>>>One important aspect of immunity not addressed by our work is cellular immunity contributed by cytotoxic lymphocytes, including T and NK cells. Even in the absence of neutralizing humoral immunity, previous studies have suggested that cellular immunity can mitigate severe or prolonged infection (Le Bert et al. 2020). In convalescent individuals, T-cell immunity would not be restricted to spike-derived epitopes, but also from other more abundant proteins such as nucleocapsid. As such, it would be reasonable to assume that T-cell-mediated immunity elicited by infection would remain largely intact for circulating variants including B.1.351. Indeed, although recent studies by Johnson & Johnson have demonstrated reduced overall efficacy in South Africa, there was substantially more protection against severe or fatal disease than for mild-to-moderate disease (Herper et al. 2021). However, with the exception of killed whole virus vaccines, all currently available vaccine designs only provide spike protein as the target immunogen, thus limiting T-cell immunity to spike epitopes. Notwithstanding, one recent study has demonstrated that mutations in spike epitopes do not impair T-cell responses despite escaping neutralizing antibodies (Skelly et al. 2021).
So... the jury is still out on if the vaccines generate a significant enough t-cell response to engender protection against a variant that may be able to elude the antibodies the vaccine confers, though it appears that the t-cell response is still durable from naturally infected individuals.