The vaccine advisers recommend the switch to the JN.1 strain

Precise News

The World Health Organization (WHO) Technical Advisory Group on COVID-19 Vaccine Composition, which meets about every 6 months to assess if any changes are needed, has recommended that the next COVID vaccine formulations use a monovalent (single-strain) JN.1 lineage.
The group met in the middle of April to review the genetic and antigenic evolution of SARS-CoV-2, with an eye toward vaccine composition implications.
In a statement, the experts note that the XBB lineage has been displaced by JN.1 and said that, over the short-term, circulating variants will likely be derived from JN.1.
A year ago, the group recommended a switch to XBB.1.5 for COVID vaccines, but evidence from animal studies and human sera experiments suggests that XBB.1.5 and JN.1 are antigenically distinct.
Current vaccine might be less effective as JN.1 evolves “There are further reductions in cross neutralization of JN.1 variants with F456L and/or R346T substitutions,” the advisory group said.
Meanwhile, a single immunogenicity study in humans of a candidate monovalent JN.1 vaccine suggests that it produces higher neutralization antibodies against co-circulating JN.1 variants such as KP.2 than does the XBB.1.5 vaccine.
They urged countries to continue to use any COVID vaccines that are emergency listed or prequalified by the WHO and emphasized that COVID vaccination shouldn’t be delayed while waiting for updated versions.
FDA to consider strain recommendations in mid May The US Food and Drug Administration (FDA) Vaccines and Related Biological Products Advisory Committee (VRBPAC) will meet on May 16 to discuss and make strain-selection recommendations for 2024-25 COVID vaccines.


The next COVID vaccine formulations should employ a monovalent (single-strain) JN, according to the recommendation of the World Health Organization’s (WHO) Technical Advisory Group on COVID-19 Vaccine Composition, which convenes approximately every six months to evaluate whether any modifications are required. just one ancestor.

In order to discuss the potential implications for vaccine composition, the group convened in mid-April to examine the genetic and antigenic evolution of SARS-CoV-2.

The experts observe in a statement that JN has replaced the XBB lineage. 1 and stated that circulating variants will probably come from JN in the near future. 1.

The group suggested a move to XBB a year ago. 1.5 for COVID vaccines, however data from experiments on human sera and animals indicates that XBB. JN and 1.5. 1 differ in terms of antigens. investigations on animals and blood tests on humans after XBB exposure. 1.5 indicates that neutralization titers against JN are present after vaccination or infection. 1are two to five times less abundant than XBB titers. Immunization antigen 1.5.

The JN vaccine may be more effective than the current one. One changes.

“JN’s cross-neutralization has decreased even more. 1 versions that have F456L and/or R346T substitutions, according to the advisory panel. The two substitutions, which are known as FLiRT (F for L at position 456 and R for T at position 346), have been observed by virologists to appear in previous iterations of SARS-CoV-2.

For instance, in the US, a JN. one KP-named spinoff. The JN was surpassed by 2 that has the FLiRT replacements. According to the Centers for Disease Control and Prevention (CDC), the most frequently detected variant is 1 parent virus, according to their most recent estimates of variant proportion.

Few studies have estimated the relative vaccine effectiveness (VE) for the XBB, according to the experts at WHO. Vaccine at point five during JN. According to one circulation, there is a small decrease in VE against JN but some protection during the first three months following vaccination. 1 for defense against serious and symptomatic illness, in line with the findings of neutralization antibody titer studies. Nonetheless, they mentioned that XBB’s capability. The 1.5 vaccination may not be as effective in preventing symptoms as it once was because SARS-CoV-2 is still evolving from JN. 1.

A solitary human immunogenicity study of a potential monovalent JN is underway. According to one vaccination, it generates more neutralizing antibodies against JN that is also co-circulating. variations, like KP, in 1. 2. compared to the XBB. 1:5 vaccination.

A number of limitations were noted by the advisors regarding their analysis, such as incomplete genetic surveillance, a small number of viruses that were sequenced, and the challenge of forecasting the potential effects of mutations seen in the more recent JN on public health. 1 variations.

They stressed that COVID vaccination shouldn’t be postponed while waiting for updated versions and asked nations to keep using any COVID vaccines that the WHO has prequalified or emergency listed.

FDA to take strain recommendations into account by mid-May.

The US FDA Vaccines and Related Biological Products Advisory Committee (VRBPAC) will convene on May 16 to deliberate and recommend strain selection for the COVID-19 vaccine in the years 2024–25.

The organization stated that it will provide the background information its members will need for the discussions on its website at least two days prior to the meeting, and that the meeting will be accessible online.

scroll to top