New COVID Vaccine 54% Effective at Preventing Symptoms

2 min read

Feb. 2, 2024 – If you’re in the minority of Americans who received the most recent COVID-19 vaccination, chances are you’re in the majority not experiencing any COVID symptoms now or in the near future. 

The CDC announced the first numbers on the XBB.1.5 monovalent vaccines protection against developing symptoms, including from the JN.1 variant. Among those vaccinated recently, immunization provided 54% more protection against symptoms compared to unvaccinated Americans. 

“It’s really exciting data,” said Luis Ostrosky, MD, chief of infectious diseases and epidemiology with UTHealth Houston and Memorial Hermann in Texas. “It’s really interesting to see this kind of a real-world study, not a clinical trial.” 

The researchers took people who tested for COVID and then asked them about vaccine history. The bad news is only 22% of American adults have received the updated vaccine. 

The current shot protects against a number of COVID variants, including the XBB variants that predominated this past fall and the JN.1 variant that became most common starting in December.

That is good news for those who wish to avoid COVID symptoms such as fever or chills, muscle or body aches, and shortness of breath. 

Although some might think 54% does not sound like a high percentage, it’s in line with the 60% or so protection against symptoms associated with the flu vaccine each year, Ostrosky said. 

“The current vaccine is a really good match for JN.1, immunologically speaking,” Ostrosky said. However, “we’re very concerned about the lack of uptake of this vaccine. But it’s never too late, right?”

Public health experts have pointed out for a long time that the COVID vaccines authorized in September 2023 are less effective at preventing transmission of the virus from one person to another. But among the vaccinated exposed to COVID, immunization is associated with much lower chances of developing serious illness, requiring hospitalization or dying from COVID. 

The 54% vaccine effectiveness is based on a study from September through earlier this month of 9,222 COVID tests in the Community Access to Testing SARS-CoV-2 pharmacy testing program. Both CVS and Walgreens participate in the program by reporting their COVID-19 testing results. 

The effectiveness of the vaccine was tested a median 52 to 60 days and up to 119 days after vaccination. Researchers compared vaccinated adults to unvaccinated others. All participants were immunocompetent, meaning they did not have underlying immune conditions that placed them at higher risk for severe COVID illness. 

The CDC reported the full results in Thursday’s Morbidity and Mortality Weekly Report (MMWR). 

If you’re wondering about who is eligible for the vaccine, including when babies can get the COVID vaccine, the CDC recommends vaccination for all Americans 6 months and older. 

Later this year the CDC also plans to release information on how effective the COVID vaccines are against preventing people from seeking medical care from a doctor or hospital because of severe symptoms.