GNB3 c.825c>T polymorphism influences T-cell but not antibody response following vaccination with the mRNA-1273 vaccine

The emergence of SARS-coronavirus 2 (SARS-CoV-2) marks the third highly pathogenic coronavirus to spill over into the human population. SARS-CoV-2 is highly transmissible with a broad tissue tropism that is likely perpetuating the pandemic. However, important questions remain regarding its transmissibility and pathogenesis. In this review, we summarize current SARS-CoV-2 research, with an emphasis on transmission, tissue tropism, viral pathogenesis, and immune antagonism. We further present advances in animal models that are important for understanding the pathogenesis of SARS-CoV-2, vaccine development, and therapeutic testing. When necessary, comparisons are made from studies with SARS to provide further perspectives on COVID-19, as well as draw inferences for future investigations.

To The Editor: We recently reported the results of a phase 1 trial of a messenger RNA vaccine, mRNA-1273, to prevent infection with SARS-CoV-2; those interim results covered a period of 57 days after the first vaccination. 1,2 Here, we describe immunogenicity data 119 days after the first vaccination (90 days after the second vaccination) in 34 healthy adult participants in the same trial who received two injections of vaccine at a dose of 100 μg. The injections were received 28 days apart. The recipients were stratified according to age (18 to 55 years, 56 to 70 years, or ≥71 years), and the assays used have been described previously. 1,2 At the 100-μg dose, mRNA-1273 produced high levels of binding and neutralizing antibodies that declined slightly over time, as expected, but they remained elevated in all participants 3 months after the booster vaccination. Binding antibody responses to the spike receptor–binding domain were assessed by enzyme-linked immunosorbent assay. At the day 119 time point, the geometric mean titer (GMT) was 235,228 (95% confidence interval [CI], 177,236 to 312,195) in participants 18 to 55 years of age, 151,761 (95% CI, 88,571 to 260,033) in those 56 to 70 years of age, and 157,946 (95% CI, 94,345 to 264,420) in those 71 years of age or older (Figure 1). Serum neutralizing antibodies continued to be detected in all the participants at day 119. On a pseudovirus neutralization assay, the 50% inhibitory dilution (ID50) GMT was 182 (95% CI, 112 to 296) in participants who were between the ages of 18 and 55 years, 167 (95% CI, 88 to 318) in those between the ages of 56 and 70 years, and 109 (95% CI, 68 to 175) in those 71 years of age or older. On the live-virus focus reduction neutralization test mNeonGreen assay, the ID50 GMT was 775 (95% CI, 560 to 1071), 685 (95% CI, 436 to 1077), and 552 (95% CI, 321 to 947) in the same three groups, respectively. On the live-virus plaque-reduction neutralization testing assay, the 80% inhibitory dilution GMT was similarly elevated at 430 (95% CI, 277 to 667), 269 (95% CI, 134 to 542), and 165 (95% CI, 82 to 332) in the same three groups, respectively (Figure 1). At day 119, the binding and neutralizing GMTs exceeded the median GMTs in a panel of 41 controls who were convalescing from Covid-19, with a median of 34 days since diagnosis (range, 23 to 54). 2 No serious adverse events were noted in the trial, no prespecified trial-halting rules were met, and no new adverse events that were considered by the investigators to be related to the vaccine occurred after day 57. Although correlates of protection against SARS-CoV-2 infection in humans are not yet established, these results show that despite a slight expected decline in titers of binding and neutralizing antibodies, mRNA-1273 has the potential to provide durable humoral immunity. Natural infection produces variable antibody longevity 3,4 and may induce robust memory B-cell responses despite low plasma neutralizing activity. 4,5 Although the memory cellular response to mRNA-1273 is not yet defined, this vaccine elicited primary CD4 type 1 helper T responses 43 days after the first vaccination, 2 and studies of vaccine-induced B cells are ongoing. Longitudinal vaccine responses are critically important, and a follow-up analysis to assess safety and immunogenicity in the participants for a period of 13 months is ongoing. Our findings provide support for the use of a 100-μg dose of mRNA-1273 in an ongoing phase 3 trial, which has recently shown a 94.5% efficacy rate in an interim analysis.

To the Editor: Interim results from a phase 3 trial of the Moderna mRNA-1273 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine indicated 94% efficacy in preventing coronavirus disease 2019 (Covid-19). 1 The durability of protection is currently unknown. We describe mRNA1273-elicited binding and neutralizing antibodies in 33 healthy adult participants in an ongoing phase 1 trial, 2-4 stratified according to age, at 180 days after the second dose of 100 μg (day 209). Antibody activity remained high in all age groups at day 209. Binding antibodies, measured by means of an enzyme-linked immunosorbent assay against SARS-CoV-2 spike receptor–binding domain, 2 had geometric mean end-point titers (GMTs) of 92,451 (95% confidence interval [CI], 57,148 to 149,562) in participants 18 to 55 years of age, 62,424 (95% CI, 36,765 to 105,990) in those 56 to 70 years of age, and 49,373 (95% CI, 25,171 to 96,849) in those 71 years of age or older. Nearly all participants had detectable activity in a pseudovirus neutralization assay, 2 with 50% inhibitory dilution (ID50) GMTs of 80 (95% CI, 40 to 135), 57 (95% CI, 30 to 106), and 59 (95% CI, 29 to 121), respectively. On the more sensitive live-virus focus-reduction neutralization mNeonGreen test, 4 all the participants had detectable activity, with ID50 GMTs of 361 (95% CI, 258 to 504), 171 (95% CI, 95 to 307), and 131 (95% CI, 69 to 251), respectively; these GMTs were lower in participants 56 to 70 years of age (P=0.03) and in those 71 years of age or older (P=0.005) than in those 18 to 55 years of age (Figure 1; also see the Supplementary Appendix, available with the full text of this letter at NEJM.org). The estimated half-life of binding antibodies after day 43 for all the participants was 52 days (95% CI, 46 to 58) calculated with the use of an exponential decay model, which assumes a steady decay rate over time, and 109 days (95% CI, 92 to 136) calculated with the use of a power-law model (at day 119), which assumes that decay rates decrease over time. The neutralizing antibody half-life estimates in the two models were 69 days (95% CI, 61 to 76) and 173 days (95% CI, 144 to 225) for pseudovirus neutralization and 66 days (95% CI, 59 to 72) and 182 days (95% CI, 153 to 254) for live-virus neutralization. As measured by ΔAICc (change in Akaike information criterion, corrected for small sample size), the best fit for binding and neutralization were the power-law and exponential decay models, respectively (see the Supplementary Appendix). These results are consistent with published observations of convalescent patients with Covid-19 through 8 months after symptom onset. 5 Although the antibody titers and assays that best correlate with vaccine efficacy are not currently known, antibodies that were elicited by mRNA-1273 persisted through 6 months after the second dose, as detected by three distinct serologic assays. Ongoing studies are monitoring immune responses beyond 6 months as well as determining the effect of a booster dose to extend the duration and breadth of activity against emerging viral variants. Our data show antibody persistence and thus support the use of this vaccine in addressing the Covid-19 pandemic.