The adverse reactions of the TLR9 agonist CpG-OND mainly manifest as lymphocytopenia, mild fever, seizures, and transient neurological deterioration.558 The TLR9 agonist, MGN1703, in addition to common adverse reactions, can also cause cough, erythema, dyspnea, neutropenia, nausea, asthenia, back pain, anemia, decreased appetite, and prolonged activated partial thromboplastin time. Here, TLR9 is linked to lymphopenia.