COVID-19 vaccine is being extended once again, officials with the Middlesex-London Health Unit announced Tuesday.Starting Wednesday morning, residents age 12 and older who received their first vaccine dose on or before May 9 will be able to re-book their second-dose appointment.The announcement comes as local health officials anticipate the arrival of some 17,000 doses of the Moderna vaccine next week on top of the normal weekly Pfizer allotment of 25,000 doses.A similarly large Moderna shipment is also expected the week after, according to the health unit.“The additional vaccine that will arrive over the next two weeks will allow the Health Unit to expand and improve the efficiency of its vaccine rollout program, making it possible for.