Immune system continues to remember the 'coronavirus'

A year after infection with the coronavirus, when antibodies in the blood are barely detectable, the immune system continues to “remember” the virus and should respond to some extent upon re-encountering it, a study from China suggests.

Researchers studied 141 people infected with the virus in the first half of 2020 who provided blood samples 12 months later. None of them had been vaccinated in the interim. Most individuals still had low levels of antibodies, and most of those younger than 60 still had some antibodies that could neutralize the virus, according to a report published on Wednesday in The Lancet Microbe.

But in everyone – regardless of age or severity of the original infection, and including patients who had lost their neutralizing antibodies – responses by so-called memory B cells and memory T cells were still evident “and were not disrupted by new variants,” the researchers said. These defenses do not prevent infection but they do help to prevent severe disease.

“Current SARS-CoV-2 vaccines are mainly focused on neutralizing antibodies,” the researchers noted. “These data underline the importance of broad B-cell and T-cell immunity for future vaccine strategies targeting SARS-CoV-2.”

COVID while pregnant more common, less severe with Omicron

Women who were pregnant during the recent Omicron surge had more than eight times the rate of COVID-19 diagnoses, but lower odds of severe illness compared with pregnant women diagnosed earlier in the pandemic, according to new research.

Doctors in Texas studied 2,641 women with COVID-19 infections during pregnancy from May 2020 through January 2022. While the weekly numbers of deliveries were similar throughout the study period, the average weekly number of infected women giving birth was 17 early in the pandemic, 14 during the Delta era, and 138 during Omicron, the researchers reported on Thursday in JAMA.

Fewer than 1% of women infected during the Omicron wave required hospitalization, compared to nearly 12% during Delta, they found. “We got very lucky” that Omicron’s transmissibility was not matched by its severity, study leader Dr. Emily Adhikari of UT Southwestern said in a statement.