Pfizer announced Thursday that it is developing a booster shot to fight the highly contagious Delta variant of COVID-19 — as fears mount over the US’ most dominant strain, according to a report. The drug making firm and its partner, BioNTech, said adding a third jab to the two-dose vaccination could provide the “highest levels” of protection against all variants, including the Delta, CNBC reported. “As seen in real world evidence released from the Israel Ministry of Health, vaccine efficacy has declined six months post-vaccination, at the same time that the Delta variant is becoming the dominate variant in the...