A new retrospective study, published in nature communications, recruited nearly 1.5 million adults from the Maccabi Healthcare Services in Israel. The population is characterized by adults older than 16 years, and receiving a second dose of the BioNTech/Pfizer mRNA vaccine between January and February (early vaccinees) and March-April (late vaccinees). The researchers compared the incidence of breakthrough infections between the two groups after adjusting for the underlying comorbidities and found a statistically significant difference. The early vaccinees had a 51% increased risk compared to the late group.
Read the study here.