Al-Aly and his colleagues compared 257,427 people who had their first infection with the virus that causes COVID-19 to a group of 38,926 people who had a second or subsequent infection, and 5.4 million people who had never been infected. Data for the study came from veterans in the Department of Veterans Affairs’ health care database.

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The results were published online in the journal Nature Portfolio as a key step in helping to evaluate and validate clinical research.

Results of the Study Conducted

Three COVID-19 experts not involved in the research raised two caveats, including how the study of veterans may or may not apply to the general population.

“It’s the first study to characterize the risks of reinfection,” says Eric Topol, MD, executive vice president of Scripps Research and editor-in-chief of Medscape. He points out that in comparison with the first infection, a second infection has twice the rate of death from any cause, twice the risk of heart or lung problems, and additional risks increased with each infection.

“Obviously these findings are worrisome since reinfection was quite rare before the Omicron wave hit, at 1% or less through the Delta variant wave. But now reinfections have become much more common,” he says.

Stakes may be Higher

Ali Mokdad, PhD, says that there maybe extra risks for the elderly, the immunocompromised, and people with other medical complications. He also said that the study was done in a good manner. Al-Aly and colleagues “have access to a good data, and they have done several studies.”

“It makes sense, and let me explain why,” Mokdad says. “When you have somebody who got COVID-19 the first time and was impacted by it, maybe someone who was older or who had a chronic condition, the next hit would also cause more damage.”

“That’s why you would expect some people would be more likely to have a harder second infection,” says Mokdad, an adjunct professor of epidemiology and a professor of health metrics sciences at the University of Washington in Seattle, USA.

“The best thing for you and for the general public – healthy or not, chronic condition or not – is not to get infected,” he says. “Go get your vaccines and your boosters, and wear a mask when you’re in a place that is crowded and you cannot keep a safe distance.”

A recent research suggests that BA.4 and BA.5 are four times more resistant to antibodies from vaccines than BA.2, a subvariant that became the dominant strain in the United States in April, replacing the original strain that had driven the winter wave across the country.

How to Differentiate Patients’ Risk Factors?

The ability of the BA.4 and BA.5 strains to reinfect people with strong immune systems in previous waves of COVID-19 has led some experts to call this latest strain even more contagious.

“When you look at that study, the big caveat is that veterans don’t resemble the general population,” says Amesh Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health in Baltimore.

“I don’t think you can generalize (the study) to everybody, but really for people that have risk factors for severe disease,” he says, because veterans tend to be older and have more health conditions.

He says a lot of people who get reinfected are testing positive at home. As a result, their cases don’t make it into research. In contrast, the veterans in the study were “people who for whatever reason wanted to get a formal test.”

As the virus has mutated away from the vaccines, the shots can still protect against severe illness, hospitalization, and death, but they are less able to protect against infection, Adalja says. “That’s also the case with prior immunity. If you were someone infected with BA.1 or Delta, for example, your ability to fend off the new variants, BA.4 and BA.5, may not be very high.”

The study shows why “it’s important to stay up to date with your vaccines,” he says, “and why we need to get better vaccines that are targeted to variants that are currently circulating.”

Adalja says that despite these caveats, the researchers used “a robust database” and a large study population, which “gives all of us confidence in the strength of the finding.”

COVID-19 Infection to Long COVID: The Impact

But here, the question is whether COVID-19 reinfection paves the way for increased risk of long COVID or not. So, Ziyad Al-Aly and his colleagues followed the patients for over 6 months and compared people who had one, two, three, or more infections to the non-infected group. Among the infected patients, about 13% had two infections, 0.76% had three infections, and 0.08%, or 246, people had four or more infections.

Compared to patients with a first COVID-19 infection, those who got a reinfection had more than double the risk of dying from any cause. Even though “the mechanisms underpinning the increased risks of death and adverse health outcomes in reinfection are not completely clear,” the authors say, “the findings highlight the consequences of reinfection and emphasize the importance of preventing reinfection SARS-CoV-2,” the COVID-19 virus that causes the infection.

Asked about the next step in their research, Al-Aly said, “BA.5 seems to be the main challenge looming ahead, and we are focused on trying to better understand it.” The Federal Drug Administration recommended that COVID-19 vaccine makers Pfizer and Moderna begin modifying what they currently offer so that their booster shots target the variants BA.4 and BA.5 types more accurately and evaluate these shots as early as mid-fall.

Source: Medindia