Those with systemic lupus erythematosus, or SLE, who received a "booster" dose of the SARS-CoV-2 vaccine after receiving the full dosage are about half as likely to experience a subsequent "breakthrough" COVID-19 infection, according to a recent study.

This study was published in The Lancet Rheumatology journal on July 12. The discovery, according to researchers, should provide comfort to the more than 200,000 Americans who suffer from SLE, a disorder where the immune system of the body unintentionally targets its own healthy tissues, particularly joints and skin.

They are more susceptible to infections, such as SARS-CoV-2, when taking immune-suppressing medications, like steroids, which are required to control the disease's symptoms.

The current study, led by doctors from NYU Grossman School of Medicine, followed 163 fully immunised men and women receiving SLE treatment at its affiliated institutions in New York City.

Given that more than half of the participants were using at least one immune-suppressive drug for their SLE, the researchers wanted to determine who contracted the virus over a period of at least six months. Prior to June 2021, all had gotten some combination of vaccinations made by Pfizer, Moderna, or Johnson & Johnson, but only 125 had received a booster or third dosage.

The study revealed that 44 vaccinated SLE patients had experienced breakthrough infections by the conclusion of the monitoring period (April 24, 2022), with two of them necessitating hospitalisation (but both surviving their infection).

28 of 125, or 22 per cent, of those who had breakthrough infections, had had a booster, compared to 16 of 38, or 42 per cent, who had not. Investigators found it noteworthy that the bulk of breakthrough infections (42 of 44) took place after the city discovered its first case of the extremely contagious omicron strain on December 2, 2021.

Another significant study finding was among the 57 patients who consented to have two blood antibody levels checked: once after the initial vaccination and once after the booster shot.

Even immunosuppressed individuals who did not respond to the first round of vaccination experienced an instantaneous increase in antibody levels after receiving a booster dose, according to research.

Previous studies had revealed that these antibody levels were lower in many first immunised individuals with rheumatic disorders, including SLE, who were using immunosuppressive medications, which raised concerns about the possibility of declining COVID-19 immunity over time.

However, the study's findings revealed that neither group was any more protected from a breakthrough infection than individuals with lower levels of the spike-protein antibodies, which are required to block the SARS-Cov-2 "spike" protein and stop the virus from invading human cells.

Yet, according to an earlier study, higher antibody levels in completely immunised lupus patients strengthened important indicators of long-term immunity, which may help to explain why those with breakthrough infections do not experience severe disease.

According to the co-lead investigator and rheumatologist Amit Saxena, MD, MS, "our trial results offer persons with systemic lupus erythematosus clinical confirmation that immunisations are extremely efficient at preventing severe COVID-19, despite their elevated risk of contracting the disease."

An additional, double layer of protection against a breakthrough infection was provided by COVID-19 vaccine boosters, or third doses, according to Saxena, an assistant professor in the department of medicine at NYU Langone Health. Even among SLE patients who were well immunised, SARS-CoV-2 infection cases were often moderate.

According to the co-senior investigator and rheumatologist Peter Izmirly, MD, "Our research also demonstrates that most SLE patients who are properly immunised and boosted mounted good responses despite being on immune suppression." Izmirly teaches as an associate professor in the NYU Langone Health Department of Medicine.

To find out if there is an antibody "cutoff" level below which SLE patients are more susceptible to SARS-CoV-2 infection, researchers advise additional surveillance of patients.

The hospitalisation rates for SLE patients at NYU Langone during the first wave of the pandemic in spring 2020 were more than twice as high as those for those without the illness, the researchers find, even though mortality rates were the same.