COVID-19 vaccine’s effectiveness weeks after its first injection is piling up, Canada’s top public health official says.On Tuesday, Dr.
Theresa Tam called the figures “incredible,” and said “over two months of data and beyond” showed sustained efficacy among COVID-19 vaccines even after a “significant number of weeks.”The news comes as provinces and territories grapple with whether to lengthen the window between first and second shots.Tam’s comments echo a number of studies that have emerged over the last few months that experts have pointed to as justification to delay the second dose in an attempt to reach herd immunity faster.