The vaccine provides complete protection against the serious effects of COVID-19 in the U.S. Coast Guard

The severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2) which has caused the coronavirus pandemic 2019 (COVID-19) has spread all over the world and been affecting more than 261 million people. It has also killed more than 5.2 million people. While anyone can be affected by SARS-CoV-2 at any point in time but certain individuals are more likely to be affected.

Study: Efficacy of Vaccination against Reported SARS-CoV-2 Infection in the United States Coast Guard Personnel between May and August 2021: A Study of Time-Series. Image Credit: Aleksander Malivuk /

The U.S. Coast Guard (CG) began to immunize its personnel in December of 2020 shortly after receiving an emergency use authorization (EUA), from the United States Food and Drug Administration for two messenger ribonucleic acids (mRNA)-based vaccines manufactured at Moderna and Pfizer. On August 24, 2021, COVID-19 vaccination for military personnel was made mandatory by the U.S. Secretary of Defense. From August 26, 2021, the Commandant of the CG also took the same approach for CG Active Duty and Ready Reserve personnel.

While reports of COVID-19’s vaccine effectiveness (VE) have been published since their approval however, none of these studies have been focused on VE in the military population.

Vaccine efficacy in the U.S. CG

In a recent paper published on the preprint server medRxiv* researchers conducted a time-series analysis to evaluate the effectiveness of COVID-19 vaccine in the U.S. CG against SARS-CoV-2 infection. CG who were vaccinated with any of the approved vaccines and those who were positive for COVID-19 between May to August 2021 were included in the study.

Information on CG was positive for SARS-CoV-2 was obtained from Coast Guard Personnel Accountability and Assessment System (CGPAAS), and information on the status of vaccination of CG were collected from a wide immunization registry.

Study findings

The researchers estimated that VE among CG staff was 82.6 percent in May 2021. The figure climbed to 89.0% in June 2021. VE fell to 62.7% by the end of the study in August 2021.

In fully vaccine-vaccinated CGs who were given either the Pfizer nor Moderna vaccines, COVID-19 breakthrough cases remained at just 1%. No severe outcome like death or hospitalization was reported for CG members who were fully vaccinated.

The study also revealed that the rate of cases of COVID-19 that were breakthrough was significantly higher in CG patients who had received the Johnson & Johnson vaccine during the first three months of the study. The rate increased to almost two-and-a-half times the rate observed with Moderna or Pfizer recipients.

Additional analyses of the geographic area (Atlantic and Pacific) revealed that the VE total for June 2021 was greater with respect to the estimation of regional VE or total vaccination. The pacific region had more complete vaccinations and fewer cases of SARS/CoV-2 infection.

Areas within the U.S. Coast Guard (Source CGPAAS).

Older individuals had wide variation in VE. They had a 100 percent VE for the initial month of May 2021. However, it dropped by -0.1 in June and 5.5% in August 2021.

In the initial study phase, the researchers noted less reported cases contrast to cases reported in August and July. The older age group had the lowest VE, suggesting that the effectiveness of mRNA vaccinations can decrease as people age.

This is one of the main limitations of the current study. It could lead to being incorrectly classified as not fully vaccine-free. Additionally, the time since vaccination was not considered in the study.


The study found that CG members’ VE dropped in the summer of 2021 because of the spread and severity of COVID-19. They suggested that a higher level of vaccination for military personnel could extend the benefits of disease prevention that were observed in this study.

The CG plans to keep monitoring and estimating VE to keep track of other important clinical and public health measures that are related to COVID-19.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

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Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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