Yes. The updated 2024-2025 COVID-19 vaccines provide meaningful protection against the newest circulating variants, including XEC, which became the dominant strain globally in late 2024. While no vaccine is a perfect match for every new variant, lab studies confirm the current shots boost your immune response against XEC and other recent strains.
What the New Variant Actually Is
XEC is a recombinant variant, meaning it formed when two existing strains (KS.1.1 and KP.3.3, both descendants of JN.1) swapped genetic material inside a co-infected person. The earliest sample was collected in June 2024, and by late November it accounted for about 37% of globally sequenced cases, overtaking the previously dominant KP.3.1.1. XEC spreads roughly 13% more efficiently than KP.3.1.1, which is why it gained ground so quickly.
The good news: there are no reports of XEC causing more severe illness than other circulating variants. Its edge comes from modest improvements in immune evasion, not from making people sicker.
How Well the Current Vaccines Work Against XEC
The mRNA vaccines from Pfizer and Moderna for the 2024-2025 season target a strain called KP.2. The protein-based Novavax vaccine targets JN.1. Neither is a direct match for XEC, but both are close relatives on the same branch of the viral family tree, and the cross-protection is real.
A study published in The Lancet Infectious Diseases measured neutralizing antibody levels one month after vaccination with the KP.2-adapted shot. Antibody levels against XEC were about 2.3-fold lower than against the ancestral JN.1 strain, but still robust. For context, the vaccine generated strong responses across all tested variants: JN.1, KP.3, KP.2.3, KP.3.1.1, and XEC. The WHO’s assessment is that current vaccines “are expected to remain cross-reactive to this variant against symptomatic and severe disease.” In practical terms, you’re building a wall that’s slightly shorter against XEC than against the strain the vaccine was designed for, but still tall enough to matter, especially for preventing hospitalization.
Your Vaccine Options
Three types of COVID-19 vaccine are available in the United States for the 2024-2025 season:
- Pfizer (Comirnaty) and Moderna (Spikevax) are mRNA vaccines targeting the KP.2 strain. These are the most widely available options.
- Novavax (Nuvaxovid) is a protein-based vaccine targeting JN.1, authorized for ages 12 and older. This is a good alternative if you prefer a non-mRNA option. It uses a more traditional approach: a lab-made version of the spike protein paired with an immune-boosting ingredient.
All three generate cross-reactive immunity against XEC and other currently circulating strains.
Who Should Get a Shot and When
The CDC’s Advisory Committee on Immunization Practices recommends the 2024-2025 vaccine for everyone aged 6 months and older. For most people, that means a single updated dose. If you’ve never received any COVID vaccine, Novavax requires a two-dose series given three weeks apart, while the mRNA vaccines have their own initial series schedules.
Two groups are advised to get a second dose of the updated vaccine, given six months after the first (with a minimum interval of two months):
- Adults 65 and older
- People aged 6 months to 64 with moderate or severe immune compromise (such as organ transplant recipients or those on immunosuppressive therapy)
People with significant immune compromise can also discuss getting a third or additional dose with their healthcare provider, since their immune systems may not mount as strong a response from the standard schedule.
If You Recently Had COVID
You don’t need to rush to get vaccinated right after an infection. The CDC says you can delay your vaccine for three months after symptoms started, or three months after a positive test if you had no symptoms. A recent infection gives your immune system a temporary boost, so waiting allows you to get the most benefit from the shot when that natural protection starts to fade.
Why the Vaccine Doesn’t Perfectly Match Each Variant
COVID-19 vaccines are updated roughly once a year, similar to the flu shot. Manufacturers finalize their target strain months before the vaccine ships, and the virus keeps evolving in the meantime. The FDA initially told companies to target JN.1 in early June 2024, then switched to KP.2 later that month as newer data came in. By the time people were rolling up their sleeves in the fall, XEC had emerged. This lag is built into the process and is the same tradeoff we’ve accepted with flu vaccines for decades.
The reason it still works: variants don’t change so dramatically from one generation to the next that the immune system can’t recognize them. XEC descends from JN.1, and the KP.2 and JN.1 vaccine targets are close enough relatives that your antibodies and immune memory cells can still latch on. Protection against infection may be partial, but protection against severe illness, hospitalization, and death holds up much better because that relies on deeper layers of immune memory that are harder for small mutations to evade.