first dose of the meningitis vaccine at age of 19 (Aug2019) and the second dose at age of 20 (Jul2020); bad rash around the insertion site/ huge rash; hives on the arm; Feeling bad; she had a severe allergic reaction to a meningococcal B vaccine; Mononucleosis; She had splenomegaly and hepatomegaly because of Mono; full body weakness; This is a spontaneous report from a contactable healthcare professional (patient). A 19-year-old female patient received first dose of meningococcal group b rlp2086 (manufacturer unknown, anatomical location of administration: left deltoid both times, lot number and expiration date were not reported), via an unspecified route of administration in Aug2019 at the age of 19 and second dose in Jul2020 at the age of 20, both at a single dose as meningitis vaccine. Medical history included thalassemia that was diagnosed early on in life prior to receiving the meningitis vaccine. The patient's concomitant medications were not reported. The patient had a severe allergic reaction to a meningococcal B vaccine on an unspecified date but she was not sure which brand of vaccine she received. She was asking if any ingredients are the same in the COVID-19 vaccine and if it would be safe to take the COVID-19 vaccine. She had a bad reaction to both doses of the meningitis vaccine and has Thalassemia. She had her first dose of the meningitis vaccine at age 19 and the second dose at age 20. When she got the first dose, she had a diagnosis of mononucleosis. She didn't realize it was the vaccine at first. She thought it was a complication from "mono". She had a really bad headache that lasted for a couple of days. She had full body fatigue and full body weakness. She didn't have any other diagnoses when she took the second dose. She had a really bad rash around the insertion site. She had hives on the arm, headaches and fatigue. She had to go to the emergency room for it because it was so frightening. She was not hospitalized and was discharged from the emergency room. The second one was given in Jul2020 at around 8AM or 9AM. Thalassemia was diagnosed early on in life prior to receiving the meningitis vaccine. It was also reported that the patient had splenomegaly and hepatomegaly because of "Mono", so she was taking a low dose of hydrocodone to help with pain. She was not on any other medication at the time she received the vaccine. When she had Mono in 2019 they did a complete CBC and her WBC was 17,000, so it was pretty high. They didn't do any pain blood work this year (2020). They had ruled it out as an allergic reaction. They had done a hematocrit and hemoglobin and it was normal. It was further reported that around noon after receiving the second dose, she started feeling bad. She had long sleeves on and wasn't looking at the arm. When she got out the shower the next day, her mom noticed her arm. It was a huge rash. She doesn't know if the rash was there before or not. She had her influenza vaccine after that by a couple of weeks. She was worried to have another reaction. She had no prior vaccinations within 4 weeks. Outcome of the events was unknown.  Pfizer is a marketing authorization holder of meningococcal group B Rlp2086 in the country of incidence or the country where the product was purchased (in different). This may be a duplicate report if another marketing authorization holder of meningococcal group B Rlp2086 has submitted the same report to the regulatory authorities.  No follow-up attempts are needed; information about lot/batch number cannot be obtained.