Effect of COVID-19 mRNA vaccination on COVID-19 severity during Omicron BA.4 and BA.5 dominance

In a recent study posted on medrex sib*Preprint Server, Researchers speculated an association between first-generation messenger ribonucleic acid (mRNA) vaccines (BNT162b2, mRNA-1273) and coronavirus disease 2019 (COVID-19)-related medical encounters.

The researchers conducted their study during a time when Omicron BA.4/BA.5 predominates in the United States (US) among immunocompromised adults. In addition, the investigators determined the epidemiological characteristics and severity of her hospitalized COVID-19 patient during the BA.4/BA.5 period, in which Omicron BA.1 and BA.2/BA.2.12.1 predominated. compared with the case

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.1 substrain became predominant in the United States by December 2021. It may offset the decline in vaccine efficacy (VE).

Since then, several more omicron subvariants have emerged, such as BA.4 and BA.5, which have a higher potential for immune escape than BA.1. From June 2022, the BA.4 and BA.5 substrains predominate in the United States. As new variants of concern (VOCs) emerge, continuous VE monitoring becomes critical to inform public health strategies and policies.

However, the September 2022 licensing of additional vaccine booster doses and a bivalent vaccine in the United States has complicated the estimation of VE. Similar to first-generation vaccines, bivalent vaccines contain an mRNA component that targets the ancestral virus and a novel component that targets the BA.4/BA.5 spike (S) protein.

Understanding the changing epidemiology of COVID-19 and VE will help interpret VE studies of recently approved bivalent vaccines.

About research

In this study, researchers obtained data from the VISION Network operated by the US Centers for Disease Control and Prevention (CDC) and conducted serial assessments of COVID-19 VE in emergency departments (ED)/urgent care (UC). The VISION network covers 268 hospitals, 292 emergency departments and 140 urgent care clinics in 10 US states.

The team considered two events for the VE analysis – i) ED/UC encounter and hospitalization with one or more COVID-19-like illness (CLI)-related discharge codes, and ii) performed within Molecular testing for SARS-CoV-2 14 days before the preponderance period of BA.4/BA.5 from 19 June to 20 August 2022.

The study cohort consisted of adults aged 18 years or older who required hospitalization for ≥24 hours or multiple hospitalizations within 30 days before hospital discharge. The team verified the participant’s COVID-19 vaccination status via the local Immunization Information System (IIS), Electronic Medical Records (EMR), and claims data.

The researchers used multivariate logistic regression to estimate the association between symptomatic laboratory-confirmed SARS-CoV-2 infection at ED/UC encounter or admission and vaccination status. Using the same model, they compared the odds of 2, 3, and 4 vaccination versus unvaccinated status in SARS-CoV-2-positive cases and SARS-CoV-2-negative controls. .

In addition to absolute VE, the team also determined relative VE (rVE) to assess the incremental benefit of receiving additional vaccine doses. In addition, we separately estimated the odds ratio (OR) between ED/UC encounter and hospitalization by age group (18–49 years, 50–64 years, and >65 years) for any combination of mRNA vaccines. Did.

Survey results

In all US states, first-generation COVID-19 vaccines remained effective against COVID-19-related hospitalizations and ICU admissions or in-hospital deaths. However, this protection waned rapidly, indicating that the most recent vaccination had the greatest impact during the period of BA.4/BA.5 dominance.

Regarding epidemiology, cases hospitalized during the BA.4/BA.5 predominance period tended to be less severe than during the BA.1 stage (64% vs. 36%), but were on average 8 years older. did.

Estimated VE for recipients who received the third or fourth dose of mRNA vaccine for ED/UC visits, hospitalizations, and ICU/death was higher than for recipients who received the second dose, whereas BA.4 decreased while the /BA.5 variant predominated. In addition, hospitalized patients had shorter hospital stays and were less likely to be admitted to the ICU or die during periods of BA.4/BA.5 predominance.

Interestingly, these VE estimates hold for both BA.4 and BA.5 sublineages with identical S proteins. These VE estimates also reflect herd immunity from previous infections, but high infection-induced immunity in the unvaccinated or unvaccinated groups blunts these VE estimates. may have been

Conclusion

This finding provides an important baseline for future VE analyses. The estimated VE during the period of BA.4/BA.5 dominance was lower than the previous VOC for all outcomes tested. However, the relative contribution of immune evasion from the new variant with other factors such as the effect of previous infection on her VE was unclear. VE also waned over several months with first-generation vaccines. In such cases, approved bivalent booster doses can provide increased protection against BA.4/BA.5. However, this requires further investigation.

*Important Notices

medRxiv publishes non-peer-reviewed, preliminary scientific reports and should not be considered conclusive, to guide clinical practice/health-related actions, or to be treated as established information .