNA) and Novavax (NASDAQ:NVAX) fell 5.8% and 4.2%, respectively.
None of the companies announced any developments. However, there were a couple of stories that were likely related to the vaccine stocks sinking.
CNBC reported that some scientists are criticizing the U.S. government’s decision to move forward with third booster doses of messenger RNA (mRNA) vaccines as premature. Also, results from a large U.K. study were published online. Those results showed that the effectiveness against the delta variant for the COVID-19 vaccines developed by Pfizer (NYSE:PFE) and BioNTech and by AstraZeneca falls off quickly.