Intradermal Administration of a COVID-19 mRNA Vaccine in Elderly

Respiratory tract infections, e.g. caused by SARS-CoV-2, disproportionately affect elderly. Vaccination has shown to be the most cost-effective approach to prevent infections. However, older adults often fail to induce a potent immune response to vaccines, as was also seen recently for COVID-19 mRNA vaccines. This is likely due to immune dysfunction as a consequence of aging. To potentiate a stronger immune response, vaccine administration into the papillary dermis (intradermal, ID) has been proposed as an alternative strategy to intramuscular (IM) administration. Vaccination through the ID route has shown to be safe and equally or more effective than IM vaccination with a wide variety of vaccines. Recently, ID administration has been tested with two COVID-19 mRNA vaccines (Spikevax, Moderna and Comirnaty, Pfizer/BioNTech) in reduced (fractional) doses of the standard IM dose. To ease ID administration and thereby facilitate the implementation of this route, silicon-based microneedles have been developed. These needles have shown to allow ID administration of the Spikevax vaccine with equal safety and immunogenicity profiles as the traditional Mantoux approach in young adults. In the present study, we will investigate the immunogenicity of a 20 mcg dose of the COVID-19 mRNA Comirnaty vaccine through ID administration with silicon microneedles in elderly people (75 years and older), and compare this to immunogenicity of IM administration of a 20 mcg dose and a 30 mcg (standard IM) dose.