In a recent study published in JAMA network open, researchers have shown that the protein recombinant coronavirus disease 2019 (COVID-19) vaccine Novavax ( We discuss the effectiveness of the primary cycle of NVX-CoV2373). .
study: Estimated efficacy of the first cycle of recombinant protein vaccine NVX-CoV2373 against novel coronavirus infection. Image credit: Vladimka Production / Shutterstock.com
background
High morbidity and mortality during the coronavirus disease (COVID-19) pandemic led to a tremendous effort to rapidly develop a vaccine against SARS-CoV-2. These efforts culminated in the development of adenoviral vectors, inactivated viruses, protein recombination, and messenger ribonucleic acid (mRNA) vaccines.
A significant proportion of Europe’s population has received primary vaccination against COVID-19 by the end of 2022. In Italy, most of the population has completed the primary vaccination series with mRNA vaccines.
Despite the widespread availability of vaccines, the emergence of novel virus variants that can evade vaccine- or infection-induced immunity, combined with the natural decline of vaccine-induced immunity, may result in the persistence of SARS-CoV-2 in humans. caused an infection. Given the rapid evolution of SARS-CoV-2 and the emergence of new Omicron subvariants, it is important to estimate the effectiveness of alternative vaccines in preventing infection.
About research
In this study, researchers used general population data on vaccinations administered and vaccine-related demographic and clinical information from the Italian Vaccine Registry. These data were used to evaluate the efficacy of her NVX-CoV2373 in preventing symptomatic novel coronavirus disease (COVID-19) and SARS-CoV-2 infection during the Omicron-dominant period. .
The study used data on COVID-19 outcomes and SARS-CoV-2 infections confirmed through antigen tests or polymerase chain reaction (PCR) assays from the National Integrated Surveillance System. The study population consisted of a retrospective cohort of all adults who completed a primary vaccination cycle with the protein recombinant vaccine NVX-CoV2373 between February and September 2022.
A minimum follow-up period of 3 weeks was ensured for each participant. The main Omicron substrains that circulated during the study period were BA.2 and BA.5. Persons with a history of SARS-CoV-2 infection or who had completed primary vaccination with other vaccines were excluded from the study.
The outcomes investigated were the incidence or risk of symptomatic coronavirus disease (COVID-19) and SARS-CoV-2 infection confirmed by PCR or antigen testing. The risk of infection or symptomatic disease was assessed at different stages, including after partial and full vaccination.
The partial vaccination period begins 15 days after the first vaccination and begins 15 days after the second vaccination, based on the assumption that protection during the first 2 weeks after the first vaccination is similar to unvaccinated. It ended two weeks after vaccination. Similarly, the full vaccination phase began 15 days after the administration of the second and last primary vaccination.
Incidence rate ratios were calculated for both primary endpoints. All analyzes were adjusted for major confounders such as age, sex, and region of residence.
research result
The recombinant protein vaccine NVX-CoV2373 was effective in preventing symptomatic COVID-19 and SARS-CoV-2 infections when the Omicron variant and its subvariants were the predominant circulating strains.
The estimated efficacy of NVX-CoV2373 in protecting against SARS-CoV-2 infection decreased from 41% to 28% in the 4 months following completion of the primary vaccination cycle. The efficacy of the primary vaccination cycle was relatively high with 50% protection against symptomatic infection.
Initial clinical trials of NVX-CoV2373 reported 95% vaccine efficacy against the ancestral SARS-CoV-2 variant and 85% efficacy against the SARS-CoV-2α variant. These vaccine efficacy rates were comparable to those reported for mRNA vaccines against the same variants.
One of the study’s limitations is that the population that opted for the recombinant protein vaccine was small, making it impossible to assess the vaccine’s effectiveness in preventing hospitalization and death. Due to the small sample size, it was also not possible to stratify the results by age.
The study population also consisted of individuals younger than 80 years without significant comorbidities, so the results cannot be generalized to a larger population.
conclusion
The results of this study suggest that the NVX-CoV2373 vaccine is effective in reducing the risk of SARS-CoV-2 infection and symptomatic COVID-19. Protection against SARS-CoV-2 infection decreased over 4 months after completion of the primary vaccination round. However, protection against symptomatic coronavirus disease (COVID-19) remained stable.
NVX-CoV2373 was recently approved as a booster vaccine, so the efficacy of that booster shot has not yet been evaluated.
Reference magazines:
- Mateo Urdiales, A., Sacco, C., Petrone, D., other. (2023). Estimated primary cycle efficacy of recombinant protein vaccine NVX-CoV2373 against novel coronavirus infection. JAMA network open 6(Ten). doi:10.1001/jamanetworkopen.2023.36854
