The crucial need for ongoing COVID-19 booster vaccination in vulnerable populations

By Dr. Priyom Bose, Ph.D.Jan 19 2024Reviewed by Benedette Cuffari, M.Sc.

The discovery and rapid implementation of mass vaccination has changed the course of the ongoing coronavirus disease 2019 (COVID-19) pandemic, which was caused by the emergence of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

To this end, a recent Nature Communications study investigates the need for prioritizing COVID-19 booster vaccination.

Study: Risk of COVID-19 death in adults who received booster COVID-19 vaccinations in England. Image Credit: SeventyFour / Shutterstock.com

Background

Mass global COVID-19 vaccination significantly reduced severe SARS-CoV-2 infection, mortality, and morbidity. Despite being vaccinated with two doses of the vaccine, some people continue to be at a higher risk of death due to COVID-19 .

Many studies have demonstrated that antibody levels decline over time, which has led to booster COVID-19 vaccination in an effort to restore protection against SARS-CoV-2.

In the United Kingdom, the first COVID-19 booster dose was offered to all adults three months after receiving the second vaccine dose. The health officials strategized that more COVID-19 booster doses would be offered to vulnerable groups, such as older adults, people with comorbidities, and healthcare workers who were at a higher risk of contracting severe SARS-CoV-2 infection, hospitalization, or death.

Consistent protection against COVID-19 could reduce the direct and indirect effects of the disease on healthcare services. Therefore, it is imperative to identify specific groups that are more vulnerable to severe outcomes from SARS-CoV-2 infection. These groups should be offered additional COVID-19 booster doses to ensure their protection against SARS-CoV-2.

About the study

The current study identified groups of adults who are at a greater risk of SARS-CoV-2-infection-related death, even after receiving a second booster dose of the vaccine. This group received the booster dose during England’s 2022 autumn booster campaign.

Here, individuals present in the 2021 census were included. The census was linked to the Personal Demographics Service (PDS) to obtain National Health Service (NHS) data.

Through the NHS number, individuals were further linked to the Office for National Statistics (ONS) death registrations and other electronic health records. Information about COVID-19 vaccination status was obtained from the National Immunization Management Service (NIMS).

Taken together, the linked dataset provided relevant information on about 52 million residents of England, which comprised about 92% of England’s population, according to the 2021 Census. The study cohort included individuals who received COVID-19 booster vaccine doses in England after September 1, 2022, and were between 50 and 100 years of age.

Study findings

A total of 14,651,440 adults with a mean age of 67.9 years were included in the analysis. The percentage of women present in this study population was marginally more than males and 90.4% were White British. 

Individuals with learning disabilities or Down’s syndrome, motor neuron disease, multiple sclerosis, Parkinson’s disease, pulmonary hypertension or fibrosis, cancer of blood and bone marrow, dementia or liver cirrhosis, lung or oral cancer, and myasthenia or Huntington’s disease were identified and independently linked to an increased risk of COVID-19 related death.

As compared to non-COVID-19 deaths, a greater number of deaths linked to SARS-CoV-2 infection was observed among individuals with cystic fibrosis, chronic kidney disease (CKD), rheumatoid arthritis, pulmonary hypotension, and systemic lupus erythematosus (SLE). 

The study findings strongly imply that individuals with these health conditions were at a greater risk of COVID-19 death relative to other causes of death. However, the increased rate of COVID-19 deaths was similar to or lower than the increased risk of deaths from other causes.

Consistent with previous reports, the current study indicated that the first COVID-19 booster vaccine significantly reduced severe infection, hospitalization rates, and deaths among individuals belonging to high-risk groups. Importantly, the risk of infection varies depending on multiple clinical factors, such as being in frequent contact with medical staff and residing in communal establishments.

Conclusions

A key strength of the study is the use of population-level linked data. Clinical risk factors that augmented the risk of death due to SARS-CoV-2 infection were identified. Another strength of the study is the use of non-COVID-19 deaths as a comparator to identify the risk factors. 

The current study also has some limitations, including the use of only the 2021 Census, as non-responders were not considered. Furthermore, the rate of hospitalization due to COVID-19 was not considered due to the lack of data.

The behavior of independent individuals, particularly those in compliance with social distancing recommendations, plays a crucial role in a diseased state. However, this information was not considered for the analysis. 

Despite these limitations, the current study identified the most vulnerable individuals who require subsequent COVID-19 boosters to protect them from severe outcomes. Thus, these individuals must be prioritized for subsequent booster vaccinations.