PT - JOURNAL ARTICLE AU - Theerada Assawasaksakul AU - Seelwan Sathitratanacheewin AU - Preeyaporn Vichaiwattana AU - Nasamon Wanlapakorn AU - Yong Poovorawan AU - Yingyos Avihingsanon AU - Nawaporn Assawasaksakul AU - Wonngarm Kittanamongkolchai TI - Immunogenicity of the third and fourth BNT162b2 mRNA COVID-19 boosters and factors associated with immune response in patients with SLE and rheumatoid arthritis AID - 10.1136/lupus-2022-000726 DP - 2022 Jul 01 TA - Lupus Science & Medicine PG - e000726 VI - 9 IP - 1 4099 - http://lupus.bmj.com/content/9/1/e000726.short 4100 - http://lupus.bmj.com/content/9/1/e000726.full SO - Lupus Sci Med2022 Jul 01; 9 AB - Objectives To evaluate the safety and immunogenicity of third and fourth BNT162b2 boosters in patients with SLE and rheumatoid arthritis (RA).Methods Patients with SLE and RA aged 18–65 years who completed a series of inactivated, adenoviral vector, or heterogenous adenoviral vector/mRNA vaccines for at least 28 days were enrolled. Immunogenicity assessment was done before and day 15 after each booster vaccination. The third BNT162b2 booster was administered on day 1. Patients with suboptimal humoral response to the third booster dose (antireceptor-binding domain (RBD) IgG on day 15 <2360 BAU/mL) were given a fourth BNT162b2 booster on day 22.Results Seventy-one patients with SLE and 29 patients with RA were enrolled. The third booster raised anti-RBD IgG by 15-fold, and patients with positive neutralising activity against the Omicron variant increased from 0% to 42%. Patients with positive cellular immune response also increased from 55% to 94%. High immunosuppressive load and initial inactivated vaccine were associated with lower anti-RBD IgG titre. Fifty-four patients had suboptimal humoral responses to the third booster and 28 received a fourth booster dose. Although anti-RBD IgG increased further by sevenfold, no significant change in neutralising activity against the Omicron variant was observed. There were two severe SLE flares that occurred shortly after the fourth booster dose.Conclusions The third BNT162b2 booster significantly improved humoral and cellular immunogenicity in patients with SLE and RA. The benefit of a short-interval fourth booster in patients with suboptimal humoral response was unclear.Trial registration number TCTR20211220004.The data of this article are available upon reasonable request to the corresponding author.