COVID-19 hospitalizations 29 times more likely in unvaccinated individuals, CDC study suggests

By Angela Betsaida B. Laguipo, BSNAug 25 2021

As the coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread globally, countries to race to vaccinate as much of their populations as possible.

Getting inoculated against SARS-CoV-2 protects against getting severe COVID-19 or being hospitalized. In a new study by the U.S. Centers for Disease Control and Prevention (CDC), scientists noted that unvaccinated individuals are 29 times more likely to be hospitalized due to COVID-19 than those who were vaccinated.

Study: SARS-CoV-2 Infections and Hospitalizations Among Persons Aged ≥16 Years, by Vaccination Status — Los Angeles County, California, May 1–July 25, 2021. U.S. Centers for Disease Control and Prevention (CDC), Morbidity and Mortality Weekly Report (MMWR). Image Credit: LookerStudio / Shutterstock

The study, which appeared in CDC’s Morbidity and Mortality Weekly Report (MMWR), highlights the importance of getting vaccinated against COVID-19. Efforts to enhance COVID-19 vaccination coverage, in combination with other infection control measures, are crucial to prevent COVID-19-related hospitalizations and deaths.

COVID-19 vaccination

COVID-19 vaccines fully approved or currently authorized for use through the Emergency Use Authorization (EUA) from the Food and Drug Administration (FDA) are essential to control the COVID-19 pandemic.

To date, over 5 billion vaccine doses have been administered across the globe. In the past 28 days, more than 1 billion people received a dose of COVID-19 vaccines.

However, even with highly effective vaccines, some fully vaccinated persons may still get infected with SARS-CoV-2.

In the current study, the Los Angeles County Department of Public Health (LACDPH) used COVID-19 surveillance and California Immunization Registry 2 (CAIR2) data to describe infection and hospitalization rates between May 1 and July 25, 2021, by vaccination status.

Study findings

The CDC report analyzed 43,127 COVID-19 cases among people aged 16 and up in Los Angeles, which came from a total of 9.6 million residents in Los Angeles County who were tested for COVID-19. Of these, 10,895 people were fully vaccinated, while 1,431 were partially vaccinated. About 71.4 percent were unvaccinated.

Of the fully vaccinated people with COVID-19, 3 percent had been hospitalized, 0.5 percent were admitted to the intensive care unit (ICU), and 0.2 percent required a mechanical ventilator. In partially vaccinated people,  6 percent were hospitalized, 1 percent were admitted to the ICU, and 0.3 percent needed a mechanical ventilator.

Further, the age-adjusted incidence in unvaccinated people was 4.9 times that in fully vaccinated persons. The hospitalization rate in unvaccinated people was 29.2 times the rate in fully inoculated people.

The Delta variant is highly transmissible and became the predominant variant in Lost Angeles County. The variant has caused surges in cases in the country. The report says that during the May 1 to July 25, 2021 period, the percentages of people more than 16 years old that were infected increased from 8.6 percent to a staggering 91.2 percent in fully vaccinated individuals. The rate increased from 0 percent to 88.1 percent in partially vaccinated persons and 8.2 percent to 87.1 percent in unvaccinated people.

In July, when the Delta variant rose to predominance, cycle threshold values (ct values) were similar for unvaccinated, partially vaccinated, and vaccinated persons.

However, the findings suggest the protective effect of vaccines against severe COVID-19 and hospitalization when transmission of the Delta variant increased.

Ongoing surveillance to characterize postvaccination infections, hospitalizations, and deaths will be important to monitor vaccine effectiveness, particularly as new variants emerge,” the researchers noted in the paper.

To date, over 213.23 million cases of COVID-19 have been reported worldwide. Of these, 4.45 million people have died, while over 17.83 million new cases were noted in the past 28 days.