Question to the Department of Health and Social Care:

To ask Her Majesty's Government how effective (1) an adenovirus vector, and (2) an mRNA, COVID-19 vaccine is if a person only receives one of the two doses required under the vaccination protocols.

The Joint Committee on Vaccination and Immunisation (JCVI) has recommended that as many people on the JCVI’s priority list as possible should be offered a first vaccine dose as the initial priority. One dose of the vaccine offers important protection and allows us to reach as many at risk people as possible in order to offer protection until the second dose can be administered. All individuals will subsequently receive a second dose in due course.

It can be assumed that protection from the first dose will require boosting in order to provide more durable protection. The JCVI supports a two-dose vaccine schedule for the Pfizer-BioNTech and AstraZeneca vaccines.