Stiffness; Locking of the joint; My thumb kept getting worse and lead to tendinitis; Constant waking up in the night due to the pain; Joint pain, tendinitis in left hand; Started like freezing like with tendinitis, tendinitis in left hand; Second knuckle on the left hand became inflamed, not the big knuckle but the joint right after, Joint pain; A lot of pain; At first all five fingers were inflammed, inflamation in fingers of left hand after second shot; This spontaneous case was reported by a physician and describes the occurrence of ARTHRITIS (Second knuckle on the left hand became inflamed, not the big knuckle but the joint right after, Joint pain), TENDONITIS (Started like freezing like with tendinitis, tendinitis in left hand), MUSCULOSKELETAL STIFFNESS (Stiffness), PAIN (A lot of pain) and INFLAMMATION (At first all five fingers were inflammed, inflamation in fingers of left hand after second shot) in a 51-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 026B21A and 027A21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On 06-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 03-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 04-Apr-2021, the patient experienced ARTHRITIS (Second knuckle on the left hand became inflamed, not the big knuckle but the joint right after, Joint pain), PAIN (A lot of pain) and INFLAMMATION (At first all five fingers were inflammed, inflamation in fingers of left hand after second shot). On 05-Apr-2021, the patient experienced TENDONITIS (Started like freezing like with tendinitis, tendinitis in left hand) and ARTHRALGIA (Joint pain, tendinitis in left hand). On an unknown date, the patient experienced MUSCULOSKELETAL STIFFNESS (Stiffness), JOINT LOCK (Locking of the joint), CONDITION AGGRAVATED (My thumb kept getting worse and lead to tendinitis) and INSOMNIA (Constant waking up in the night due to the pain). The patient was treated with CORTISONE at a dose of Shot a month ago. At the time of the report, ARTHRITIS (Second knuckle on the left hand became inflamed, not the big knuckle but the joint right after, Joint pain), TENDONITIS (Started like freezing like with tendinitis, tendinitis in left hand), MUSCULOSKELETAL STIFFNESS (Stiffness), PAIN (A lot of pain), INFLAMMATION (At first all five fingers were inflammed, inflamation in fingers of left hand after second shot), JOINT LOCK (Locking of the joint), CONDITION AGGRAVATED (My thumb kept getting worse and lead to tendinitis), INSOMNIA (Constant waking up in the night due to the pain) and ARTHRALGIA (Joint pain, tendinitis in left hand) had not resolved.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter considered ARTHRITIS (Second knuckle on the left hand became inflamed, not the big knuckle but the joint right after, Joint pain) to be possibly related. No further causality assessments were provided for TENDONITIS (Started like freezing like with tendinitis, tendinitis in left hand), MUSCULOSKELETAL STIFFNESS (Stiffness), PAIN (A lot of pain), INFLAMMATION (At first all five fingers were inflammed, inflamation in fingers of left hand after second shot), JOINT LOCK (Locking of the joint), CONDITION AGGRAVATED (My thumb kept getting worse and lead to tendinitis), INSOMNIA (Constant waking up in the night due to the pain) and ARTHRALGIA (Joint pain, tendinitis in left hand).    The patient stated that he experienced joint pain, stiffness and inflamation in fingers of left hand post second shot. Patient has never diagnosed with COVID-19.  The patient stated that, after a month post second dose, his little finger through his index finger became better, but his thumb kept getting worse and lead to tendinitis and locking of the joint. He also stated that it caused him a lot of pain, minimal use of his left hand as he is a left-hander and constant wake up in the night due to the pain and popping of his thumb joint. The hand specialist saaid that it is usually caused by inflamation and in this case, probably from the vaccine.     The patient stated that he received a very painful cortisone injection in his thumb joint. He also stated that his physician told him it might lead to surgery if tendons do not release.   No concomitant medications were reported   Most recent FOLLOW-UP information incorporated above includes: On 10-Aug-2021: New adverse events- Musculoskeletal stiffness, arthralgia, joint lock, condition aggravated, insomnia and outcomes included. Start dates for events updated. Patient information, Vaccine information, dose start dates and Vaccine Facility Information updated. Causality for event Arthritis was updated.