The quantity and quality of anti-SARS-CoV-2 antibodies show contrariwise association with COVID-19 severity: lessons learned from IgG avidity.

"Declarations Conflict of interestThe authors have no competing interests to declare that are relevant to the content of this article. Ethical approvalThis study was conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study protocol was approved by the Ethical Committee of Hamadan University of Medical Sciences. Consent to participationInformed consent forms were obtained from all participants. All methods were done in accordance with the relevant guidelines and regulations. Conflict of interest The authors have no competing interests to declare that are relevant to the content of this article."

"Funding This study has received financial support from Hamadan University of Medical Sciences (IR.UMSHA.REC.1400.422)."