Covid omicron booster offers some protection against XBB variants

Pfizer‘sand modernA Centers for Disease Control and Prevention study released Wednesday found that Omicron boosters reduced the risk of mild illness from the XBB family of subvariants compared to people who weren’t vaccinated.

The CDC study provides the first estimate of the real-world efficacy of Omicron Shot against the XBB family of subvariants. Some scientists warn that the XBB variant is so good at evading antibodies that block infection that it could trigger another Covid wave.

For people aged 18 to 49, the Omicron booster reduced the risk of mild illness due to the XBB subtype by approximately 48% 2-3 months after vaccination. According to the study, vaccination provided protection against minor illnesses by 38% for people aged 50 to 64 and 42% for people aged 65 and over.

CDC officials said at a press conference Wednesday that the study’s findings were reassuring because people who received boosters received more protection than those who didn’t. Protection against serious illness should be higher, they said, although not possible.

For the 18- to 49-year-old group, it “reduces the risk of symptomatic infections by about half at the population level,” said Ruth Link-Gelles, PhD, a CDC employee and author of the study.

“What we know from past experience is that vaccines generally provide better protection against more serious diseases,” said Link-Gelles. “Thus, these are estimates for symptomatic infections, and similar estimates for hospitalizations and deaths would be expected to be higher.”

The XBB.1.5 subvariant has rapidly become prevalent in the United States and now accounts for approximately 49% of new Covid cases nationwide. World Health Organization officials describe XBB.1.5 as the most contagious version of the virus to date, but mutations that suggest it makes people sicker than other variants is not.

Scientists have discovered that XBB.1.5 is highly immune evasive and has mutations that allow it to bind better to human cells. It has been shown to offer just as much protection to the family as it does to BA.5 and its descendants BQ.1 and BQ.1.1.

For example, adults aged 18-49 who received the Omicron booster had a 52% reduced risk of mild illness from BA.5 and their offspring, but a 48% reduced risk from the XBB family.

Dr. Brendan Jackson, Covid-19 Response Director for the CDC, said:

The study compared people who received the new boosters with people who received two to four doses of the original vaccine. The booster targets Omicron BA.5 and the original strain of his Covid that originated in Wuhan, China, while the older shot only targets the original virus strain.

People who only had their first injection usually had their last injection about 13 months ago. According to Link-Gelles, the weakened immunity observed with older vaccines provided little protection against mild illness. She said it’s too early to draw any conclusions about how protection from Omicron boosters will last.

“Protection against symptomatic infections may decline over time, but protection against more serious illnesses may persist over time,” Link-Gelles said. increase.

The CDC study looked at Covid test results from about 29,000 people between December and January 13th. During that period, XBB.1.5 rose from 2.4% to approximately 37% of cases. Of her >13,000 individuals who tested positive, 78% detected the BA.5-associated subvariant and 22% detected her XBB-associated subvariant.

In this study, detailed genomic analysis was not performed on all positive-testing samples to determine with 100% certainty which subvariant caused infection. Instead, scientists used quarks in PCR tests to determine which variant likely caused the infection.

The BA.5-related subvariant has a mutation that deletes the tested viral spike gene, whereas the XBB subvariant lacks this deletion. If the gene is detected, it is likely XBB, if not, it is likely BA.5-associated.