RECEIVED HALF DOSE FOR THEIR BOOSTER DOSE; OFF LABEL USE; This spontaneous report received from a health care professional concerned a 54 year old adult female of unspecified race and ethnicity. The patient's height, and weight were not reported. No past medical history or concurrent conditions were reported. The patient was previously received covid-19 vaccine ad26. cov2..s (suspension for injection, route of admin not reported, batch number: unknown expiry: unknown ) dose was not reported, 1 total administered for prophylactic vaccination (manufacturer unspecified, Dose number in series 1). No known events were reported after vaccination (dose number in series 1) The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: 211A21A (batch/lot number also reported as 1822809) expiry: unknown) dose was not reported,1 total administered on 27-NOV-2021 for prophylactic vaccination (Dose number in series 2). No concomitant medications were reported. On 27-NOV-2021, the patient received half dose for booster dose (captured as: vaccine underdose) and off label use (dose number in series 2). As reported by the investigator, HCP (health care provider) (from health dept) stated that there were 33 patients who received half doses (0.25ml (milliliter)) for their booster or 3rd dose a few days ago. Most of them were patients from Texas. HCP stated that something was printed and disseminated that said to administer .25ml. HCP was not sure where that information came from. Stated it was over the holidays so people could have thought that info changed and staff was just not made aware. HCP did not think it had been reported yet through VAERS. HCP thought that the vendor will file the report with agency, not public health department. HCP stated that they figured it out after the event because they could not figure out how so many doses were given. They were looking for a discrepancy in the number of vials perhaps, but then realized that half doses were given. HCP consented to being contacted, but stated that she may not be the best person to contact. If she had an alternate contact she would provide it to whomever reached out to her. The reporter went on to report that HCP stated that Spartan is the vendor. At the time of the discussion they were both teaming up together to gather information and they may have called to report these events as well, so HCP warned to be mindful of possible duplicate reports.  The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The outcome of the received half dose for their booster dose and off label use was not reported. This report was non-serious. This case, from the same reporter is linked to 20211165041, 20211200675, 20211200717, 20211200723, 20211200752, 20211200769, 20211200994, 20211201046, 20211201168, 20211201179, 20211201228, 20211201286, 20211201304, 20211201351, 20211201362, 20211201392, 20211201443, 20211201450, 20211201963, 20211202199, 20211202207, 20211202246, 20211202371, 20211202379, 20211165041, 20211202193, 20211202469, 20211204104, 20211220146, 20211220262, 20211220250, 20211220145, 20211220619, 20211220129, 20211219871, 20211220152, 20211202161, 20211201082, 20211202515 and 20211201082.