Incidence of SARS-CoV-2 Infection in Health Care Workers After a Single Dose of mRNA-1273 Vaccine

Coronavirus Disease 2019 Frequency After CoronaVac Vaccine: Ascovid Study

OBJECTIVE

It is accepted that the only way to end severe acute respiratory syndrome coronavirus 2 epidemic is through community vaccination. The frequency and clinical features of infection after vaccination are not known clearly. The aim of this study is to determine the frequency and clinical features of coronavirus disease 2019 seen after either the first or second dose of CoronaVac vaccination in healthcare workers and their relatives.

MATERIAL AND METHODS

This is a cross-sectional retrospective survey study. The study was carried out in 2013 volunteers, including 1903 (94.5%) healthcare workers and 110 (5.5%) relatives of healthcare workers. The frequency and clinical features of coronavirus disease 2019 before and after the first or second dose of CoronaVac vaccination were retrospectively evaluated using an online questionnaire conducted in July 2021.

RESULTS

A total of 2013 people, 1312 women and 701 men, participated in the study. Of these individuals, 245 (12.1%) were polymerase chain reaction positive for coronavirus disease 2019 before vaccination. Of this group, 185 (75.5% of polymerase chain reaction positives and 9.1% of the whole population) received home-based therapy, while 38 (15.5%) received hospital admission. Asymptomatic polymerase chain reaction positivity before vaccination was seen in 22 (9%) individuals. There were 177 (8.8%) participants who developed polymerase chain reaction positivity at any time after vaccination. In 129 (72.8%) of these participants, polymerase chain reaction positivity occurred 21 days after the second dose of vaccine. While the number of patients hospitalized before vaccination was 38 (15.5% of the polymerase chain reaction positivity group and 1.89% of the general population), the number of patients hospitalized after the vaccination was 17 (10.1% of the polymerase chain reaction positivity group and 0.80% of the general population). The decrease in hospitalization proportion was statistically significant (P = .002).

CONCLUSION

The frequency of coronavirus disease 2019, severe illness, and hospitalization rates were found to be lower in postvaccination period. The vaccine is effective in preventing coronavirus disease 2019 and severe disease.

Impact of SARS-CoV-2 vaccination in healthcare workers in a network of clinics in Latin America

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Frontline employees have been severely affected by COVID-19.

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This study assessed the effect of vaccination among healthcare staff in Colombia.

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COVID-19 infections in Colombia increased dramatically during early 2021.

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Vaccination rollout in frontline personnel reduced the incidence of new cases among healthcare workers, in contrast to the general population.

Objectives

Healthcare workers (HCWs) have been severely affected in terms of both morbidity and mortality since the beginning of the COVID-19 pandemic. During the first few months of 2021, Colombia experienced a surge in positive cases. This study aimed to evaluate the effect of vaccination on the incidence of new positive cases in HCWs.

Design

This was a retrospective cohort study of frontline employees in a network of clinics in Colombia, who were prioritized for COVID-19 vaccination from February to March 2021.

Results

Our findings were consistent with recent reports. During early 2020, the incidence of HCWs positively diagnosed with COVID-19 in Colombia was higher than that for the general population. With the start of the national vaccination program, the incidence among HCWs decreased from April 2021, while that for the general population remained relatively unchanged. Our study identified lower infection rates among HCWs during April (odds ratio [OR], 0.72 [95% CI 0.58–0.90]; p < 0.01) and May (odds ratio [OR], 0.25 [95% CI 0.18–0.36]; p < 0.01).

Conclusions

COVID-19 vaccination rollout in Colombia during early 2021 led to a decrease in the incidence of new positive cases among HCWs, in contrast to a continuing surge in the general population. Our findings suggested that COVID-19 vaccination provided adequate immunity, which guaranteed protection to HCWs.

Covid-19: virology, variants, and vaccines

As of 25 January 2022, over 349 million individuals have received a confirmed diagnosis of covid-19, with over 5.59 million confirmed deaths associated with the SARS-CoV-2 virus. The covid-19 pandemic has prompted an extensive global effort to study the molecular evolution of the virus and develop vaccines to prevent its spread. Although rigorous determination of SARS-CoV-2 infectivity remains elusive, owing to the continuous evolution of the virus, steps have been made to understand its genome, structure, and emerging genetic mutations. The SARS-CoV-2 genome is composed of several open reading frames and structural proteins, including the spike protein, which is essential for entry into host cells. As of 25 January 2022, the World Health Organization has reported five variants of concern, two variants of interest, and three variants under monitoring. Additional sublineages have since been identified, and are being monitored. The mutations harboured in these variants confer an increased transmissibility, severity of disease, and escape from neutralising antibodies compared with the primary strain. The current vaccine strategy, including booster doses, provides protection from severe disease. As of 24 January 2022, 33 vaccines have been approved for use in 197 countries. In this review, we discuss the genetics, structure, and transmission methods of SARS-CoV-2 and its variants, highlighting how mutations provide enhanced abilities to spread and inflict disease. This review also outlines the vaccines currently in use around the world, providing evidence for every vaccine's immunogenicity and effectiveness.

SARS-CoV-2 spike E156G/Δ157-158 mutations contribute to increased infectivity and immune escape

This study underscores the significance of NTD-specific SARS-CoV-2 spike mutations E156G/Δ157-158 in determining virion infectivity and neutralization by vaccine-elicited antibodies.

Breakthrough infections by emerging SARS-CoV-2 variants raise significant concerns. Here, we sequence-characterized the spike gene from breakthrough infections that corresponded to B.1.617 sublineage. Delineating the functional impact of spike mutations revealed that N-terminal domain (NTD)-specific E156G/Δ157-158 contributed to increased infectivity and reduced sensitivity to vaccine-induced antibodies. A six-nucleotide deletion (467–472) in the spike-coding region introduced this change in the NTD. We confirmed the presence of E156G/Δ157-158 from cases concurrently screened, in addition to other circulating spike (S1) mutations such as T19R, T95I, L452R, E484Q, and D614G. Notably, E156G/Δ157-158 was present in more than 90% of the sequences reported from the USA and UK in October 2021. The spike-pseudotyped viruses bearing a combination of E156G/Δ157-158 and L452R exhibited higher infectivity and reduced sensitivity to neutralization. Notwithstanding, the post-recovery plasma robustly neutralized viral particles bearing the mutant spike. When the spike harbored E156G/Δ157-158 along with L452R and E484Q, increased cell-to-cell fusion was also observed, suggesting a combinatorial effect of these mutations. Our study underscores the importance of non-RBD changes in determining infectivity and immune escape.

A systematic review of methodological approaches for evaluating real-world effectiveness of COVID-19 vaccines: Advising resource-constrained settings

Real-world effectiveness studies are important for monitoring performance of COVID-19 vaccination programmes and informing COVID-19 prevention and control policies. We aimed to synthesise methodological approaches used in COVID-19 vaccine effectiveness studies, in order to evaluate which approaches are most appropriate to implement in low- and middle-income countries (LMICs). For this rapid systematic review, we searched PubMed and Scopus for articles published from inception to July 7, 2021, without language restrictions. We included any type of peer-reviewed observational study measuring COVID-19 vaccine effectiveness, for any population. We excluded randomised control trials and modelling studies. All data used in the analysis were extracted from included papers. We used a standardised data extraction form, modified from STrengthening the Reporting of OBservational studies in Epidemiology (STROBE). Study quality was assessed using the REal Life EVidence AssessmeNt Tool (RELEVANT) tool. This study is registered with PROSPERO, CRD42021264658. Our search identified 3,327 studies, of which 42 were eligible for analysis. Most studies (97.5%) were conducted in high-income countries and the majority assessed mRNA vaccines (78% mRNA only, 17% mRNA and viral vector, 2.5% viral vector, 2.5% inactivated vaccine). Thirty-five of the studies (83%) used a cohort study design. Across studies, short follow-up time and limited assessment and mitigation of potential confounders, including previous SARS-CoV-2 infection and healthcare seeking behaviour, were major limitations. This review summarises methodological approaches for evaluating real-world effectiveness of COVID-19 vaccines and highlights the lack of such studies in LMICs, as well as the importance of context-specific vaccine effectiveness data. Further research in LMICs will refine guidance for conducting real-world COVID-19 vaccine effectiveness studies in resource-constrained settings.

Crossing the Rubicon: A fine line between waiting and vaccinating adolescents against COVID-19

Several countries with advanced adult COVID-19 immunisation programmes have already started vaccinating adolescents with an mRNA vaccine that recently received emergency use authorisation for 12–15 year-olds. The decision to vaccinate adolescents remains highly divisive among parents, clinicians, politicians and policy makers. There are very few downsides to immunising adolescents with a safe and effective COVID-19 vaccine because that would significantly reduce their risk of COVID-19 and all its complications. Based on current evidence, however, adolescents have a very low risk of severe or fatal COVID-19, even among those with comorbidities, or rare complications such as long COVID or Paediatric Multisystem Inflammatory Syndrome (PIMS-TS), a hyperinflammatory syndrome temporally associated with SARS-CoV-2. Additionally, currently authorised vaccines are very reactogenic and have limited post-marketing population-level safety data in adolescents and young adults, but these are emerging from countries that have forged ahead with vaccinating adolescents. Countries that have yet to make a recommendation can afford to wait until there is sufficient information to make informed decisions on the risk-benefits of vaccinating adolescents with current and future COVID-19 vaccines. Alternatives to two-dose vaccination in adolescents may include a single dose or a reduced dose schedule as is currently being trialled in younger children.