positive on 18Mar2021 from one of the routine tests/ she took a rapid test, which also came back positive/ no symptoms; positive on 18Mar2021 from one of the routine tests/ she took a rapid test, which also came back positive/ no symptoms; This is a spontaneous report from a non-contactable consumer. This consumer (patient) reported similar events for four patients. This is the first of four reports.   A 27-year-old female patient (home health worker) received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE; lot number and expiry date: unknown), dose 1 via an unspecified route of administration on an unspecified date as single dose, dose 2 via an unspecified route of administration on 12Jan2021 as single dose for COVID-19 immunization. The patient medical history and concomitant medications were not reported.  Vaccinated Health Worker Tests Positive for COVID. It was stated that "breakthrough" cases of COVID-19 are popping up. They're people who test positive 14 days or more after receiving their last dose of the vaccine. It was stated that it is still shocking that the patient was positive. She have no symptoms. The patient's vaccination card shows she received her second dose of the Pfizer vaccine on 12Jan2021. She said she found out she was positive on 18Mar2021 from one of the routine tests she takes weekly for work. Believing it might be a false positive, she took a rapid test, which also came back positive. She said her mother and two other family members, all fully vaccinated, also tested positive this week. They were experiencing symptoms. The patient asked if the vaccine was still effective in her system. Dr., an associate professor of medicine, said it would be very unlikely that immunity would have worn off already. "When we have millions and millions of doses of the vaccine going out, there are always some rare cases where we see something that we don't expect," the Dr. said. He explained that vaccine trials based efficacy rates on symptomatic cases but didn't look for asymptomatic ones. There aren't many vaccines in general that offer what's referred to as "sterilizing immunity," or complete protection against viral infection. Most work to build up the immune system against a disease so that the next time we encounter it, our bodies can quickly fight it off. "People who are a little bit elderly, the whole point is to prevent people from going to the hospital, from dying from this virus," he said. In addition to media reports of breakthrough cases in (place name) outside (place name), the Health Department released an advisory earlier this month saying it was investigating instances in that state. It's asking health care providers to report breakthrough cases so that it can look into them further, along with the Centers for Disease Control and Prevention. The Health Authority announced last month it was also investigating breakthrough cases. "Such cases are not unexpected. Clinical trials of both vaccines presently in use included breakthrough cases," Health Authority wrote in a Facebook post made before the Johnson & Johnson vaccine became the third available option. The patient is currently isolating. She said she was told by the health department that she can resume normal activities on 25Mar2021, as long as she's not experiencing symptoms. The patient thought she just want people to continue to educate themselves about the vaccine and what's best for them and their family. She was still happy that she got it, but she really would like there to be more research on the effectiveness. Studies are currently ongoing on the Pfizer, Moderna, and Johnson & Johnson vaccines. These things will happen, and they will happen at some rate. But just to reiterate, the vaccines are very effective at what they're meant to do, which is to block symptomatic, and especially severe, COVID, they said. The outcome of the event was unknown.  Information on the lot/batch number has been requested.; Sender's Comments: Linked Report(s) : US-PFIZER INC-2021308941 same reporter/drug, different patient, similar events.;US-PFIZER INC-2021308943 same reporter/drug, different patient, similar events.;US-PFIZER INC-2021308942 same reporter/drug, different patient, similar events