A Partial Vaccine Roll Out?

Some good news as the Oxford/AstraZeneca vaccine (which is said to be being made available at cost price), has been approved by the UK's Medicines and Healthcare products Regulatory Authority for roll-out here (https://www.theguardian.com/society/2020/dec/30/oxford-astrazeneca-covid-vaccine-approved-by-uk-regulator). Although it has been tested on fewer people and seems less effective than the Pfiser/BioNTech vaccine, it does have the advantage of being stable in standard refrigeration units. It should, consequently, be much easier to get it into care homes and for it to be dispensed by General Practioner services. The roll out (focusing initially on vulnerable groups), is due to start on Monday 4th January 2021. I am somewhat concerned by the decision to concentrate on giving 1st injections as widely as possible. Second injections will be given but will have a lower priority. I am not certain how much protection (and for how long) you get with a single jab. There is a report of a male Californian nurse, who had received a 1st injection of the Pfiser/BioNTech vaccine, testing positive for Covid-19, one week later. He would have been likely to have been exposed to high viral doses in his place of work and protection (only 50% for the initial jab) takes several days to be established. It is interesting (and somewhat worrying in terms of wider protections) that the European Medical Authority (dealing with the EU), claim to have, not yet, been provided with data relating to the Oxford/AstraZeneca vaccine. They are consequently not in a position to start the approval process for this vaccine in the EU. We really need to hit the virus as widely as possible and that includes in neighbouring countries.