Covid-19 cases are once again rising across the United States. According to the US Centers for Disease Control and Prevention (CDC), as of July 8, 2025, a total of 25 US states, including Florida and Texas, are seeing a spike in infections, marking the return of a “summer wave.”
Experts say the rise is due to a mix of fading immunity, new Covid-19 variants, and summer behaviour patterns such as travel, crowded gatherings, and people spending more time indoors with air-conditioning.
New Covid-19 variants behind the surge
The CDC and other health bodies say that the new summer wave is being driven by two fast-spreading sub-variants: NB.1.8.1 (also called Nimbus) and XFG (also known as Stratus).
NB.1.8.1 or “Nimbus” Variant
- Part of the Omicron family.
- Known to cause mild to moderate respiratory symptoms.
- Most notable for its extremely painful sore throat, often described as feeling like “razor blades.”
- As of early June, 37 per cent of all US cases were linked to this variant.
- It does not cause severe illness, but it spreads very easily.
XFG or “Stratus” Variant
- Also, a descendant of the Omicron strain.
- Now spreading rapidly worldwide.
- Listed as a ‘Variant Under Monitoring’ by the World Health Organization (WHO).
- Symptoms may include hoarseness or a raspy voice, along with the usual Covid-19 signs like fatigue, cough, congestion, and fever.
- Experts say XFG could become the next dominant global variant.
Common Covid-19 symptoms to watch out for
Both NB.1.8.1 and XFG typically cause Omicron-like symptoms, including:
- Sore throat
- Runny nose
- Fever
- Cough
- Fatigue
- Muscle aches
- Loss of taste or smell
- Appetite loss
Less common symptoms include diarrhoea and nausea.
Other Covid-19 variants in circulation
JN.1 Variant (Seen in India)
- Caused a small spike in India earlier this year
- Symptoms include sore throat, body ache, and fatigue
- Mild in most people, but can be risky for older adults and those with health issues
LP.8.1 Variant (US and Europe)
- Now the dominant variant in parts of the US and Europe
- It spreads quickly, including among vaccinated people
- Not more severe, but it is better at avoiding immunity, making it harder to control
Experts say it’s important to stay informed, continue practising basic hygiene, and consider booster shots, especially for those at higher risk. While most cases remain mild, Covid-19 is still evolving, and hence we should stay aware.
