Although some remarkable advances have been made within the detection, prevention of severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) and treatment of coronavirus disease (COVID-19), the emergence of the recent Omicron variant has highlighted how much there’s yet to learn regarding the immune responses of the virus.

The correlation between SARS-CoV-2 vaccine protectiveness and evaluation of adaptive immune response to SARS-CoV-2 infection continues to be unclear. Furthermore, vaccination has primarily focused on antibodies (Abs), and never much attention has been paid to T cells, which offer significant protection against severe diseases.

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T cells

As a result of limited studies on the role of T cells in SARS-CoV-2 research, policies regarding long-term protection from the virus after Abs decline and against emerging variants are difficult to find out. Although the quantitative measurement of Abs is more convenient, scientists are assessing T cells in vaccine trials and other research.

Inclusion of each Abs and T cells within the assessment of adaptive immune responses in the course of the starting of the pandemic could also help to counter misinformation that results in vaccine hesitancy in addition to provide swift messaging. This gap was quite outstanding within the initial results of the BNT162b2 vaccine trial in a population whose age ranges from 2 to five years which made it insufficient for it to receive emergency use authorization for this population.

Examination of T cell responses can even assist in the evaluation of protective immunity, clinical diagnosis, and vaccine assessment. As well as, evaluation of the broader adaptive immune responses may also help evaluate why some patients are asymptomatic while others are severely in poor health.

Now, a gaggle of outstanding scientists and physicians are urging the FDA to incorporate in its guidance to vaccine developers a suggestion for T-cell assessment in COVID-19 vaccine clinical trials to more comprehensively measure immune response. They write that it’s critical to measure T-cell responses along with antibodies to guage vaccine efficacy higher and make informed decisions regarding ongoing protection against current and future variants.

Improvement of data for the vulnerable population

Seven million immunocompromised people within the US struggle to guard themselves from infection. Information on T cell response may also help to tailor vaccination schedules or use prophylactic and other measures for these populations. To combat COVID-19, all tools have to be used, including T cell assessment, because of its disproportionate impact on some populations. Determination of the role of T cells in protective immunity will profit your complete population, especially those most vulnerable to infection.

Strengthening of public health response and confidence

Protection can have two dimensions, protecting people from getting infected and stopping severe illness from infection. Each the Omicron and Delta variants have sown evasion of antibody responses. Nevertheless, the emergence of the Omicron variant led to the evaluation of T cell importance to balance the lack of Ab-mediated protection. Several studies have reported the preservation of vaccine-induced T-cell response against this variant that results in continued vaccine efficacy.

Assessment of only the humoral aspect of the adaptive immune response cannot provide enough information on immunity. T cell responses have been reported to be more durable as in comparison with serum neutralizing Ab titers. Moreover, many studies have also suggested that Abs alone won’t be sufficient to guard against severe disease.

Subsequently, it could possibly be concluded that the continuation of the pandemic has emphasized T cell response for shielding against variants which are able to escaping neutralizing Ab response. Data on the broad immune response beyond Abs have to be collected, especially for the vulnerable populations, to find out public health strategies and policies. Further research on the complete range of adaptive responses is required to curb the present pandemic in addition to future pandemics and epidemics. Reducing misinformation regarding COVID-19 that results in vaccine hesitancy can also be vital for providing adequate protection from the disease.

Consistent with this attitude, 70 investigators signed a letter to the FDA on April 21, 2022, encouraging the inclusion of T cell responses along with antibody titers for the evaluation of SARS-CoV-2 vaccines in humans.