very sick with Covid for months/I have Long COVID; The patient received Moderna Covid-19 vaccine and Pfizer vaccine; The patient received Moderna Covid-19 vaccine and Pfizer vaccine; I had a very harsh and long lasting reaction to the moderna vaccine in 2021/had a  terrible reaction to moderna vaccine; This spontaneous case was reported by a consumer and describes the occurrence of IMMUNISATION REACTION (I had a very harsh and long lasting reaction to the moderna vaccine in 2021/had a  terrible reaction to moderna vaccine) and POST-ACUTE COVID-19 SYNDROME (very sick with Covid for months/I have Long COVID) in a patient of an unknown age and gender who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for an unknown indication.    No Medical History information was reported.   In 2021, the patient received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In November 2021, the patient received dose of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) (unknown route) 1 dosage form. In 2021, the patient experienced IMMUNISATION REACTION (I had a very harsh and long lasting reaction to the moderna vaccine in 2021/had a  terrible reaction to moderna vaccine) (seriousness criterion medically significant). On an unknown date, the patient experienced POST-ACUTE COVID-19 SYNDROME (very sick with Covid for months/I have Long COVID) (seriousness criterion medically significant), COVID-19 IMMUNISATION (The patient received Moderna Covid-19 vaccine and Pfizer vaccine) and INTERCHANGE OF VACCINE PRODUCTS (The patient received Moderna Covid-19 vaccine and Pfizer vaccine). At the time of the report, IMMUNISATION REACTION (I had a very harsh and long lasting reaction to the moderna vaccine in 2021/had a  terrible reaction to moderna vaccine), POST-ACUTE COVID-19 SYNDROME (very sick with Covid for months/I have Long COVID), COVID-19 IMMUNISATION (The patient received Moderna Covid-19 vaccine and Pfizer vaccine) and INTERCHANGE OF VACCINE PRODUCTS (The patient received Moderna Covid-19 vaccine and Pfizer vaccine) outcome was unknown.        The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.       Concomitant medications were not reported.  It was reported that patient had a terrible reaction to moderna vaccine in 2021. Patient was also very sick with Covid for months and had to go to the ER. Patient stated that when got the Pfizer booster in the fall 2021, was only sick for a week that was manageable. Treatment information was not reported. Company comment- This spontaneous case concerns a patient of unknown age and gender with no medical history reported, who experienced the unexpected, serious (medically significant) events post-acute COVID-19 syndrome and immunization reaction after receiving a dose of mRNA-1273 vaccine. Temporal association cannot be assessed due to lack of information on onset date of the events and vaccination date.  A dose of TOZINAMERAN vaccine, given as a booster dose, was also administered (revaccination with different COVID-19 vaccine and interchange of vaccine products). It was reported patient had a very harsh and long-lasting reaction to the Moderna vaccine. She also had long COVID, she was very sick with COVID for months and had to go to the ER. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.