Protective immunity induced by an inhaled SARS-CoV-2 subunit vaccine.

Targeting the site of infection is a promising strategy for improving vaccine effectivity. To date, licensed COVID-19 vaccines have been administered intramuscularly despite the fact that SARS-CoV-2 is a respiratory virus. Here, we aim to induce local protective mucosal immune responses with an inhaled subunit vaccine candidate, ISR52, based on the SARS-CoV-2 Spike S1 protein. When tested in a lethal challenge hACE2 transgenic SARS-CoV-2 mouse model, intranasal and intratracheal administration of ISR52 provided superior protection against severe infection, compared to the subcutaneous injection of the vaccine. Interestingly for a protein-based vaccine, inhaled ISR52 elicited both CD4 and CD8 T-cell Spike-specific responses that were maintained for at least 6 months in wild-type mice. Induced IgG and IgA responses cross-reacting with several SARS- CoV-2 variants of concern were detected in the lung and in serum and protected animals displayed neutralizing antibodies. Based on our results, we are developing ISR52 as a dry powder formulation for inhalation, that does not require cold-chain distribution or the use of needle administration, for evaluation in a Phase I/II clinical trial.

Long-lasting T-cell response to SARS-CoV-2 antigens after vaccination-a prospective cohort study of HCWs working with COVID-19 patients.

BACKGROUND: Vaccination against SARS-CoV-2 reduces the risk of hospitalisation and death, but vaccine-induced IgG antibodies against the spike protein (IgG S) decline over time. Less is known about the nature of the vaccine-induced T-cell response to SARS-CoV-2 antigens. METHODS: IgG antibodies against nucleocapsid protein (IgG N), IgG S, and T-cell response towards SARS-CoV-2 antigens were determined in samples taken between November 2020 and November 2021 from a cohort of healthcare workers at an Infectious Diseases Department. RT-PCR screening for SARS-CoV-2 was encouraged once every four weeks in addition to testing when symptomatic or identified through contact tracing. Vaccination data were collected at the end of the study. RESULTS: At inclusion, T-cell response to SARS-CoV-2 antigens was found in 10/15 (66.7%) of participants with a previous/current COVID-19 infection and in 9/54 (16.7%) of participants with no prior/current history of COVID-19 infection. All participants with complete follow-up (n = 59) received two doses of a SARS-CoV-2 vaccine during the study. All participants demonstrated detectable IgG (S) antibodies at the end of the study, in median 278 days (IQR 112) after the second vaccine dose. All but four participants displayed T-cell responses towards SARS-CoV-2 antigens. IgG S antibody levels correlated with time since the second vaccine dose. In addition, previous COVID-19 infection and the strength of the S1 T-cell response correlated with IgG S antibody levels. However, no correlation was demonstrated between the strength of the T-cell response and time since the second vaccine dose. CONCLUSION: COVID-19 vaccination induces robust T-cell responses that remain for at least nine months.

Monitoring of the SARS-CoV-2 Omicron BA.1/BA.2 lineage transition in the Swedish population reveals increased viral RNA levels in BA.2 cases.

BACKGROUND: Throughout the SARS-CoV-2 pandemic, multiple waves of variants of concern have swept across populations, leading to a chain of new and yet more contagious variants dominating COVID-19 cases. Here, we tracked the remarkably rapid shift from Omicron BA.1 to BA.2 sublineage dominance in the Swedish population in early 2022 at a day-by-day basis. METHODS: Using a custom SARS-CoV-2 Omicron BA.1 lineage-typing RT-PCR assay, we analyzed 174,933 clinical upper airway samples collected during January to March 2022. FINDINGS: Our study demonstrates the feasibility and reliability of parallel lineage assignment of select variants at population scale, tracking the dominant sublineage transition from BA.1 to BA.2 at day-to-day resolution and uncovering nearly 2-fold higher levels of viral RNA in cases infected with Omicron BA.2 relative to BA.1. CONCLUSIONS: Our data provide unique insights into the Omicron BA.1 to BA.2 transition that occurred in Sweden during early 2022, and later, across the world. This may help to understand the increased transmissibility of the BA.2 variant.

A third dose SARS­CoV­2 BNT162b2 mRNA vaccine results in improved immune response in hemodialysis patients.

Background: The hemodialysis (HD) population has been a vulnerable group during the coronavirus disease 2019 (COVID-19) pandemic. Advanced chronic kidney disease with uremia is associated with weaker immune response to infections and an attenuated response to vaccines. The aim of this study was to study the humoral and cellular response to the second and third doses of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS­CoV­2) BNT162b2 mRNA vaccine in HD patients and to follow the response over time. Methods: The patients received their first two vaccine doses from 28 December 2020 within a 4-week interval and the third dose in September 2021 and were followed-up for humoral and cellular immune response at 1) 7-15 weeks and 2) 6-8 months after dose two (no t-cell reactivity measured), and 3) 3 weeks and 4) 3 months after dose three. Fifty patients were initially enrolled, and 40 patients were followed during the entire study. Levels of COVID-19 (SARS-CoV-2) IgG antibody against the Spike antigen (anti-S) and T-cell reactivity testing against the Spike protein using Enzyme-Linked ImmunoSpot (ELISPOT) technology were evaluated. Results: IgG antibodies to anti-S were detected in 35 (88%) of the 40 patients 7-15 weeks after vaccine dose two, 31 (78%) were positive, and 4 (10%) borderline. The median anti-S titer was 606 Abbott Units/milliliter (AU/mL) (interquartile range [IQR] 134-1,712). Three months after the third dose, anti-S was detected in 38 (95%) of 40 patients (P < 0.01 compared to after dose two), and the median anti-S titer was 9,910 AU/mL (IQR 2,325-26,975). Cellular reactivity was detected in 22 (55%), 34 (85%), and 28 (71%) of the 40 patients, and the median T-cell response was 9.5 (IQR 3.5-80), 51.5 (14.8-132), and 19.5 (8.8-54.2) units, respectively, for 6-8 months after dose two, 3 weeks, and 3 months after dose three. Conclusions: Our data show that a third dose of SARS­CoV­2 BNT162b2 mRNA vaccine gives a robust and improved immunological response in HD patients, but a few patients did not develop any anti-S response during the entire study, indicating the importance to monitor the vaccine response since those who do not respond could now be given monoclonal antibodies if they contract a COVID-19 infection or in the future antivirals.

Three Doses of SARS‑COV‑2 BNT162B2 MRNA Vaccine Results in an Enhanced Immunologic B- And T-Cell Response in Haemodialysis Patients

BACKGROUND AND AIMS The immune system is affected by uremia. Haemodialysis (HD) patients have an increased risk of acquiring infections due to many healthcare contacts and have a suboptimal response to vaccination and a high mortality from COVID-19 infection. Accumulating data indicate that two doses of vaccines are not enough, and most HD-patients have now received a third dose. The aim of the study was to describe the antibody and T-cell response to three doses of SARS‑CoV‑2 BNT162b2 mRNA vaccination and change over time. METHOD Initially, 50 patients (mean age 69.4 years and 62% men) with end-stage kidney disease (ESKD) and haemodialysis treatment, at the dialysis outpatient clinic, Uppsala Academic Hospital, Sweden were enrolled into the study. Administration of SARS‑CoV‑2 BNT162b2 mRNA vaccine began on 28 Decemeber 2020. In September 2021, the patients received their third vaccine dose. During the study four patients died, four received a kidney transplant and two did not receive the third vaccine dose. A total of 41 (82%) patients received three doses of vaccine and were followed up until 3 months after the third dose. The antibody response was measured at four timepoints;7–15 weeks and 6–8 months after the second dose, 3 weeks and 3 months after the third dose, and the T-cell response at three timepoints;7–15 weeks after the second dose, 3 weeks and 3 months after the third dose. SARS-CoV-2 IgG antibody test (Abbott Architect) was performed against Spike antigen (anti-S) positive both after COVID-19 infection and vaccination (quantitative method used in routine diagnostics at Laboratory of Clinical Microbiology, Uppsala) and T-cell reactivity testing against the Spike protein using ELISPOT technology measuring interferon-gamma activity was performed at ABC-labs, Solna. RESULTS After two doses, IgG antibodies (IgG abs) to anti-S were detected in 37 (74%) of 50 patients, 5 (10%) had a borderline response and 8 (16%) were negative. T-cell response were detected in 29 (58%) of 50 patients and in 21 (42%) no response was detected. Before the third dose IgG abs to anti-S were detected in 24 (52%) of 46 patients, 3 (7%) had a borderline response and 19 (41%) were negative. Three weeks after the third dose IgG abs to anti-S were detected in 39 (95%) of 41 patients, and 2 (5%) were negative. T-cell responses were detected in 35 (85%) of 41 patients and in 6 (15%) no response. Three months after the third dose IgG ab to anti-S were still detected in 38 (95%) of 40 patients, and 2 (5%) were negative. Changes in IgG ab to anti-S and T-cell response over time in patients who received all three doses of vaccine and were followed up until 3 months after the latest dose (n = 40 and 37) are displayed in Figures 1 and 2 (preliminary data). CONCLUSION These results highlight the need for at least three doses of the SARS‑CoV‑2 BNT162b2 mRNA vaccine. It also indicates that the effect of the vaccine decreases slower after dose 3 than after dose 2 since almost all patients had a measurable immune response 3 months after dose 3. However, not all patients develop an immunological response. In a clinical setting, it is justified to measure the antibody response after vaccination to identify patients that are not protected and where one needs to take other measures to protect them from infection and/or to give early treatment in case of symptoms.FIGURE 1: Changes in IgG antibodies to anti-S in patients who received three doses of SARS-CoV-2 BNT162b2 mRNA vaccine and were followed up until 3 months after the latest dose (n = 40).FIGURE 2: Changes T-cell response patients who received three doses of SARS-CoV-2 BNT162b2 mRNA vaccine and were followed up until 3 months after the latest dose (n = 37).

Humoral and cellular response to SARS-CoV-2 BNT162b2 mRNA vaccine in hemodialysis patients.

BACKGROUND: Hemodialysis (HD) patients have an increased risk of acquiring infections due to many health care contacts and may, in addition, have a suboptimal response to vaccination and a high mortality from Covid-19 infection. METHODS: In 50 HD patients (mean age 69.4 years, 62% men) administration of SARS-CoV-2BNT162b2 mRNA vaccine began in Dec 2020 and the immune response was evaluated 7-15 weeks after the last dose. Levels of Covid-19 (SARS-CoV-2) IgG antibody against the nucleocapsid antigen (anti-N) and the Spike antigen (anti-S) and T-cell reactivity testing against the Spike protein using ELISPOT technology were evaluated. RESULTS: Out of 50 patients, anti-S IgG antibodies indicating a vaccine effect or previous Covid-19 infection, were detected in 37 (74%), 5 (10%) had a borderline response and 8 (16%) were negative after two doses of vaccine. T-cell responses were detected in 29 (58%). Of the 37 patients with anti-S antibodies, 25 (68%) had a measurable T-cell response. 2 (40%) out of 5 patients with borderline anti-S and 2 (25%) without anti-S had a concomitant T-cell response. Twenty-seven (54%) had both an antibody and T-cell response. IgG antibodies to anti-N indicating a previous Covid-19 disease were detected in 7 (14%) patients. CONCLUSIONS: Most HD patients develop a B- and/or T-cell response after vaccination against Covid-19 but approx. 20% had a limited immunological response. T-cell reactivity against Covid-19 was only present in a few of the anti-S antibody negative patients.