This is a summary, written by members of the CITF Secretariat, of:
Lapointe HR, Mwimanzi F, Cheung PK, Sang Y, Yaseen F, Kalikawe R, Datwani S, Waterworth R, Umviligihozo G, Ennis S, Young L, Dong W, Kirkby D, Burns L, Leung V, Holmes D, DeMarco DL, Simons J, Matic N, Montaner JSG, Brumme CJ, Prystajecky N, Niikura M, Lowe CF, Romney MG, Brockman MA, Brumme ZL. Serial infection with SARS-CoV-2 Omicron BA.1 and BA.2 following three-dose COVID-19 vaccination. medRxiv. 2022 May 21. doi: 10.1101/2022.05.19.22275026
The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.
A new case report, published in pre-print and therefore not yet peer-reviewed, indicates that Omicron reinfection – that is, two infections with distinct Omicron variants one after the other – is possible, even in vaccinated individuals. This result suggests that an Omicron infection may not induce long-lasting immunity, reinforcing the importance of continuing to practice preventive measures such as mask wearing, even for those who are vaccinated.
The paper prepared by Drs. Mark Brockman and Zabrina Brumme from Simon Fraser University and Dr. Marc Romney from the University of British Columbia. Being a case report, it is a detailed investigation of a noteworthy occurrence in a single individual.
- A healthy frontline healthcare worker, triply vaccinated with Pfizer-BioNTech’s Comirnaty mRNA vaccine, was diagnosed with an Omicron sub-lineage BA.1 infection in January 2022. Thirteen weeks later, the same individual experienced another Omicron infection, this time caused by the sub-lineage BA.2 variant. In both instances, the individual experienced moderate symptoms.
- One month after receiving their second and third vaccine doses, and prior to contracting COVID-19, the individual’s vaccine-induced antibody responses were completely typical. Specifically, the individual’s concentration of receptor-binding domain (RBD) antibodies and their ability to neutralize both the original and Omicron BA.1 strains were comparable to average levels seen in a comparison group of similarly vaccinated individuals who had never contracted COVID-19. These “average” responses however were not enough to protect against Omicron BA.1 infection.
- Following the BA.1 infection, the individual’s antibody responses to BA.1 and BA.2 were boosted compared to their vaccine-induced levels. These “boosted” responses however were not enough to protect against Omicron BA.2 infection
- Following the BA.2 infection, the individual’s antibody responses were not significantly boosted compared to their previously formed immunity.
In conclusion, these results indicate that symptomatic Omicron infections are possible in otherwise healthy triply vaccinated individuals, and that even Omicron-induced immunity may be unable to protect against subsequent Omicron reinfection. It also points to a need for future related studies with larger sample sizes.