The protection provided by vaccines and prior infection has greatly improved COVID outcomes since the early days of the pandemic, and reinfections are generally less severe than in early ones. Yet each new infection carries a risk of medical problems, including hospitalization, death and prolonged COVID-19, according to preliminary data from a study of patients in the Veterans Affairs health system.
Doctors say this is a timely finding, as the more infectious omicron subvariants BA.4 and BA.5 tend to spread and are expected to make reinfection more common.
Eric J., founder and director of the Scripps Research Translational Institute, a biomedical research facility in La Jolla, Calif. VA research is the first to look at reinfection in a significant way, says Topol. “These are really large samples and they have good statisticians,” he adds.
The study found that re-infections of COVID may result in less severe blows than in the initial ones, but each infection creates some new opportunity for the virus to harm your body. So over time, your cumulative risk of developing problems increases with each infection.
The risk of developing medical issues such as lung and heart problems is highest in the first 30 days after infection. For most conditions those risks remain elevated for up to six months and increase with each subsequent infection. For example, out of 100 people with reinfection and 100 who had only one infection, five more people with reinfection developed lung or respiratory problems or heart problems within a six-month period.
“Re-infection may be mild but it still adds risk,” says Ziad Al-Ali, chief of research and development at the VA St. Louis Health Care System and a clinical epidemiologist at Washington University in St. Louis.
The researchers compared the electronic health records of three groups of people: more than 257,000 people with a confirmed COVID-19 infection; more than 38,900 people with two or more infections; and a control group of more than 5.3 million who did not have a Covid-19 infection. The majority of people with reinfection — 92% — had two infections. The study has not yet been peer reviewed and is under review for publication.
One caveat of the VA study is that their patients are older and have many concomitant diseases, says Amesh A., a senior scholar at the Johns Hopkins Center for Health Security. Adalja, who was not involved in the VA study. For example, an otherwise healthy 18-year-old is “unlikely to add significantly to their risk” in the same way as an older person with underlying health problems, Dr. Adalja says.
And VA patients who went to the doctor for reinfection were more likely to have symptoms than those who did not seek medical care and were not included in the study, Dr. Adalja notes.
Still, “it’s better not to be re-infected than to be re-infected,” he says. “Re-infections are not something you want, even if they are going to be ubiquitous.”
According to Dr. Topol, with the more infectious and immune-hiding oomicron subvariants BA.4 and BA.5, re-infection counts will increase as they become more common.
“We are heading into the worst zone of re-infection we have seen since the pandemic began,” Dr. Topol says.
The US Centers for Disease Control and Prevention does not track reinfections. New data from the United Kingdom’s Office for National Statistics found that the risk of being reinfected with COVID-19 was seven times higher when the Omicron variant was circulating compared to when Delta was the dominant strain.
Looking at the period between July 2020 and June 2022, the ONS also found that younger people were more likely to get COVID again, as were those without vaccinations.
The VA study did not look at the comparative severity of reinfection. Other research has found that the severity of reinfection is much lower than earlier COVID-19 infections, says Leith Abu-Raddad, a professor of infectious disease epidemiology at Weill Cornell Medicine-Qatar, which specializes in COVID-19 re-infection in Qatar. do research on.
Dr. Abu-Raddad says the VA research sheds light on the ways in which repeated cases of covid can pose a health risk. “The more infections we have, the more damage we are going to do and the longer we are likely to have COVID,” says Dr. Abu-Raddad of VA Research.
Doctors do not yet know exactly how reinfection affects the body. Immunity to an earlier infection or vaccine may reduce the severity of COVID as the immune system is familiar with the virus and can handle it better a second or third time.
But if the first COVID-19 infection weakens the immune system and causes problems in one or more organs—that may not be noticeable at first—then subsequent infections can cause further damage to those organs. so that the problems become noticeable.
About the second group, Dr. Al-Aly says, “they manifest the disease when people get re-infected.” Different people may experience reinfection in different ways.