Peptide pool stimulation enables longitudinal analysis of SARS-CoV-2–specific CD4 ⁺ and CD8 ⁺ T cells in ICU-admitted COVID-19 patients.

Infection- or vaccination-induced SARS-CoV-2 S–specific CD4 ⁺ T cells are indifferent to the S mutations of variants of concern.

The severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) Omicron variant is spreading rapidly, even in vaccinated individuals, raising concerns about immune escape. Here, we studied neutralizing antibodies and T cell responses targeting SARS-CoV-2 D614G [wild type (WT)] and the Beta, Delta, and Omicron variants of concern in a cohort of 60 health care workers after immunization with ChAdOx-1 S, Ad26.COV2.S, mRNA-1273, or BNT162b2. High binding antibody levels against WT SARS-CoV-2 spike (S) were detected 28 days after vaccination with both mRNA vaccines (mRNA-1273 or BNT162b2), which substantially decreased after 6 months. In contrast, antibody levels were lower after Ad26.COV2.S vaccination but did not wane. Neutralization assays showed consistent cross-neutralization of the Beta and Delta variants, but neutralization of Omicron was significantly lower or absent. BNT162b2 booster vaccination after either two mRNA-1273 immunizations or Ad26.COV2 priming partially restored neutralization of the Omicron variant, but responses were still up to 17-fold decreased compared with WT. SARS-CoV-2–specific T cells were detected up to 6 months after all vaccination regimens, with more consistent detection of specific CD4 ⁺ than CD8 ⁺ T cells. No significant differences were detected between WT- and variant-specific CD4 ⁺ or CD8 ⁺ T cell responses, including Omicron, indicating minimal escape at the T cell level. This study shows that vaccinated individuals retain T cell immunity to the SARS-CoV-2 Omicron variant, potentially balancing the lack of neutralizing antibodies in preventing or limiting severe COVID-19. Booster vaccinations are needed to further restore Omicron cross-neutralization by antibodies.

In July 2022, the ongoing monkeypox (MPX) outbreak was declared a public health emergency of international concern. Modified vaccinia Ankara—Bavarian Nordic (MVA-BN, also known as Imvamune, JYNNEOS or Imvanex) is a third-generation smallpox vaccine that is authorized and in use as a vaccine against MPX. To date, there are no data showing MPX virus (MPXV)-neutralizing antibodies in vaccinated individuals nor vaccine efficacy against MPX. Here we show that MPXV-neutralizing antibodies can be detected after MPXV infection and after historic smallpox vaccination. However, a two-shot MVA-BN immunization series in non-primed individuals yields relatively low levels of MPXV-neutralizing antibodies. Dose-sparing of an MVA-based influenza vaccine leads to lower MPXV-neutralizing antibody levels, whereas a third vaccination with the same MVA-based vaccine significantly boosts the antibody response. As the role of MPXV-neutralizing antibodies as a correlate of protection against disease and transmissibility is currently unclear, we conclude that cohort studies following vaccinated individuals are necessary to assess vaccine efficacy in at-risk populations.

Halting transmission: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) glycoprotein binds to host cells and initiates membrane fusion and cell infection. This stage in the virus life history is currently a target for drug inhibition. De Vries et al. designed highly stable lipoprotein fusion inhibitors complementary to a conserved repeat in the C terminus of S that integrate into host cell membranes and inhibit conformational changes in S necessary for membrane fusion. The authors tested the performance of the lipoproteins as a preexposure prophylactic in a ferret-to-ferret transmission study. Intranasal administration of the peptide 2 days before cohousing with an infected ferret for 24 hours completely protected animals in contact from infection and showed efficacy against mutant viruses. Because ferrets do not get sick from SARS-CoV-2, disease prevention could not be tested in this model. Science , this issue p. 1379

Influenza vaccination can be less effective in patients treated with immunosuppressive therapy. However, little is known about the effects of ustekinumab; an anti-IL-12/23 agent used to treat Crohn’s disease (CD), on vaccination response. In this prospective study, we assessed immune responses to seasonal influenza vaccination in CD patients treated with ustekinumab compared to CD patients treated with anti-TNFα therapy (adalimumab) and healthy controls. Humoral responses were assessed with hemagglutinin inhibition (HI) assays. Influenza-specific total CD3⁺, CD3⁺CD4⁺, and CD3⁺CD8⁺ T-cell responses were measured with flow cytometry. Fifteen patients treated with ustekinumab; 12 with adalimumab and 20 healthy controls were vaccinated for seasonal influenza in September 2018. Seroprotection rates against all vaccine strains in the ustekinumab group were high and comparable to healthy controls. Seroconversion rates were comparable, and for A/H3N2 highest in the ustekinumab group. HI titers were significantly higher in the ustekinumab group and healthy controls than in the adalimumab group for the B/Victoria strain. Post-vaccination T-cell responses in the ustekinumab group were similar to healthy controls. One-month post-vaccination proliferation of CD3⁺CD8⁺ T-cells was highest in the ustekinumab group. In conclusion, ustekinumab does not impair immune responses to inactivated influenza vaccination. Therefore, CD patients treated with ustekinumab can be effectively vaccinated for seasonal influenza.