Waning of humoral immunity and COVID-19 vaccine: comment

Dear Editor,

We would like to share ideas on the publication ‘Waning of humoral immunity depending on the types of COVID-19 vaccine [1].’ Healthcare workers (HCWs) were enrolled by Lim et al. in a tertiary care hospital and given homologous two-dose vaccinations, followed with homologous or heterologous booster mRNA vaccinations [1]. Despite the relatively brief (3-month) follow-up after vaccinations and evaluation of the slopes from various antibody peak levels, Lim et al. found that two-dose homologous ChAdOx1 vaccination or homologous mRNA-1273 booster appears to induce more-durable antibody responses than two-dose homologous mRNA vaccination, homologous BNT162b2 booster, or two-dose ChAdOx1 followed by BNT62b2 booster [1].

In order to arrive at an accurate interpretation, a number of criteria must be taken into account. One of the potential complicating factors that might have had an impact on the outcomes of the initial dose was an extremely poor reaction. A correlation between asymptomatic COVID-19 and the absence of clinical symptoms may exist [2]. A COVID-19 must be ruled out if neither the previous symptoms nor the current clinical indicators are present. It is impossible to totally rule out the possibility of cross-contamination with an undiagnosed SARS-Co-V2 infection. Depending on inherited genetic variability, various people’s immune systems appear to react to COVID-19 vaccines differently [3]. Additional clinical study is required to assess whether or if the outcomes and clinical findings of the current work are supported.

Disclosure statement

No potential conflict of interest was reported by the author(s).