March 6: US scientists are skeptical of a one-shot regimen for Pfizer Inc and Moderna Inc Covid-19 vaccines, saying there isn’t enough evidence that a single dose provides long-term protection, the Wall Street Journal reported https://www.wsj.com/articles/u-s-scientists-skeptical-of-one-shot-regimen-for-pfizer-moderna-covid-vaccines-11615064919?mod=latest_headlines.