Immune Response from COVID Recognizes Variants

April 7, 2021
Rachel Lutz

While it was a small study, its findings indicate protection against COVID-19 variants from the vaccine and from recovery from the infection.

Blood samples from patients who have recovered from the novel coronavirus (COVID-19) showed that T-cell response was able to recognize emerging variants and protect against them, according to a paper published in Open Forum Infectious Diseases.

Investigators from the National Institute of Allergy and Infectious Diseases (NIAID) aimed to determine whether CD8+ T-cell responses from COVID-19 patients maintain recognition for other variants of the infection. Previous research has suggested that virtually all anti-COVID-19 CD8+ T-cell responses should recognize these newly described variants, the study authors explained.

The study authors called it “inevitable” that new viral variants will emerge throughout this ongoing COVID-19 global pandemic. However, they said that most of the variants will disappear without notice because of incomplete or lack of genotypic surveillance, changes that do not impact viral fitness, and other conditions that would prevent their community spread. As new variants emerge, the study authors wrote, they should be monitored to identify possible accumulation of T-cell escape mutations.

The study authors also assume that both broad humoral and cell-mediated immunological responses are likely necessary for full protection against COVID-19. Additionally, they said the CD8+ T-cell response is important for prevention of further disease progression.

The investigators collected 30 blood cell samples from patients who recovered from COVID-19 prior to the emergence of these variants in late 2020. Then, they identified variants of the virus to test, including B.1.1.7 (originating in the United Kingdom), B.1.351 (originating in South Africa), and B.1.1.248 (originating in Brazil). The study authors also added that the mutations seen in the spike protein, which is used to attach and enter cells, could make the virus less recognizable to the T-cells and neutralizing antibodies.

About 60 percent of individuals included in the analysis were male, the study authors said, and they added that samples were collected a median of 42.5 days from initial diagnosis with COVID-19.

The investigators reported that the CD8+ T-cell responses remained mostly intact and was able to recognize the 3 variants that were tested. They noted that larger studies are needed but what remains from their findings is that the T-cell response for individuals who have had and recovered from COVID-19 as well as those who have been vaccinated against COVID-19 should be protected against the emerging variants, they wrote.

“Optimal immunity to SARS-Cov-2 likely requires strong multivalent T-cell responses in addition to neutralizing antibodies and other responses to protect against current SARS-CoV-2 strains and emerging variants, the authors indicate,” a press release from the National Institutes of Health said. “They stress the importance of monitoring the breadth, magnitude and durability of the anti-SARS-CoV-2 T-cell responses in recovered and vaccinated individuals as part of any assessment to determine if booster vaccinations are needed.”