Safety and antibody response of recipients who unexpectedly received undiluted prime dose of BNT162b2 COVID-19 vaccine in Taiwan

We reported 25 recipients (14 females and 11 males) aged from 18 to 65 years who unexpect-edly received a primary dose of undiluted BNT162b2 vaccine (180 mg). The most common adverse reactions included injection site pain (n = 22), followed by fever (9), fatigue (8), chest tightness (6), and dizziness (6). The most common laboratory abnormalities were anemia (n = 4) and elevated liver transaminase level (4), followed by abnormal leukocyte counts (3) and elevated D-dimer level (3). The adverse reactions and laboratory abnormalities of these recipients were mild and spontaneously recovered within a few weeks. Significant elevations of anti-SARS-CoV-2 spike IgG titers after a booster dose of the BNT162b2 were found. Similar to reports of BNT162b2 clinical trials, the adverse reactions and laboratory abnormalities of these recipients were mild, and they spontaneously recovered within a few weeks. These re-sults provide clinical and immunological effects of undiluted BNT162b2 vaccine inoculation. Copyright (c) 2022, Formosan Medical Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

We reported the clinical and immunological effects of undiluted BNT162b2 vaccine inoculation in 25 recipients. The most common adverse reactions were injection site pain, fever, fatigue, chest tightness, and dizziness. Laboratory abnormalities included anemia and elevated liver transaminase level. These adverse reactions and abnormalities were mild and spontaneously recovered within a few weeks. The spike IgG titers significantly increased after a booster dose of BNT162b2.