The CDC advisory panel approves the new Merck RSV for infants

A group of Centers for Disease Control and Prevention (CDC) voted 5-2 advisers to recommend a new blow that can prevent the serious disease and the death of the syncytial respiratory virus (RSV) in infants yesterday.

Merck’s drugs, called enlosie (Clesrovimab) is the second product to protect babies from RSV, a virus which causes between 58,000 and 80,000 hospitalizations and hundreds of deaths in children under the age of 5 in the United States each year.

What is Clesrovimab?

Clesrovimab is a monoclonal antibody which is given as a shot to babies 8 months or less that were born during or entering their first RSV season. The RSV season generally extends from October to March.

It works as a vaccine because it helps protect the baby from the disease. Vaccines introduce parts or copies of a virus to the body, causing the immune system to recognize and destroy this virus in the future. Clesrovimab, on the other hand, delivers protective antibodies directly with the baby so that it is protected immediately.

Antibodies are sufficient to reduce the risk of serious illness for the first season of a baby’s RSV, when their respiratory tract still develops and most sensitive to infection, said Cody Meissner, MD, panellist and pediatric teacher at the Dartmouth Geisel School of Medicine. By the second or third season of a child’s RSV, their body is often enough to fight infection and develop an immunity that will protect them in the future.

How is it administered?

Health care providers give Keyerovimab like a photo in the muscle outside the baby’s thigh. All infants receive the same dose of Clesrovimab, regardless of their weight.

The Clesrovimab should be given in the first week of the life of an infant for the best protection, said Adam Macneil, PHD, MBA, deputy branch chief for epidemiology, branch of respiratory viruses at the CDC.

Macneil added that it is preferable to give the vaccine to the hospital where the baby is born because 45% of newborns do not have commercial health insurance and do not see a supplier of primary care during the first week of life.

The panel voted unanimously to include Clesrovimab in the Vaccines for Children (VFC) program. VFC provides free vaccines to children who are not insured and under-assured and who may not be able to access vaccination otherwise.

The votes of June 25 were the first to a new panel of eight members of the Committee that the Secretary of Health Robert F. Kennedy Jr. sorted on the aspect after having rejected the previous panelists.

How does he compare himself to other RSV preventive drugs?

The FDA approved the first RSV prevention drug for babies, called Nisrevimab in July 2023. Children up to 24 months can receive Nisrevimab for their first two seasons of Vrs.

Clesrovimab is currently approved for babies up to 8 months.

“Having several products available with different liaison sites will be beneficial in the event that resistant mutations emerge to one or the other product. If one product is disturbing the offer, as experienced during the 2023-24 season, the availability of the other product can help prevent shortages,” said Macneil.

A CDC working group which analyzed and prepared the presentation data at the meeting this week concluded that the two drugs work well and that there is no preference for one compared to the other. They also said he was sure to “mix and match”, giving Clesrovimab for the first RSV season and Nisrevimab for the second.

The speakers also have the possibility of being vaccinated against the RSV to pass antibodies to the fetus so that the baby was born against the virus. The only maternal vaccine available is Abrysvo de Pfizer.

Macneil said some babies born from vaccinated mothers may need additional RSV protection. These include babies born from mothers with an unknown vaccination status, those who were born less than 14 days after maternal vaccination, and those born from mothers suffering from a medical condition which makes the passage of antibody through the placenta difficult.

What do we know about efficiency and security?

A clinical phase 2B / 3 clinical trial of the CLESROVIMAB has shown that the drug prevented a serious RSV disease, although 150 days after vaccination.

The data presented by the CDC indicated that there was no increased risk of fever or serious reactions in the group which received keys compared to a placebo. The biggest adverse events were the people who obtained the RSV despite their vaccination and had complications linked to this infection.

Macneil has shared data showing that Nisrevimab has so far been very effective in protecting young children. In the past two RSV seasons, Norsevimab has been between 63% and 72% efficient to prevent emergency visits and 80% to 90% to keep babies away from the intensive care unit (USI).

The hospitalization rates associated with the RSV have reduced by almost half in infants from 0 to 2 months after the deployment of new vaccines. The CDC also recorded a reduction of 31% to 38% in the hospitalization of infants under 7 months.