A single dose of vaccine is enough to give robust immune response in people with prior infection
We present five studies published till now, which show that a single dose of vaccine may be enough to elicit a robust immune response in people previously infected with SARS-CoV-2.
Individuals with pre-existing immunity showed an antibody response to the first vaccine dose that was either equal to or greater than the titers found in uninfected individuals after the second dose. The study also found that reactogenicity was significantly higher in previously infected individuals.
Policy changes to give previously infected individuals a single dose of vaccine would not negatively influence their antibody titers. Also, it will spare them unnecessary pain and make many urgently needed vaccine doses available to the needy.
Ref: Robust spike antibody responses and increased reactogenicity in seropositive individuals after a single dose of SARS-CoV-2 mRNA vaccine. Florian Krammer, Komal Srivastava, the PARIS team, Viviana Simon. medRxiv 2021.01.29.21250653;
Healthcare workers (HCW) previously infected by COVID-19 showed clear secondary antibody responses to vaccination. Their IgG spike binding titers increased rapidly by seven days and peaked by 10- 14 days post-vaccination. Compared to HCW without a prior COVID-19 infection, the previously infected ones showed statistically significant higher antibody titers of binding and functional antibody (p<.0001 for each of the time points tested).
Currently, the world is facing a vaccine shortage. Also, the correlates of protection have yet to be identified. In such times, the following two recommendations from this study seem evidence-based and practical.
1) A single dose of vaccine for individuals who had a lab-confirmed COVID-19 diagnosis.
2) Individuals with a previous infection and lab-confirmed COVID-19 diagnosis can be placed at a lower priority for vaccinations.
Ref: Single Dose Vaccination in Healthcare Workers Previously Infected with SARS-CoV-2. Saman Saadat, Zahra Rikhtegaran Tehrani, James Logue, Michelle Newman, Matthew B. Frieman, Anthony D. Harris, Mohammad M. Sajadi. medRxiv 2021.01.30.21250843; doi: https://doi.org/10.1101/2021.01.30.21250843
Individuals who were previously infected will benefit from even a single immunization with mRNA vaccines. Boosting the pre-existing antibody responses to the spike protein will significantly increase serum neutralizing antibody responses against vaccine-matched and emerging variants.
Ref: Antibodies elicited by SARS-CoV-2 infection and boosted by vaccination neutralize an emerging variant and SARS-CoV-1
Leonidas Stamatatos, Julie Czartoski, Yu-Hsin Wan, Leah J. Homad, Vanessa Rubin, Hayley Glantz, Moni Neradilek, Emilie Seydoux, Maedeline F. Jennewein, Anna J. MacCamy, Junli Feng, Gregory Mize, Stephen C. De Rosa, Andrés Finzi, Maria Lemos, Kristen W. Cohen, Zoe Moodie, M. Juliana McElrath, Andrew T. McGuire
medRxiv 2021.02.05.21251182; doi: https://doi.org/10.1101/2021.02.05.21251182
The study showed robust increases in humoral and antigen-specific antibody-secreting cell (ASC) responses following each vaccine dose in previously uninfected individuals. In contrast, those previously exposed to SARS-CoV-2 exhibited an interesting phenomenon. They showed strong humoral and antigen-specific ASC responses to the first dose but muted responses to the second vaccine dose at the study time-points.
The study, in short, showed that previously infected individuals elicited poor immune responses to the booster dose of an mRNA vaccine.
Ref: Poor antigen-specific responses to the second BNT162b2 mRNA vaccine dose in SARS-CoV-2-experienced individuals
Marie I. Samanovic, Amber R. Cornelius, Jimmy P. Wilson, Trishala Karmacharya, Sophie L. Gray-Gaillard, Joseph Richard Allen, Sara Wesley Hyman, Gali Moritz, Mahnoor Ali, Sergei B. Koralov, Mark J. Mulligan, Ramin Sedaghat Herati
medRxiv 2021.02.07.21251311; doi: https://doi.org/10.1101/2021.02.07.21251311
A phase IV study in a sample of 425 healthcare providers in Greece presented real-world evidence on the first dose of an mRNA vaccine's immunogenicity. The first dose of the mRNA vaccine elicited a potent humoral immune response in the uninfected group, and the response was even more significant in previously infected individuals.
Ref: Kontopoulou, Konstantina and Ainatzoglou, Alexandra and Ifantidou, Athina and Nakas, Christos and Goudi, Georgia and Antoniadou, Eleni and Adamopoulos, Vasilios and Papadopoulos, Nikitas and Papazisis, Georgios.
Immunogenicity after the First Dose of the BNT162b2 mRNA COVID-19 Vaccine: Real-World Evidence from Greek Healthcare Workers (February 3, 2021). Available at SSRN: https://ssrn.com/abstract=3786138 or http://dx.doi.org/10.2139/ssrn.3786138