Repeated vaccination against COVID-19 may improve public health outcomes

Recent research posted on medRxiv* Preprint servers suggest that repeated vaccinations at frequent intervals may improve the efficacy of coronavirus disease 2019 (COVID-19) vaccines and the trajectory of the pandemic.

study: Impact of vaccination frequency on COVID-19 public health outcomes: a model-based analysis. Image Credit: M-Foto/Shutterstock

Background

A COVID-19 vaccine developed in record time has reduced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, symptomatic illness, hospitalizations, and deaths in the early stages of global vaccine deployment. has been shown to be highly effective in the prevention of

Despite strong efficacy against wild-type strains of SARS-CoV-2, nearly all COVID-19 vaccines have shown limited efficacy against emerging SARS-CoV-2 variants that demonstrate increased transmissibility and immune evasion. showing a significant decline. The greatest declines in vaccine efficacy have been observed for SARS-CoV-2 variants (VOCs) of concern, including the alpha, beta, gamma, delta, and omicron VOCs.

To increase vaccine efficacy and achieve strong and durable neutralizing antibody responses, most countries around the world have introduced booster vaccines. Actual studies have shown that booster doses are effective against VOCs.

In the current study, scientists use an agent-based modeling framework in combination with the output of population-level pharmacokinetic models of neutralizing antibody responses to explore the relationship between booster frequency and vaccine efficacy. .

More specifically, scientists are examining population heterogeneity in vaccine-mediated protection against infection and the impact of viral immune evasion on vaccine efficacy. This information was then used to develop strategies to improve vaccine efficacy by altering dosing intervals.

Effect of Booster Frequency on Vaccine Efficacy

Assuming that 50% of the population received regular boosters, the study model predicted infection frequency and mortality risk for vaccinated and unvaccinated individuals.

The model estimated that individuals who received one booster dose were predicted to experience an average of 1.5 infections each year, while unvaccinated individuals were expected to experience two or more infections each year. it was done. The risk of death in unvaccinated individuals was predicted to be twice as high compared to boosted individuals.

Infection frequency was predicted to decrease with induction of booster frequency. An individual who received her four boosters was expected to never become infected with SARS-CoV-2 in one year. Over the 10-year simulation period, no infection was observed in her 80% of these individuals.

An annual mortality risk greater than 0.1% was predicted in 2% of the 4 individuals with dose escalation. By comparison, approximately 15% of unvaccinated individuals were predicted to have the same risk of death.

Frequency of breakthrough infections

Regarding breakthrough infections in boosted individuals, approximately 17% of the four dose-boosted individuals were predicted to become infected at any frequency over 10 years. Similarly, approximately 10% of these individuals were expected to become infected at least every other year.

A short antibody half-life of less than 50 days has been identified as a major risk factor for breakthrough infections. Models predict that her six vaccinations per year may reduce the risk of infection in high-risk populations.

Booster vaccination and ommicron contagiousness

High adherence to frequent boosts significantly reduced the impact of the pandemic at the population level.

Given the highly contagious SARS-CoV-2 Omicron variant, approximately 90% adherence to booster doses every 3 months was predicted to completely arrest its spread.

With uncontrolled spread of the virus, increased vaccination coverage and frequency were projected to significantly reduce annual mortality.

Booster vaccination and antibody kinetics

Because the Moderna COVID-19 vaccine elicits a less durable antibody response than natural infection, scientists believe that future COVID-19 vaccines will be more effective than natural in that they elicit robust and durable antibody responses. assumed to have efficacy equal to or greater than infection.

Such future vaccine boosters, with only three doses per year, were expected to completely prevent infection in vaccinated individuals.

By simulating conditions similar to the delta wave in the United States, scientists hope to reduce the spread of this deadly VOC by boosting just 48% of Americans who receive primary vaccination by the summer of 2021. suggested that it may have been possible to significantly reduce

Significance of research

Current research suggests that repeated boosters at frequent intervals could improve the efficacy of COVID-19 vaccines and control the trajectory of the pandemic.Nonetheless, clinical studies on safety and safety effectiveness of Repeat vaccinations are needed to confirm the predictions made in this study.

*Important Notices

medrex sib We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.