Research suggests that new coronavirus vaccination is “not up-to-date” and is associated with reduced risk of infection

The U.S. Centers for Disease Control and Prevention (CDC) has updated its guidance on coronavirus disease (COVID-19) vaccination in April 2023. All persons aged 6 years and older who had received at least one dose of her bivalent vaccine for COVID-19 and whose COVID-19 vaccination was considered “current”. Conversely, those who had not received a single dose of the novel coronavirus disease (COVID-19) bivalent vaccine were considered not “current”.

Study: 2019 coronavirus disease (COVID-19) risk in people with and without up-to-date knowledge of COVID-19 vaccination. Image credit: ONGUSHI / Shutterstock.com study: Risk of 2019 coronavirus disease (COVID-19) among those with and without up-to-date information on COVID-19 vaccination. Image credit: ONGUSHI / Shutterstock.com

*Important Notices: medRxiv Publishes preliminary scientific reports that have not been peer-reviewed and should therefore not be considered definitive, to guide clinical practice or health-related actions, or to be treated as established information. not.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) XBB variant was the predominant epidemic strain, although recent studies have failed to document the efficacy of bivalent vaccines. Given that these virus variants remain the predominant circulating strains, ‘modern’ individuals who received a non-conclusive vaccine were more likely to be affected by the novel coronavirus than those with a ‘non-modern’ vaccine. It is reasonable to ask whether people are protected from infectious diseases. ‘ respondent.

To address this issue, recent research medRxiv* The preprint server investigates whether “latest” individuals are at higher risk of COVID-19 than “latest” individuals.

About research

The current retrospective cohort study was conducted at the Cleveland Clinic Health System (CCHS). The bivalent messenger ribonucleic acid (mRNA) vaccine for COVID-19 was first made available to employees on September 12, 2022. The start date for this study was his January 23, 2023, the date his XBB strain first became a major epidemic strain in Ohio.

Study participants were CCHS employees everywhere as of September 12, 2022 and remained employed when the XBB lineage became dominant. Individuals were excluded if age and gender data were not available.

The outcome variable was time to novel coronavirus disease (COVID-19), defined as SARS-CoV-2 nucleic acid amplification test (NAAT) positive. Study participants were closely monitored until May 10, 2023, allowing results to be evaluated within up to 100 days of study initiation.

Main findings

A total of 48,344 participants were considered, of whom 1,445 were censored by dismissal. Within the study cohort, 12,841 people were “up to date” on COVID-19 vaccination by the end of the study.

Of these, 11,187 received the Pfizer vaccine and 1,654 received the Moderna vaccine. A total of 1,475 employees were infected with SARS-CoV-2 during the 100-day investigation period.

The population was relatively young, with an average age of 43 years. Approximately 46% had a history of COVID-19, and 34% were infected with the Omicron variant. Additionally, 87% of the study cohort had received at least one vaccination, and 92% had been exposed to SARS-CoV-2 through infection or vaccination.

The risk of COVID-19 was lower in the “not updated” group compared to the “updated” group. Analysis of the tertiles of propensity to be tested for SARS-CoV-2 infection showed that the group who did not get “up to date” was not more likely to be infected with COVID-19.

A COVID-19 risk categorization was better served by considering past infections. A significantly lower risk of novel coronavirus disease (COVID-19) was observed in individuals least affected by the Omicron BQ or BA.4/BA.5 variants. However, when stratified by date of most recent infection, no clear difference was observed between ‘recent’ and ‘non-recent’ individuals.

One reason that being “current”, as defined by the CDC, is not associated with reduced risk of COVID-19 is that the bivalent vaccine was less effective against the omicron variant XBB strain. . Another reason may be that the CDC definition ignores the protective effects of immunity acquired from previous infections.

Conclusion

A current study reports that if vaccination is not ‘up to date’ it is associated with a lower risk of COVID-19 than if it is ‘up to date’. These findings demonstrate that efficacy declines over time and that it is difficult to assess vaccine protection when risk classification methods are based solely on exposure to vaccines of questionable efficacy. is showing.

The main strengths of this study are the large sample size and the fact that it was conducted in a country that has invested significant resources in accurately tracking the progression of the pandemic. In addition, the methodology treating vaccination status as a time-dependent covariate enabled real-time determination of vaccine efficacy.

The present study focused on all detected infections and did not distinguish between asymptomatic and symptomatic infections. Some asymptomatic and mildly symptomatic infections may have been mistakenly ignored, resulting in incomplete information about previous COVID-19 infections.

Furthermore, the question of whether “being up to date” reduces disease severity could not be studied because severe disease is rare. Finally, due to the young age of the study population, we were unable to study the effects on immunocompromised patients.

*Important Notices: medRxiv Publishes preliminary scientific reports that have not been peer-reviewed and should therefore not be considered definitive, to guide clinical practice or health-related actions, or to be treated as established information. not.

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