Vaccinated individuals previously infected with SARS-CoV-2 show robust neutralization of the B.1.1.7 variant

New research published in the journal Viruses suggests recovering from a coronavirus disease 2019 (COVID-19) infection provides immunity against the B.1.1.7 (or UK) variant. The time when the previous infection took place and the variant involved in prior infection influenced cross-neutralization.

Findings also showed individuals with a prior infection benefitted from vaccinations. Neutralizing antibodies from natural infection were boosted, and vaccines helped against B.1.1.7.

The researchers write:

Uninfected vaccinees showed a small reduction in neutralization against the B.1.1.7 variant compared to both the WH1 strain and the D614G mutant. Interestingly, upon vaccination, previously infected individuals developed more robust neutralizing responses against B.1.1.7, suggesting that vaccines can boost the neutralization breadth conferred by natural infection.”

The study results suggest getting vaccinated is the best course of protection against variants of concerns such as B.1.1.7.

How they did it

Researchers used plasma samples collected from March 2020 to February 2021 from participants living in Catalonia, Spain. Thirty-two non-vaccinated individuals were collected about 48 or 196 days after presenting with symptoms. About 16 individuals infected in August 2020 donated plasma samples 44 days after symptom onset. Five patients were infected with the B.1.1.7 variant in January 2021.

There were also 32 participants who received two doses of the Pfizer/BioNTech vaccine who donated plasma samples 2 weeks after the second dose. The vaccinated group comprised of people never exposed to SARS-CoV-2 and previously infected individuals.

The researchers created a pseudovirus infection using an HIV reporter pseudovirus expressing either the original or B.1.1.7 SARS-CoV-2 spike protein. HEK293T cells expressed wild-type human ACE2 receptors.

Neutralization against the D614G mutation

When plasma samples were exposed to the pseudoviruses expressing different SARS-CoV-2 spike proteins, vaccinated individuals showed greater neutralizing power against the D614G mutation. Similar results were also observed in individuals who were not vaccinated but received antibodies from a prior infection.

B.1.1.7 weakened cross-neutralizing potency of vaccinated individuals compared to individuals who recovered from infection.

Neutralization against the B.1.1.7 variant

People infected in Spain’s first wave in March 2020 were exposed to the original D614 virus before being replaced by the G614 variant. In contrast, people infected during Spain’s second wave in August 2020 were exposed to the EU1 lineage, which made up all of summer 2020’s infections.

The neutralization response of participants infected during the first wave showed a small but significant decrease in neutralizing power against the B.1.1.7 variant compared to the D614G mutation. Six months later, cross-neutralization appeared to improve against both the D614G and the B.1.1.7 variant. Based on the results, the researchers suggest the neutralizing response from natural infection continued to evolve after the first onset of symptoms.

Individuals infected with the B.1.1.7 variant had high neutralization against the B.1.1.7 variant. These individuals were also able to cross-neutralize against the original SARS-CoV-2 strain and the D614G mutation.

Vaccinated individuals with prior infection had high neutralizing potency against B.1.1.7

For vaccinated individuals who were never infected with SARS-CoV-2, there was a decrease in B.1.1.7 cross-neutralization. But vaccinated individuals who had previously recovered from COVID-19 did not show a reduction in their neutralization response. In fact, neutralizing potency in these individuals appeared to increase against B.1.1.7.

Vaccinated-only individuals displayed more neutralizing titers than non-vaccinated individuals who were previously infected.

The results suggest that vaccination helped boost cross-neutralization responses from individuals who developed some antibodies after recovering from natural infection. In addition, the averages of neutralizing titers against each variant increased compared to vaccinated individuals who were not infected and nonvaccinated but previously infected groups.

In conclusion, the neutralizing response from infected individuals, while slowly decaying in magnitude, seems to show a good qualitative evolution which can be fully recalled upon vaccination. Importantly, our data suggest a better cross-neutralizing quality of antibodies induced by natural infection compared to those induced exclusively by vaccination.”

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