Intradermal ChAdOx1 Vaccine Following Two CoronaVac Shots: A Case Report

Abstract

Inactivated SARS-CoV-2 vaccines are used in many countries with uncertain immunogenicity. Intradermal ChAdOx1 has been proposed as a resource-efficient heterologous third booster shot. A 52-year-old healthy male healthcare professional had received two intramuscular CoronaVac shots on 21 April and 23 May 2021, and volunteered to take a 0.1 mL ChAdOx1 vaccine intradermally on 29 June 2021, with minimal local reactions. The declining IgG levels against spike protein from the two CoronaVac shots increased to higher than 10,000 AU/mL two weeks after the intradermal ChAdOx1. Moreover, the neutralizing antibody increased from 66.77% to almost 100%. A ratio of 6.6:9.7 of IgA:IgG was observed. The 50% pseudovirus neutralization titer (PVNT50) against lentiviral pseudovirus bearing a codon-optimized spike gene (wild type, alpha, beta, and delta) were 1812.42, 822.99, 1025.42, 1347.13, respectively. The SARS-CoV-2-specific T cells to spike protein–peptide pools (532–788 SFU/106 PBMCs) were detected. In conclusion, the antibody and cellular responses to the intradermal ChAdOx1, as a third booster dose in a healthy volunteer who received two intramuscular CoronaVac shots, revealed a dramatic increase in the total antibodies, including IgG, IgA, as well as T cell responses against spike protein. The immune response from intradermal ChAdOx1 should be further investigated in a larger population.

Immunogenicity and safety of an intradermal fractional third dose of ChAdOx1 nCoV-19/AZD1222 vaccine compared with those of a standard intramuscular third dose in volunteers who previously received two doses of CoronaVac: A randomized controlled trial

“…However, participants randomized to the IM administration control arm in this study did not receive a standard dose [35] . A case report by Singhatiraj et al also showed excellent immunogenicity of an ID 20% fractional dose of AZD1222 among participants who had previously received two doses of CoronaVac [36] .…”

Immunoglobulin A response to SARS-CoV-2 infection and immunity

“…Interestingly, the optimized production of neutralizing secretory IgA antibodies, especially in naïve vaccine recipients, is obtained after a second-dose-induced boost, confirming the importance of the two-to-three doses SARS-CoV-2 vaccination program [ [128] , [129] , [130] ]. In addition, it is remarked that most studies reported that IgA antiviral immunity is mainly induced by mRNA-based vaccines than other vaccines, including attenuated vaccines [ 24 , 128 , [130] , [131] , [132] ], these mRNA vaccines added protective-value lies in their ability to induce neutralizing IgA.…”

Immunogenicity and reactogenicity of accelerated regimens of fractional intradermal COVID-19 vaccinations

“…Fractional doses 10-20% of their IM or SC dosages are generally used for ID administration ( 5 – 8 ). Such dose reductions could help increase vaccine supply and availability as well as reduce vaccination costs by 60-80% compared to IM regimens ( 3 , 8 , 9 ). Addressing these factors are crucial to navigating global vaccine shortages, particularly in low- and middle-income countries ( 3 ).…”