Current vaccine strategies against SARS-CoV-2: Promises and challenges

COVID-19 vaccine uptake among young adults: Influence of asthma and sociodemographic factors

Background

Asthma was initially described as a risk factor for severe coronavirus disease 2019 (COVID-19), but the uptake of COVID-19 vaccine among young adults with asthma is not well studied.

Objective

The aims were to assess COVID-19 vaccine uptake among young adults in general and to explore potential determinants including sociodemographic factors and asthma.

Methods

Participants from the population-based birth cohort BAMSE (Barn/Child, Allergy, Milieu, Stockholm, Epidemiology) were included: 4,064 in the study population, 3,064 in a follow-up at age 24 years, and 2,049 in a COVID-19 follow-up (mean age, 26.5 years). Asthma and asthma-associated characteristics were assessed through questionnaires and clinical data. Data on all COVID-19 vaccines registered between January 1, 2021, and February 15, 2023, were extracted from the National Vaccination Register.

Results

In the study population (n = 4,064), 53.9% had ≥3 COVID-19 vaccine doses registered. In the 24-year follow-up population (n = 3,064), vaccine uptake differed in relation to education (P < .001). Among the participants with university/college education, 65.7% had an uptake of ≥3 doses of vaccine, compared to 54.1% among the participants with elementary school/high school education. Participants with asthma had decreased odds of receiving ≥3 doses (adjusted odds ratio = 0.62; 95% confidence interval, 0.41-0.92) and ≥2 compared to peers without asthma. Those with uncontrolled disease also had decreased odds of receiving ≥3 doses (adjusted odds ratio = 0.30; 95% confidence interval, 0.13-0.66) and ≥2 compared to participants with controlled asthma.

Conclusions

COVID-19 vaccine uptake among young adults is lower in individuals from households with lower socioeconomic status and among those with asthma, including uncontrolled asthma.

Strong humoral response after Covid-19 vaccination correlates with the common HLA allele A*03:01 and protection from breakthrough infection

Few data exist on the role of genetic factors involving the HLA system on response to Covid-19 vaccines. Moving from suggestions of a previous study investigating the association of some HLA alleles with humoral response to BNT162b2, we here compared the HLA allele frequencies among weak (n = 111) and strong (n = 123) responders, defined as those healthcare workers with the lowest and the highest anti-Spike antibody levels after vaccination. Individuals with clinical history of Covid-19 or positive anti-nucleocapside antibodies were excluded. We found the common HLA-A*03:01 allele as an independent predictor of strong humoral response (OR = 12.46, 95% CI: 4.41-35.21, p < 0.0001), together with younger age of vaccines (p = 0.004). Correlation between antibody levels and protection from breakthrough infection has been observed, with a 2-year cumulative incidence of 42% and 63% among strong and weak responders, respectively (p = 0.03). Due to the high frequency of HLA-A*03:01 and the need for seasonal vaccinations against SARS-CoV-2 mutants, our findings provide useful information about the inter-individual differences observed in humoral response after Covid-19 vaccine and might support further studies on the next seasonal vaccines.

Structural basis for translation inhibition by MERS-CoV Nsp1 reveals a conserved mechanism for betacoronaviruses

All betacoronaviruses (β-CoVs) encode non-structural protein 1 (Nsp1), an essential pathogenicity factor that potently restricts host gene expression. Among the β-CoV family, MERS-CoV is the most distantly related member to SARS-CoV-2, and the mechanism for host translation inhibition by MERS-CoV Nsp1 remains controversial. Herein, we show that MERS-CoV Nsp1 directly interacts with the 40S ribosomal subunit. Using cryogenic electron microscopy (cryo-EM), we report a 2.6-Å structure of the MERS-CoV Nsp1 bound to the human 40S ribosomal subunit. The extensive interactions between C-terminal domain of MERS-CoV Nsp1 and the mRNA entry channel of the 40S ribosomal subunit are critical for its translation inhibition function. This mechanism of MERS-CoV Nsp1 is strikingly similar to SARS-CoV and SARS-CoV-2 Nsp1, despite modest sequence conservation. Our results reveal that the mechanism of host translation inhibition is conserved across β-CoVs and highlight a potential therapeutic target for the development of antivirals that broadly restrict β-CoVs.

Exacerbation of Chronic Spontaneous Urticaria Following Coronavirus Disease 2019 (COVID-19) Vaccination in Omalizumab-Treated Patients

BACKGROUND

The rapid development and rollout of vaccines against coronavirus disease 2019 (COVID-19) has led to more than half of the world's population being vaccinated to date. Real-world data have reported various adverse cutaneous reactions, including delayed-onset urticaria, which was highly ranked as a common manifestation across studies. However, the impact of these novel mRNA or viral vector COVID-19 vaccines on preexisting chronic spontaneous urticaria (CSU) remains largely unknown.

OBJECTIVE

To investigate the impact of COVID-19 vaccination on the clinical status of patients with relatively stable CSU who are undergoing omalizumab treatment and to identify risk factors for exacerbation.

METHODS

We conducted a questionnaire-based cross-sectional study in a tertiary hospital. Adult patients with relatively stable CSU under regular omalizumab treatments who had received at least one COVID-19 vaccination were included.

RESULTS

There were 105 study subjects who received 230 COVID-19 vaccinations between March and December 2021. Fifteen patients (14.3%) experienced aggravation of urticaria at least once after COVID-19 vaccination. The demographics and clinical characteristics of the patients were comparable regardless of the exacerbation of CSU. However, case-level analysis revealed that the presence of urticaria (vs none) before vaccination (odds ratio [OR] = 4.99; 95% CI, 1.57-15.82) and the development of systemic reactogenicity (OR = 4.57; 95% CI, 1.62-12.90) were associated with a higher risk for exacerbation.

CONCLUSIONS

The novel COVID-19 vaccination induced exacerbation in more than one-tenth of patients with well-controlled CSU. The establishment of a proper management strategy during COVID-19 vaccination is necessary for patients with CSU.

SARS-CoV-2 main protease inhibitors: What is moving in the field of peptides and peptidomimetics?

The COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still affecting people worldwide. Despite the good degree of immunological protection achieved through vaccination, there are still severe cases that require effective antivirals. In this sense, two specific pharmaceutical preparations have been marketed already, the RdRp polymerase inhibitor molnupiravir and the main viral protease inhibitor nirmatrelvir (commercialized as Paxlovid, a combination with ritonavir). Nirmatrelvir is a peptidomimetic acting as orally available, covalent, and reversible inhibitor of SARS-CoV-2 main viral protease. The success of this compound has revitalized the search for new peptide and peptidomimetic protease inhibitors. This highlight collects some selected examples among those recently published in the field of SARS-CoV-2.

Single-dose rAAV5-based vaccine provides long-term protective immunity against SARS-CoV-2 and its variants

The COVID-19 pandemic, caused by the SARS-CoV-2 virus and its variants, has posed unprecedented challenges worldwide. Existing vaccines have limited effectiveness against SARS-CoV-2 variants. Therefore, novel vaccines to match mutated viral lineages by providing long-term protective immunity are urgently needed. We designed a recombinant adeno-associated virus 5 (rAAV5)-based vaccine (rAAV-COVID-19) by using the SARS-CoV-2 spike protein receptor binding domain (RBD-plus) sequence with both single-stranded (ssAAV5) and self-complementary (scAAV5) delivery vectors and found that it provides excellent protection from SARS-CoV-2 infection. A single-dose vaccination in mice induced a robust immune response; induced neutralizing antibody (NA) titers were maintained at a peak level of over 1:1024 more than a year post-injection and were accompanied by functional T-cell responses. Importantly, both ssAAV- and scAAV-based RBD-plus vaccines produced high levels of serum NAs against the circulating SARS-CoV-2 variants, including Alpha, Beta, Gamma and Delta. A SARS-CoV-2 virus challenge showed that the ssAAV5-RBD-plus vaccine protected both young and old mice from SARS-CoV-2 infection in the upper and lower respiratory tracts. Whole genome sequencing demonstrated that AAV vector DNA sequences were not found in the genomes of vaccinated mice one year after vaccination, demonstrating vaccine safety. These results suggest that the rAAV5-based vaccine is safe and effective against SARS-CoV-2 and several variants as it provides long-term protective immunity. This novel vaccine has a significant potential for development into a human prophylactic vaccination to help end the global pandemic.