Vulnerable people may need vaccine boosters this year, scientists say
新冠易感人群今年可能需要打疫苗加强针

Pfizer jab found to elicit lower antibody response to Delta variant than to original coronavirus strain
研究发现，BioNTech/辉瑞疫苗对首先在印度发现的新冠病毒Delta变体产生的抗体反应较低，易感人群可能需要打加强针。