Compared to prior infection, prior vaccination is associated with greater neutralization capacity against all COVID-19 variants

1. Vaccine boosters appear to be indicated for emergent SARS-CoV-2 variants in the future. 

2. Although both previously infected and not previously infected participants displayed neutralization capacity against all variants of COVID-19, those who had been previously infected displayed overall better neutralization capacity. 

Evidence Rating Level: 2 (Good) 

Study Rundown: Billions of vaccine doses have been administered worldwide as an effective means to reducing the healthcare and societal burden of SARS-CoV-2. Researchers in this study sought to further characterize the difference in immune responses triggered by vaccination compared to prior SARS-CoV-2 infection, and how this may result in differences in immunity against emerging mutant variants. Participants in the study were separated by previous infection status (with those that were previously infected having been infected between April and December 2020). The participants’ neutralization status to the panel of SARS-COV-2 isolates were determined. Previously infected vaccinated individuals were found to have higher PRNT50 titers against the SARS-CoV-2 isolates than non-previously infected vaccinated individuals. The majority of isolates had a higher NAb response in previously infected vaccinated participants than non-previously infected vaccinated individuals. The results found in this study strongly suggest the benefit of vaccine boosters for SARS-COV-2 for emerging variants. Strengths of this study include the accuracy of the data gathered. The participants in this study were followed longitudinally before and after vaccination. Limitations include the sample size of the study (40 participants) and the lack of diversity of the participants (primarily young Caucasian women). Study findings suggest that both prior infection and vaccination will result in neutralization capacity against COVID-19 variants. However, the benefits of vaccination as demonstrated by the superior neutralization capacity of individuals further proport the vital role of vaccination in the pandemic. 

Click to read the study in Nature Publishing Group

Relevant Reading: mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection

In-Depth [prospective cohort study]: Participants in the study were health care workers at Yale New Haven Hospital who were vaccinated between November 2020 and January 2021 and  volunteered for the study. Participants in the study were separated by previous infection status (with those that were previously infected having been infected between April and December 2020). Samples of Plasma and PBMCs were collected from participants at various intervals: prior to receiving the vaccine, 7- and 28- days after first vaccination dose, and 7-, 28- and 70 days after second vaccination dose. Data was analyzed using flow cytometry, neutralization, and ELISA assays. Previously infected vaccinated individuals were found to have higher PRNT50 titers against the SARS-COV-2 isolates than non-previously infected vaccinated individuals. The majority of isolates had a higher NAb response in previously infected vaccinated participants than non-previously infected vaccinated individuals.

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